One of the principal new features of Csound 6 is the support of arrays. This chapter aims to demonstrate how to use arrays using the methods currently implemented.
The outline of this chapter is as follows:
One-dimensional arrays - also called vectors - are the most commonly used type of array, but in Csound6 you can also use arrays with two or more dimensions. The way in which the number of dimensions is designated is very similar to how it is done in other programming languages.
The code below denotes the second element of a one-dimensional array (as usual, indexing an element starts at zero, so kArr[0] would be the first element):
kArr[1]
The following denotes the second column in the third row of a two-dimensional array:
kArr[2][1]
Note that the square brackets are not used everywhere. This is explained in more detail below under 'Naming Conventions'.
Like most other variables in Csound, arrays can be either i-rate or k-rate. An i-array can only be modified at init-time, and any operation on it is only performed once, at init-time. A k-array can be modified during the performance, and any (k-) operation on it will be performed in every k-cycle (!). Here is a very simple example:
EXAMPLE 03E01_i_k_arrays.csd
<CsoundSynthesizer> <CsOptions> -nm128 ;no sound and reduced messages </CsOptions> <CsInstruments> sr = 44100 ksmps = 4410 ;10 k-cycles per second instr 1 iArr[] array 1, 2, 3 iArr[0] = iArr[0] + 10 prints " iArr[0] = %d\n\n", iArr[0] endin instr 2 kArr[] array 1, 2, 3 kArr[0] = kArr[0] + 10 printks " kArr[0] = %d\n", 0, kArr[0] endin </CsInstruments> <CsScore> i 1 0 1 i 2 1 1 </CsScore> </CsoundSynthesizer> ;example by joachim heintz
The output shows this:
iArr[0] = 11
kArr[0] = 11
kArr[0] = 21
kArr[0] = 31
kArr[0] = 41
kArr[0] = 51
kArr[0] = 61
kArr[0] = 71
kArr[0] = 81
kArr[0] = 91
kArr[0] = 101
Although both instruments run for one second, the operation to increment the first array value by ten is executed only once in the i-rate version of the array. But in the k-rate version, the incrementation is repeated in each k-cycle - in this case every 1/10 second, but usually something around every 1/1000 second. A good opportunity to throw off rendering power for useless repetitions, or to produce errors if you intentionally wanted to operate something only once ...
Like any other variable in Csound, an array usually has a local scope - this means that it is only recognized within the scope of the instrument in which it has been defined. If you want to use arrays in a globally (across instruments), then you have to prefix the variable name with the character g, (as is done with other types of global variable in Csound). The next example demonstrates local and global arrays at both i- and k-rate.
EXAMPLE 03E02_Local_vs_global_arrays.csd
<CsoundSynthesizer>
<CsOptions>
-nm128 ;no sound and reduced messages
</CsOptions>
<CsInstruments>
ksmps = 32
instr i_local
iArr[] array 1, 2, 3
prints " iArr[0] = %d iArr[1] = %d iArr[2] = %d\n",
iArr[0], iArr[1], iArr[2]
endin
instr i_local_diff ;same name, different content
iArr[] array 4, 5, 6
prints " iArr[0] = %d iArr[1] = %d iArr[2] = %d\n",
iArr[0], iArr[1], iArr[2]
endin
instr i_global
giArr[] array 11, 12, 13
endin
instr i_global_read ;understands giArr though not defined here
prints " giArr[0] = %d giArr[1] = %d giArr[2] = %d\n",
giArr[0], giArr[1], giArr[2]
endin
instr k_local
kArr[] array -1, -2, -3
printks " kArr[0] = %d kArr[1] = %d kArr[2] = %d\n",
0, kArr[0], kArr[1], kArr[2]
turnoff
endin
instr k_local_diff
kArr[] array -4, -5, -6
printks " kArr[0] = %d kArr[1] = %d kArr[2] = %d\n",
0, kArr[0], kArr[1], kArr[2]
turnoff
endin
instr k_global
gkArr[] array -11, -12, -13
turnoff
endin
instr k_global_read
printks " gkArr[0] = %d gkArr[1] = %d gkArr[2] = %d\n",
0, gkArr[0], gkArr[1], gkArr[2]
turnoff
endin
</CsInstruments>
<CsScore>
i "i_local" 0 0
i "i_local_diff" 0 0
i "i_global" 0 0
i "i_global_read" 0 0
i "k_local" 0 1
i "k_local_diff" 0 1
i "k_global" 0 1
i "k_global_read" 0 1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
So far we have discussed only arrays of numbers. It is also possible to have arrays of strings, which can be very useful in many situations, for instance while working with file paths.1 Here is a very simple example first, followed by a more extended one.
