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maparray

Apply a function of one argument to every element of a vector (one-dimensional k-rate array).

📝 Note

Up to Csound 6, maparrayi was called maparray_i.

Syntax

karray = maparray(kinarray, String)
karray = maparrayi(kinarray, String)

karray maparray kinarray, String
karray maparray_i kinarray, String

Initialization

String -- a string that names an opcode function, at i-rate for maparrayi or k-rate for maparray.

Performance

karray -- array for answers.

kinarray -- array for arguments to the function.

Replacing tabmap and tabmap_i

tabmap maps a k-rate array during initialization and on each control cycle. Change kResult = tabmap(kSource, "abs") to kResult = maparray(kSource, "abs").

tabmap_i and its alias tabmapi run only at initialization. Replace either name with maparrayi to keep that timing. maparray_i is the older spelling of maparrayi.

The source must be initialized and one-dimensional. Use a supported one-input scalar function such as abs. Initialization-only mapping requires its i-rate form. Repeated k-rate mapping needs both i-rate and k-rate forms. This is not an interface for arbitrary stateful opcodes.

Examples

Here is an example of the maparray opcode. It uses the file maparray-modern.csd.

Example of the maparray opcode.
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<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-n
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 32
nchnls = 2
0dbfs  = 1

instr 1
  ;create an array and fill with numbers
  ArrSrc:k[] = fillarray(1.01, 2.02, 3.03, 4.05, 5.08, 6.13, 7.21)

  ;print source array
  printf("%s", 1, "\nSource array:\n")
  ndx:k = 0
  until ndx == lenarray(ArrSrc) do
    printf("ArrSrc[%d] = %f\n", ndx+1, ndx, ArrSrc[ndx])
    ndx += 1
  od

  ;create an empty array for the results
  ArrRes:k[] = init(7)

  ;apply the sqrt() function to each element
  ArrRes = maparray(ArrSrc, "sqrt")

  ;print the result
  printf("%s", 1, "\nResult after applying sqrt() to source array\n")
  ndx = 0
  until ndx == lenarray(ArrRes) do
    printf("ArrRes[%d] = %f\n", ndx+1, ndx, ArrRes[ndx])
    ndx += 1
  od

  ;apply the log() function to each element
  ArrRes = maparray(ArrSrc, "log")

  ;print the result
  printf("%s", 1, "\nResult after applying log() to source array\n")
  ndx = 0
  until ndx == lenarray(ArrRes) do
    printf("ArrRes[%d] = %f\n", ndx+1, ndx, ArrRes[ndx])
    ndx += 1
  od

  ;apply the int() function to each element
  ArrRes = maparray(ArrSrc, "int")

  ;print the result
  printf("%s", 1, "\nResult after applying int() to source array\n")
  ndx = 0
  until ndx == lenarray(ArrRes) do
    printf("ArrRes[%d] = %f\n", ndx+1, ndx, ArrRes[ndx])
    ndx += 1
  od

  ;apply the frac() function to each element
  ArrRes = maparray(ArrSrc, "frac")

  ;print the result
  printf("%s", 1, "\nResult after applying frac() to source array\n")
  ndx = 0
  until ndx == lenarray(ArrRes) do
    printf("ArrRes[%d] = %f\n", ndx+1, ndx, ArrRes[ndx])
  ndx += 1
  od

  ;turn instrument instance off
  turnoff()
endin

</CsInstruments>
<CsScore>
i 1 0 0.1
e
</CsScore>
</CsoundSynthesizer>

Here is an example of the maparray opcode. It uses the file maparray.csd.

Example of the maparray opcode.
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<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-n
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 32
nchnls = 2
0dbfs  = 1

instr 1

;create an array and fill with numbers
kArrSrc[] fillarray 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
e
</CsScore>
</CsoundSynthesizer>

See Also

Array opcodes

Credits

Author: John ffitch
Codemist Ltd
2013

New in version 6.00