EXAMPLE 03E03_String_arrays.csd
<CsoundSynthesizer>
<CsOptions>
-nm128 ;no sound and reduced messages
</CsOptions>
<CsInstruments>
ksmps = 32
instr 1
String = "onetwothree"
S_Arr[] init 3
S_Arr[0] strsub String, 0, 3
S_Arr[1] strsub String, 3, 6
S_Arr[2] strsub String, 6
printf_i "S_Arr[0] = '%s'\nS_Arr[1] = '%s'\nS_Arr[2] = '%s'\n", 1,
S_Arr[0], S_Arr[1], S_Arr[2]
endin
</CsInstruments>
<CsScore>
i 1 0 1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
EXAMPLE 03E04_Anagram.csd
<CsoundSynthesizer>
<CsOptions>
-dnm0
</CsOptions>
<CsInstruments>
ksmps = 32
giArrLen = 5
gSArr[] init giArrLen
opcode StrAgrm, S, Sj
;changes the elements in Sin randomly, like in an anagram
Sin, iLen xin
if iLen == -1 then
iLen strlen Sin
endif
Sout = ""
;for all elements in Sin
iCnt = 0
iRange = iLen
loop:
;get one randomly
iRnd rnd31 iRange-.0001, 0
iRnd = int(abs(iRnd))
Sel strsub Sin, iRnd, iRnd+1
Sout strcat Sout, Sel
;take it out from Sin
Ssub1 strsub Sin, 0, iRnd
Ssub2 strsub Sin, iRnd+1
Sin strcat Ssub1, Ssub2
;adapt range (new length)
iRange = iRange-1
loop_lt iCnt, 1, iLen, loop
xout Sout
endop
instr 1
prints "Filling gSArr[] in instr %d at init-time!\n", p1
iCounter = 0
until (iCounter == giArrLen) do
S_new StrAgrm "csound"
gSArr[iCounter] = S_new
iCounter += 1
od
endin
instr 2
prints "Printing gSArr[] in instr %d at init-time:\n [", p1
iCounter = 0
until (iCounter == giArrLen) do
printf_i "%s ", iCounter+1, gSArr[iCounter]
iCounter += 1
od
prints "]\n"
endin
instr 3
printks "Printing gSArr[] in instr %d at perf-time:\n [", 0, p1
kcounter = 0
until (kcounter == giArrLen) do
printf "%s ", kcounter+1, gSArr[kcounter]
kcounter += 1
od
printks "]\n", 0
turnoff
endin
instr 4
prints "Modifying gSArr[] in instr %d at init-time!\n", p1
iCounter = 0
until (iCounter == giArrLen) do
S_new StrAgrm "csound"
gSArr[iCounter] = S_new
iCounter += 1
od
endin
instr 5
prints "Printing gSArr[] in instr %d at init-time:\n [", p1
iCounter = 0
until (iCounter == giArrLen) do
printf_i "%s ", iCounter+1, gSArr[iCounter]
iCounter += 1
od
prints "]\n"
endin
instr 6
kCycle timeinstk
printks "Modifying gSArr[] in instr %d at k-cycle %d!\n", 0,
p1, kCycle
kCounter = 0
until (kCounter == giArrLen) do
kChar random 33, 127
S_new sprintfk "%c ", int(kChar)
gSArr[kCounter] strcpyk S_new ;'=' should work but does not
kCounter += 1
od
if kCycle == 3 then
turnoff
endif
endin
instr 7
kCycle timeinstk
printks "Printing gSArr[] in instr %d at k-cycle %d:\n [",
0, p1, kCycle
kCounter = 0
until (kCounter == giArrLen) do
printf "%s ", kCounter+1, gSArr[kCounter]
kCounter += 1
od
printks "]\n", 0
if kCycle == 3 then
turnoff
endif
endin
</CsInstruments>
<CsScore>
i 1 0 1
i 2 0 1
i 3 0 1
i 4 1 1
i 5 1 1
i 6 1 1
i 7 1 1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
Prints:
Filling gSArr[] in instr 1 at init-time!
Printing gSArr[] in instr 2 at init-time:
[nudosc coudns dsocun ocsund osncdu ]
Printing gSArr[] in instr 3 at perf-time:
[nudosc coudns dsocun ocsund osncdu ]
Modifying gSArr[] in instr 4 at init-time!
Printing gSArr[] in instr 5 at init-time:
[ousndc uocdns sudocn usnocd ouncds ]
Modifying gSArr[] in instr 6 at k-cycle 1!
Printing gSArr[] in instr 7 at k-cycle 1:
[s < x + ! ]
Modifying gSArr[] in instr 6 at k-cycle 2!
Printing gSArr[] in instr 7 at k-cycle 2:
[P Z r u U ]
Modifying gSArr[] in instr 6 at k-cycle 3!
Printing gSArr[] in instr 7 at k-cycle 3:
[b K c " h ]
Collecting audio signals in an array simplifies working with multiple channels, as one of many possible cases of use. Here are two simple examples, one for local audio arrays and the other for global audio arrays.
EXAMPLE 03E05_Local_audio_array.csd
<CsoundSynthesizer>
<CsOptions>
-odac -d
</CsOptions>
<CsInstruments>
sr = 44100
ksmps = 32
nchnls = 2
0dbfs = 1
instr 1
aArr[] init 2
a1 oscils .2, 400, 0
a2 oscils .2, 500, 0
kEnv transeg 1, p3, -3, 0
aArr[0] = a1 * kEnv
aArr[1] = a2 * kEnv
outch 1, aArr[0], 2, aArr[1]
endin
instr 2 ;to test identical names
aArr[] init 2
a1 oscils .2, 600, 0
a2 oscils .2, 700, 0
kEnv transeg 0, p3-p3/10, 3, 1, p3/10, -6, 0
aArr[0] = a1 * kEnv
aArr[1] = a2 * kEnv
outch 1, aArr[0], 2, aArr[1]
endin
</CsInstruments>
<CsScore>
i 1 0 3
i 2 0 3
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
EXAMPLE 03E06_Global_audio_array.csd
<CsoundSynthesizer>
<CsOptions>
-odac -d
</CsOptions>
<CsInstruments>
sr = 44100
ksmps = 32
nchnls = 2
0dbfs = 1
gaArr[] init 2
instr 1 ; left channel
kEnv loopseg 0.5, 0, 0, 1,0.003, 1,0.0001, 0,0.9969
aSig pinkish kEnv
gaArr[0] = aSig
endin
instr 2 ; right channel
kEnv loopseg 0.5, 0, 0.5, 1,0.003, 1,0.0001, 0,0.9969
aSig pinkish kEnv
gaArr[1] = aSig
endin
instr 3 ; reverb
aInSigL = gaArr[0] / 3
aInSigR = gaArr[1] / 2
aRvbL,aRvbR reverbsc aInSigL, aInSigR, 0.88, 8000
gaArr[0] = gaArr[0] + aRvbL
gaArr[1] = gaArr[1] + aRvbR
outs gaArr[0]/4, gaArr[1]/4
gaArr[0] = 0
gaArr[1] = 0
endin
</CsInstruments>
<CsScore>
i 1 0 10
i 2 0 10
i 3 0 12
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz, using code by iain mccurdy
If you use soundin/diskin, the array is created automatically in the size which fits to the number of channels in the input file:
arr[] diskin "7chnls.aiff", 1
will create an audio array of size 7 according to the seven channel input file.
An array must be created (via init or array / fillarray2) as kMyArrayName plus ending brackets. The brackets determine the dimensions of the array. So
kArr[] init 10
creates a one-dimensional array of length 10, whereas
kArr[][] init 10, 10
creates a two-dimensional array with 10 rows and 10 columns.
After the initialization of the array, referring to the array as a whole is done without any brackets. Brackets are only used if an element is indexed:
kArr[] init 10 ;with brackets because of initialization kLen = lenarray(kArr) ;without brackets kFirstEl = kArr[0] ;with brackets because of indexing
The same syntax is used for a simple copy via the '=' operator:
kArr1[] array 1, 2, 3, 4, 5 ;creates kArr1 kArr2[] = kArr1 ;creates kArr2 as copy of kArr1
An array can currently be created by four methods: with the init opcode, with array/fillarray, with genarray, or as a copy of an already existing array with the '=' operator.
The most general method, which works for arrays of any number of dimensions, is to use the init opcode. Here you define a specified space for the array:
kArr[] init 10 ;creates a one-dimensional array with length 10 kArr[][] init 10, 10 ;creates a two-dimensional array
If you want to fill an array with distinct values, you can use the fillarray opcode. This line creates a vector with length 4 and puts in the numbers [1, 2, 3, 4]:
kArr[] fillarray 1, 2, 3, 4
You can also use this opcode for filling two-dimensional arrays:3
EXAMPLE 03E07_Fill_multidim_array.csd
<CsoundSynthesizer> <CsOptions> -nm0 </CsOptions> <CsInstruments> ksmps = 32 instr 1 iArr[][] init 2,3 iArr array 1,2,3,7,6,5 iRow = 0 until iRow == 2 do iColumn = 0 until iColumn == 3 do prints "iArr[%d][%d] = %d\n", iRow, iColumn, iArr[iRow][iColumn] iColumn += 1 enduntil iRow += 1 od endin </CsInstruments> <CsScore> i 1 0 0 </CsScore> </CsoundSynthesizer> ;example by joachim heintz
This opcode creates an array which is filled by a series of numbers from a starting value to an (included) ending value. Here are some examples:
iArr[] genarray 1, 5 ; creates i-array with [1, 2, 3, 4, 5] kArr[] genarray_i 1, 5 ; creates k-array at init-time with [1, 2, 3, 4, 5] iArr[] genarray -1, 1, 0.5 ; i-array with [-1, -0.5, 0, 0.5, 1] iArr[] genarray 1, -1, -0.5 ; [1, 0.5, 0, -0.5, -1] iArr[] genarray -1, 1, 0.6 ; [-1, -0.4, 0.2, 0.8]
The opcode lenarray reports the length of an i- or k-array. As with many opcodes now in Csound 6, it can be used either in the traditional way (Left-hand-side <- Opcode <- Right-hand-side), or as a function. The next example shows both usages, for i- and k-arrays. For multidimensional arrays, lenarray returns the length of the first dimension (instr 5).
EXAMPLE 03E08_lenarray.csd
<CsoundSynthesizer>
<CsOptions>
-nm0
</CsOptions>
<CsInstruments>
ksmps = 32
instr 1 ;simple i-rate example
iArr[] fillarray 1, 3, 5, 7, 9
iLen lenarray iArr
prints "Length of iArr = %d\n", iLen
endin
instr 2 ;simple k-rate example
kArr[] fillarray 2, 4, 6, 8
kLen lenarray kArr
printks "Length of kArr = %d\n", 0, kLen
turnoff
endin
instr 3 ;i-rate with functional syntax
iArr[] genarray 1, 9, 2
iIndx = 0
until iIndx == lenarray(iArr) do
prints "iArr[%d] = %d\n", iIndx, iArr[iIndx]
iIndx += 1
od
endin
instr 4 ;k-rate with functional syntax
kArr[] genarray_i -2, -8, -2
kIndx = 0
until kIndx == lenarray(kArr) do
printf "kArr[%d] = %d\n", kIndx+1, kIndx, kArr[kIndx]
kIndx += 1
od
turnoff
endin
instr 5 ;multi-dimensional arrays
kArr[][] init 9, 5
kArrr[][][] init 7, 9, 5
printks "lenarray(kArr) (2-dim) = %d\n", 0, lenarray(kArr)
printks "lenarray(kArrr) (3-dim) = %d\n", 0, lenarray(kArrr)
endin
</CsInstruments>
<CsScore>
i 1 0 0
i 2 .1 .1
i 3 .2 0
i 4 .3 .1
i 5 .4 .1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
Prints:
Length of iArr = 5
Length of kArr = 4
iArr[0] = 1
iArr[1] = 3
iArr[2] = 5
iArr[3] = 7
iArr[4] = 9
kArr[0] = -2
kArr[1] = -4
kArr[2] = -6
kArr[3] = -8
lenarray(kArr) (2-dim) = 9
lenarray(kArrr) (3-dim) = 7
The opcode slicearray takes a slice of a (one-dimensional) array:
slicearray kArr, iStart, iEnd
returns a slice of kArr from index iStart to index iEnd (included).
The array for receiving the slice must have been created in advance:
kArr[] fillarray 1, 2, 3, 4, 5, 6, 7, 8, 9 kArr1[] init 5 kArr2[] init 4 kArr1 slicearray kArr, 0, 4 ;[1, 2, 3, 4, 5] kArr2 slicearray kArr, 5, 8 ;[6, 7, 8, 9]
EXAMPLE 03E09_slicearray.csd
<CsoundSynthesizer>
<CsOptions>
-n
</CsOptions>
<CsInstruments>
ksmps = 32
instr 1
;create and fill an array
kArr[] genarray_i 1, 9
;print the content
printf "%s", 1, "kArr = whole array\n"
kndx = 0
until kndx == lenarray(kArr) do
printf "kArr[%d] = %f\n", kndx+1, kndx, kArr[kndx]
kndx += 1
od
;build new arrays for the slices
kArr1[] init 5
kArr2[] init 4
;put in first five and last four elements
kArr1 slicearray kArr, 0, 4
kArr2 slicearray kArr, 5, 8
;print the content
printf "%s", 1, "\nkArr1 = slice from index 0 to index 4\n"
kndx = 0
until kndx == lenarray(kArr1) do
printf "kArr1[%d] = %f\n", kndx+1, kndx, kArr1[kndx]
kndx += 1
od
printf "%s", 1, "\nkArr2 = slice from index 5 to index 8\n"
kndx = 0
until kndx == lenarray(kArr2) do
printf "kArr2[%d] = %f\n", kndx+1, kndx, kArr2[kndx]
kndx += 1
od
turnoff
endin
</CsInstruments>
<CsScore>
i 1 0 1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
As function tables have been the classical way of working with arrays in Csound, switching between them and the new array facility in Csound is a basic operation. Copying data from a function table to a vector is done by copyf2array, whereas copya2ftab copies data from a vector to a function table:
copyf2array kArr, kfn ;from a function table to an array copya2ftab kArr, kfn ;from an array to a function table
The following presents a simple example of each operation.
EXAMPLE 03E10_copyf2array.csd
<CsoundSynthesizer>
<CsOptions>
-nm0
</CsOptions>
<CsInstruments>
ksmps = 32
;8 points sine wave function table
giSine ftgen 0, 0, 8, 10, 1
instr 1
;create array
kArr[] init 8
;copy table values in it
copyf2array kArr, giSine
;print values
kndx = 0
until kndx == lenarray(kArr) do
printf "kArr[%d] = %f\n", kndx+1, kndx, kArr[kndx]
kndx += 1
enduntil
;turn instrument off
turnoff
endin
</CsInstruments>
<CsScore>
i 1 0 0.1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
EXAMPLE 03E11_copya2ftab.csd
<CsoundSynthesizer>
<CsOptions>
-nm0
</CsOptions>
<CsInstruments>
ksmps = 32
;an 'empty' function table with 10 points
giTable ftgen 0, 0, -10, 2, 0
instr 1
;print inital values of giTable
puts "\nInitial table content:", 1
indx = 0
until indx == ftlen(giTable) do
iVal table indx, giTable
printf_i "Table index %d = %f\n", 1, indx, iVal
indx += 1
od
;create array with values 1..10
kArr[] genarray_i 1, 10
;print array values
printf "%s", 1, "\nArray content:\n"
kndx = 0
until kndx == lenarray(kArr) do
printf "kArr[%d] = %f\n", kndx+1, kndx, kArr[kndx]
kndx += 1
od
;copy array values to table
copya2ftab kArr, giTable
;print modified values of giTable
printf "%s", 1, "\nModified table content after copya2ftab:\n"
kndx = 0
until kndx == ftlen(giTable) do
kVal table kndx, giTable
printf "Table index %d = %f\n", kndx+1, kndx, kVal
kndx += 1
od
;turn instrument off
turnoff
endin
</CsInstruments>
<CsScore>
i 1 0 0.1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
You can copy the data of an f-signal - which contains the results of a Fast Fourier Transform - into an array with the opcode pvs2array. The counterpart pvsfromarray copies the content of an array to a f-signal.
kFrame pvs2array kArr, fSigIn ;from f-signal fSig to array kArr fSigOut pvsfromarray kArr [,ihopsize, iwinsize, iwintype]
Some care is needed to use these opcodes correctly:
Here is an example that implements a spectral high-pass filter. The f-signal is written to an array and the amplitudes of the first 40 bins are then zeroed.4 This is only done when a new frame writes its values to the array so as not to waste rendering power.
EXAMPLE 03E12_pvs_to_from_array.csd
<CsoundSynthesizer>
<CsOptions>
-o dac
</CsOptions>
<CsInstruments>
sr = 44100
ksmps = 32
nchnls = 2
0dbfs = 1
gifil ftgen 0, 0, 0, 1, "fox.wav", 0, 0, 1
instr 1
ifftsize = 2048 ;fft size set to pvstanal default
fsrc pvstanal 1, 1, 1, gifil ;create fsig stream from function table
kArr[] init ifftsize+2 ;create array for bin data
kflag pvs2array kArr, fsrc ;export data to array
;if kflag has reported a new write action ...
knewflag changed kflag
if knewflag == 1 then
; ... set amplitude of first 40 bins to zero:
kndx = 0 ;even array index = bin amplitude
kstep = 2 ;change only even indices
kmax = 80
loop:
kArr[kndx] = 0
loop_le kndx, kstep, kmax, loop
endif
fres pvsfromarray kArr ;read modified data back to fres
aout pvsynth fres ;and resynth
outs aout, aout
endin
</CsInstruments>
<CsScore>
i 1 0 2.7
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
Basically, with the opcodes pvs2array and pvsfromarray, you have complete access to every operation in the spectral domain. You could re-write the existing pvs transformations, you could change them, but you can also simply use the spectral data to do anything with it. The next example looks for the most prominent amplitudes in a frame, and then triggers another instrument.
EXAMPLE 03E13_fft_peaks_arpegg.csd
<CsoundSynthesizer>
<CsOptions>
-odac -d -m128
; Example by Tarmo Johannes
</CsOptions>
<CsInstruments>
sr = 44100
ksmps = 32
nchnls = 2
0dbfs = 1
giSine ftgen 0, 0, 4096, 10, 1
instr getPeaks
;generate signal to analyze
kfrcoef jspline 60, 0.1, 1 ; change the signal in time a bit for better testing
kharmcoef jspline 4, 0.1, 1
kmodcoef jspline 1, 0.1, 1
kenv linen 0.5, 0.05, p3, 0.05
asig foscil kenv, 300+kfrcoef, 1, 1+kmodcoef, 10, giSine
outs asig*0.05, asig*0.05 ; original sound in backround
;FFT analysis
ifftsize = 1024
ioverlap = ifftsize / 4
iwinsize = ifftsize
iwinshape = 1
fsig pvsanal asig, ifftsize, ioverlap, iwinsize, iwinshape
ithresh = 0.001 ; detect only peaks over this value
;FFT values to array
kFrames[] init iwinsize+2 ; declare array
kframe pvs2array kFrames, fsig ; even member = amp of one bin, odd = frequency
;detect peaks
kindex = 2 ; start checking from second bin
kcounter = 0
iMaxPeaks = 13 ; track up to iMaxPeaks peaks
ktrigger metro 1/2 ; check after every 2 seconds
if ktrigger == 1 then
loop:
; check with neigbouring amps - if higher or equal than previous amp
; and more than the coming one, must be peak.
if (kFrames[kindex-2]<=kFrames[kindex] &&
kFrames[kindex]>kFrames[kindex+2] &&
kFrames[kindex]>ithresh &&
kcounter<iMaxPeaks) then
kamp = kFrames[kindex]
kfreq = kFrames[kindex+1]
; play sounds with the amplitude and frequency of the peak as in arpeggio
event "i", "sound", kcounter*0.1, 1, kamp, kfreq
kcounter = kcounter+1
endif
loop_lt kindex, 2, ifftsize, loop
endif
endin
instr sound
iamp = p4
ifreq = p5
kenv adsr 0.1,0.1,0.5,p3/2
kndx line 5,p3,1
asig foscil iamp*kenv, ifreq,1,0.75,kndx,giSine
outs asig, asig
endin
</CsInstruments>
<CsScore>
i "getPeaks" 0 60
</CsScore>
</CsoundSynthesizer>
If the four basic math operators are used between an array and a scalar (number), the operation is applied to each element. The safest way to do this is to store the result in a new array:
kArr1[] fillarray 1, 2, 3 kArr2[] = kArr1 + 10 ;(kArr2 is now [11, 12, 13])
Here is an example of array-scalar operations.
EXAMPLE 03E14_array_scalar_math.csd
<CsoundSynthesizer>
<CsOptions>
-n -m128
</CsOptions>
<CsInstruments>
ksmps = 32
instr 1
;create array and fill with numbers 1..10
kArr1[] genarray_i 1, 10
;print content
printf "%s", 1, "\nInitial content:\n"
kndx = 0
until kndx == lenarray(kArr1) do
printf "kArr[%d] = %f\n", kndx+1, kndx, kArr1[kndx]
kndx += 1
od
;add 10
kArr2[] = kArr1 + 10
;print content
printf "%s", 1, "\nAfter adding 10:\n"
kndx = 0
until kndx == lenarray(kArr2) do
printf "kArr[%d] = %f\n", kndx+1, kndx, kArr2[kndx]
kndx += 1
od
;subtract 5
kArr3[] = kArr2 - 5
;print content
printf "%s", 1, "\nAfter subtracting 5:\n"
kndx = 0
until kndx == lenarray(kArr3) do
printf "kArr[%d] = %f\n", kndx+1, kndx, kArr3[kndx]
kndx += 1
od
;multiply by -1.5
kArr4[] = kArr3 * -1.5
;print content
printf "%s", 1, "\nAfter multiplying by -1.5:\n"
kndx = 0
until kndx == lenarray(kArr4) do
printf "kArr[%d] = %f\n", kndx+1, kndx, kArr4[kndx]
kndx += 1
od
;divide by -3/2
kArr5[] = kArr4 / -(3/2)
;print content
printf "%s", 1, "\nAfter dividing by -3/2:\n"
kndx = 0
until kndx == lenarray(kArr5) do
printf "kArr[%d] = %f\n", kndx+1, kndx, kArr5[kndx]
kndx += 1
od
;turnoff
turnoff
endin
</CsInstruments>
<CsScore>
i 1 0 .1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
Prints:
Initial content:
kArr[0] = 1.000000
kArr[1] = 2.000000
kArr[2] = 3.000000
kArr[3] = 4.000000
kArr[4] = 5.000000
kArr[5] = 6.000000
kArr[6] = 7.000000
kArr[7] = 8.000000
kArr[8] = 9.000000
kArr[9] = 10.000000
After adding 10:
kArr[0] = 11.000000
kArr[1] = 12.000000
kArr[2] = 13.000000
kArr[3] = 14.000000
kArr[4] = 15.000000
kArr[5] = 16.000000
kArr[6] = 17.000000
kArr[7] = 18.000000
kArr[8] = 19.000000
kArr[9] = 20.000000
After subtracting 5:
kArr[0] = 6.000000
kArr[1] = 7.000000
kArr[2] = 8.000000
kArr[3] = 9.000000
kArr[4] = 10.000000
kArr[5] = 11.000000
kArr[6] = 12.000000
kArr[7] = 13.000000
kArr[8] = 14.000000
kArr[9] = 15.000000
After multiplying by -1.5:
kArr[0] = -9.000000
kArr[1] = -10.500000
kArr[2] = -12.000000
kArr[3] = -13.500000
kArr[4] = -15.000000
kArr[5] = -16.500000
kArr[6] = -18.000000
kArr[7] = -19.500000
kArr[8] = -21.000000
kArr[9] = -22.500000
After dividing by -3/2:
kArr[0] = 6.000000
kArr[1] = 7.000000
kArr[2] = 8.000000
kArr[3] = 9.000000
kArr[4] = 10.000000
kArr[5] = 11.000000
kArr[6] = 12.000000
kArr[7] = 13.000000
kArr[8] = 14.000000
kArr[9] = 15.000000
If the four basic math operators are used between two arrays, their operation is applied element by element. The result can be easily stored in a new array:
kArr1[] fillarray 1, 2, 3 kArr2[] fillarray 10, 20, 30 kArr3[] = kArr1 + kArr2 ;(kArr3 is now [11, 22, 33])
Here is an example of array-array operations.
EXAMPLE 03E15_array_array_math.csd
<CsoundSynthesizer>
<CsOptions>
-n -m128
</CsOptions>
<CsInstruments>
ksmps = 32
instr 1
;create array and fill with numbers 1..10 resp .1..1
kArr1[] fillarray 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
kArr2[] fillarray 1, 2, 3, 5, 8, 13, 21, 34, 55, 89
;print contents
printf "%s", 1, "\nkArr1:\n"
kndx = 0
until kndx == lenarray(kArr1) do
printf "kArr1[%d] = %f\n", kndx+1, kndx, kArr1[kndx]
kndx += 1
od
printf "%s", 1, "\nkArr2:\n"
kndx = 0
until kndx == lenarray(kArr2) do
printf "kArr2[%d] = %f\n", kndx+1, kndx, kArr2[kndx]
kndx += 1
od
;add arrays
kArr3[] = kArr1 + kArr2
;print content
printf "%s", 1, "\nkArr1 + kArr2:\n"
kndx = 0
until kndx == lenarray(kArr3) do
printf "kArr3[%d] = %f\n", kndx+1, kndx, kArr3[kndx]
kndx += 1
od
;subtract arrays
kArr4[] = kArr1 - kArr2
;print content
printf "%s", 1, "\nkArr1 - kArr2:\n"
kndx = 0
until kndx == lenarray(kArr4) do
printf "kArr4[%d] = %f\n", kndx+1, kndx, kArr4[kndx]
kndx += 1
od
;multiply arrays
kArr5[] = kArr1 * kArr2
;print content
printf "%s", 1, "\nkArr1 * kArr2:\n"
kndx = 0
until kndx == lenarray(kArr5) do
printf "kArr5[%d] = %f\n", kndx+1, kndx, kArr5[kndx]
kndx += 1
od
;divide arrays
kArr6[] = kArr1 / kArr2
;print content
printf "%s", 1, "\nkArr1 / kArr2:\n"
kndx = 0
until kndx == lenarray(kArr6) do
printf "kArr5[%d] = %f\n", kndx+1, kndx, kArr6[kndx]
kndx += 1
od
;turnoff
turnoff
endin
</CsInstruments>
<CsScore>
i 1 0 .1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
minarray and maxarray return the smallest / largest value in an array, and optionally its index:
kMin [,kMinIndx] minarray kArr kMax [,kMaxIndx] maxarray kArr
Here is a simple example of these operations:
EXAMPLE 03E16_min_max_array.csd
<CsoundSynthesizer>
<CsOptions>
-nm0
</CsOptions>
<CsInstruments>
ksmps = 32
seed 0
instr 1
;create an array with 10 elements
kArr[] init 10
;fill in random numbers and print them out
kIndx = 0
until kIndx == 10 do
kNum random -100, 100
kArr[kIndx] = kNum
printf "kArr[%d] = %10f\n", kIndx+1, kIndx, kNum
kIndx += 1
od
;investigate minimum and maximum number and print them out
kMin, kMinIndx minarray kArr
kMax, kMaxIndx maxarray kArr
printf "Minimum of kArr = %f at index %d\n", kIndx+1, kMin, kMinIndx
printf "Maximum of kArr = %f at index %d\n\n", kIndx+1, kMax, kMaxIndx
turnoff
endin
</CsInstruments>
<CsScore>
i1 0 0.1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
This would create a different output each time you run it; for instance:
kArr[0] = -2.071383
kArr[1] = 97.150272
kArr[2] = 21.187835
kArr[3] = 72.199983
kArr[4] = -64.908241
kArr[5] = -7.276434
kArr[6] = -51.368650
kArr[7] = 41.324552
kArr[8] = -8.483235
kArr[9] = 77.560219
Minimum of kArr = -64.908241 at index 4
Maximum of kArr = 97.150272 at index 1
sumarray simply returns the sum of all values in an (numerical) array. Here is a simple example:
EXAMPLE 03E17_sumarray.csd
<CsoundSynthesizer>
<CsOptions>
-nm0
</CsOptions>
<CsInstruments>
ksmps = 32
seed 0
instr 1
;create an array with 10 elements
kArr[] init 10
;fill in random numbers and print them out
kIndx = 0
until kIndx == 10 do
kNum random 0, 10
kArr[kIndx] = kNum
printf "kArr[%d] = %10f\n", kIndx+1, kIndx, kNum
kIndx += 1
od
;calculate sum of all values and print it out
kSum sumarray kArr
printf "Sum of all values in kArr = %f\n", kIndx+1, kSum
turnoff
endin
</CsInstruments>
<CsScore>
i1 0 0.1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
Finally, scalearray scales the values of a given numerical array between a minimum and a maximum value. These lines ...
kArr[] fillarray 1, 3, 9, 5, 6
scalearray kArr, 1, 3
... change kArr from [1, 3, 9, 5, 6] to [1, 1.5, 3, 2, 2.25]. Here is a simple example:
EXAMPLE 03E18_scalearray.csd
<CsoundSynthesizer>
<CsOptions>
-nm0
</CsOptions>
<CsInstruments>
ksmps = 32
seed 0
instr 1
;create an array with 10 elements
kArr[] init 10
;fill in random numbers and print them out
printks "kArr in maximum range 0..100:\n", 0
kIndx = 0
until kIndx == 10 do
kNum random 0, 100
kArr[kIndx] = kNum
printf "kArr[%d] = %10f\n", kIndx+1, kIndx, kNum
kIndx += 1
od
;scale numbers 0...1 and print them out again
scalearray kArr, 0, 1
kIndx = 0
printks "kArr in range 0..1\n", 0
until kIndx == 10 do
printf "kArr[%d] = %10f\n", kIndx+1, kIndx, kArr[kIndx]
kIndx += 1
od
turnoff
endin
</CsInstruments>
<CsScore>
i1 0 0.1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
One possible output:
kArr in maximum range 0..100:
kArr[0] = 93.898027
kArr[1] = 98.554934
kArr[2] = 37.244273
kArr[3] = 58.581820
kArr[4] = 71.195263
kArr[5] = 11.948356
kArr[6] = 3.493777
kArr[7] = 13.688537
kArr[8] = 24.875835
kArr[9] = 52.205258
kArr in range 0..1
kArr[0] = 0.951011
kArr[1] = 1.000000
kArr[2] = 0.355040
kArr[3] = 0.579501
kArr[4] = 0.712189
kArr[5] = 0.088938
kArr[6] = 0.000000
kArr[7] = 0.107244
kArr[8] = 0.224929
kArr[9] = 0.512423
maparray applies the function "fun" (which needs to have one input and one output argument) to each element of the vector kArrSrc and stores the result in kArrRes (which needs to have been created previously):
kArrRes maparray kArrSrc, "fun"
Possible functions are for instance abs, ceil, exp, floor, frac, int, log, log10, round, sqrt. The following example applies different functions sequentially to the source array:
EXAMPLE 03E19_maparray.csd
<CsoundSynthesizer>
<CsOptions>
-nm0
</CsOptions>
<CsInstruments>
ksmps = 32
instr 1
;create an array and fill with numbers
kArrSrc[] array 1.01, 2.02, 3.03, 4.05, 5.08, 6.13, 7.21
;print source array
printf "%s", 1, "\nSource array:\n"
kndx = 0
until kndx == lenarray(kArrSrc) do
printf "kArrSrc[%d] = %f\n", kndx+1, kndx, kArrSrc[kndx]
kndx += 1
od
;create an empty array for the results
kArrRes[] init 7
;apply the sqrt() function to each element
kArrRes maparray kArrSrc, "sqrt"
;print the result
printf "%s", 1, "\nResult after applying sqrt() to source array\n"
kndx = 0
until kndx == lenarray(kArrRes) do
printf "kArrRes[%d] = %f\n", kndx+1, kndx, kArrRes[kndx]
kndx += 1
od
;apply the log() function to each element
kArrRes maparray kArrSrc, "log"
;print the result
printf "%s", 1, "\nResult after applying log() to source array\n"
kndx = 0
until kndx == lenarray(kArrRes) do
printf "kArrRes[%d] = %f\n", kndx+1, kndx, kArrRes[kndx]
kndx += 1
od
;apply the int() function to each element
kArrRes maparray kArrSrc, "int"
;print the result
printf "%s", 1, "\nResult after applying int() to source array\n"
kndx = 0
until kndx == lenarray(kArrRes) do
printf "kArrRes[%d] = %f\n", kndx+1, kndx, kArrRes[kndx]
kndx += 1
od
;apply the frac() function to each element
kArrRes maparray kArrSrc, "frac"
;print the result
printf "%s", 1, "\nResult after applying frac() to source array\n"
kndx = 0
until kndx == lenarray(kArrRes) do
printf "kArrRes[%d] = %f\n", kndx+1, kndx, kArrRes[kndx]
kndx += 1
od
;turn instrument instance off
turnoff
endin
</CsInstruments>
<CsScore>
i 1 0 0.1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
Prints:
Source array:
kArrSrc[0] = 1.010000
kArrSrc[1] = 2.020000
kArrSrc[2] = 3.030000
kArrSrc[3] = 4.050000
kArrSrc[4] = 5.080000
kArrSrc[5] = 6.130000
kArrSrc[6] = 7.210000
Result after applying sqrt() to source array
kArrRes[0] = 1.004988
kArrRes[1] = 1.421267
kArrRes[2] = 1.740690
kArrRes[3] = 2.012461
kArrRes[4] = 2.253886
kArrRes[5] = 2.475884
kArrRes[6] = 2.685144
Result after applying log() to source array
kArrRes[0] = 0.009950
kArrRes[1] = 0.703098
kArrRes[2] = 1.108563
kArrRes[3] = 1.398717
kArrRes[4] = 1.625311
kArrRes[5] = 1.813195
kArrRes[6] = 1.975469
Result after applying int() to source array
kArrRes[0] = 1.000000
kArrRes[1] = 2.000000
kArrRes[2] = 3.000000
kArrRes[3] = 4.000000
kArrRes[4] = 5.000000
kArrRes[5] = 6.000000
kArrRes[6] = 7.000000
Result after applying frac() to source array
kArrRes[0] = 0.010000
kArrRes[1] = 0.020000
kArrRes[2] = 0.030000
kArrRes[3] = 0.050000
kArrRes[4] = 0.080000
kArrRes[5] = 0.130000
kArrRes[6] = 0.210000
The dimension of an input array must be declared in two places:
For Instance:
opcode FirstEl, k, k[]
;returns the first element of vector kArr
kArr[] xin
xout kArr[0]
endop
This is a simple example using this code:
EXAMPLE 03E20_array_UDO.csd
<CsoundSynthesizer>
<CsOptions>
-nm128
</CsOptions>
<CsInstruments>
ksmps = 32
opcode FirstEl, k, k[]
;returns the first element of vector kArr
kArr[] xin
xout kArr[0]
endop
instr 1
kArr[] array 6, 3, 9, 5, 1
kFirst FirstEl kArr
printf "kFirst = %d\n", 1, kFirst
turnoff
endin
</CsInstruments>
<CsScore>
i 1 0 .1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
As there is no built-in opcode for printing the contents of an array, it is a good task for an array. Let us finish with an example that does just this:
EXAMPLE 03E21_print_array.csd
<CsoundSynthesizer>
<CsOptions>
-n -m0
</CsOptions>
<CsInstruments>
ksmps = 32
seed 0
opcode PrtArr1k, 0, k[]POVVO
kArr[], ktrig, kstart, kend, kprec, kppr xin
kprint init 0
kndx init 0
if ktrig > 0 then
kppr = (kppr == 0 ? 10 : kppr)
kend = (kend == -1 || kend == .5 ? lenarray(kArr) : kend)
kprec = (kprec == -1 || kprec == .5 ? 3 : kprec)
kndx = kstart
Sformat sprintfk "%%%d.%df, ", kprec+3, kprec
Sdump sprintfk "%s", "["
loop:
Snew sprintfk Sformat, kArr[kndx]
Sdump strcatk Sdump, Snew
kmod = (kndx+1-kstart) % kppr
if kmod == 0 && kndx != kend-1 then
printf "%s\n", kprint+1, Sdump
Sdump strcpyk " "
endif
kprint = kprint + 1
loop_lt kndx, 1, kend, loop
klen strlenk Sdump
Slast strsubk Sdump, 0, klen-2
printf "%s]\n", kprint+1, Slast
endif
endop
instr SimplePrinting
kArr[] fillarray 1, 2, 3, 4, 5, 6, 7
kPrint metro 1
prints "\nSimple Printing with defaults, once a second:\n"
PrtArr1k kArr, kPrint
endin
instr EatTheHead
kArr[] fillarray 1, 2, 3, 4, 5, 6, 7
kPrint metro 1
kStart init 0
prints "\nChanging the start index:\n"
if kPrint == 1 then
PrtArr1k kArr, 1, kStart
kStart += 1
endif
endin
instr EatTheTail
kArr[] fillarray 1, 2, 3, 4, 5, 6, 7
kPrint metro 1
kEnd init 7
prints "\nChanging the end index:\n"
if kPrint == 1 then
PrtArr1k kArr, 1, 0, kEnd
kEnd -= 1
endif
endin
instr PrintFormatted
;create an array with 24 elements
kArr[] init 24
;fill with random values
kndx = 0
until kndx == lenarray(kArr) do
kArr[kndx] rnd31 10, 0
kndx += 1
od
;print
prints "\nPrinting with precision=5 and 4 elements per row:\n"
PrtArr1k kArr, 1, 0, -1, 5, 4
printks "\n", 0
;turnoff after first k-cycle
turnoff
endin
</CsInstruments>
<CsScore>
i "SimplePrinting" 0 5
i "EatTheHead" 6 5
i "EatTheTail" 12 5
i "PrintFormatted" 18 1
</CsScore>
</CsoundSynthesizer>
;example by joachim heintz
Prints:
Simple Printing with defaults, once a second:
[ 1.000, 2.000, 3.000, 4.000, 5.000, 6.000, 7.000]
[ 1.000, 2.000, 3.000, 4.000, 5.000, 6.000, 7.000]
[ 1.000, 2.000, 3.000, 4.000, 5.000, 6.000, 7.000]
[ 1.000, 2.000, 3.000, 4.000, 5.000, 6.000, 7.000]
[ 1.000, 2.000, 3.000, 4.000, 5.000, 6.000, 7.000]
Changing the start index:
[ 1.000, 2.000, 3.000, 4.000, 5.000, 6.000, 7.000]
[ 2.000, 3.000, 4.000, 5.000, 6.000, 7.000]
[ 3.000, 4.000, 5.000, 6.000, 7.000]
[ 4.000, 5.000, 6.000, 7.000]
[ 5.000, 6.000, 7.000]
Changing the end index:
[ 1.000, 2.000, 3.000, 4.000, 5.000, 6.000, 7.000]
[ 1.000, 2.000, 3.000, 4.000, 5.000, 6.000]
[ 1.000, 2.000, 3.000, 4.000, 5.000]
[ 1.000, 2.000, 3.000, 4.000]
[ 1.000, 2.000, 3.000]
Printing with precision=5 and 4 elements per row:
[-6.02002, 1.55606, -7.25789, -3.43802,
-2.86539, 1.35237, 9.26686, 8.13951,
0.68799, 3.02332, -7.03470, 7.87381,
-4.86597, -2.42907, -5.44999, 2.07420,
1.00121, 7.33340, -7.53952, 3.23020,
9.93770, 2.84713, -8.23949, -1.12326]
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