Assign Wave By Index

// AssignWave(SourceWave,DestWave,IndexWave,Mode)
// Quick wave assignment according to an index wave.
// Mode specifies how to interpret the index wave and assign values.
// Mode = 1: DestWave[i] = SourceWave[i]
//                          N(Source) = N(Dest) (IndexWave ignored - just pass a null reference)
// Mode = 2: DestWave[i] = SourceWave[IndexWave[i]]
//                          N(Source) = N(Dest) = N(Index)
// Mode = 3: DestWave[IndexWave[i]] = SourceWave[IndexWave[i]]
//                          N(Source) = N(Dest)
// Mode = 4: DestWave[IndexWave[i]] = SourceWave[i]
//                          N(Source) = N(Index)
//
// For Modes 1 and 2, IndexWave is the index into SourceWave.
// For Modes 3 and 4, IndexWave is the index into DestWave.
Function AssignWave(SourceWave,DestWave,IndexWave,Mode)
    WAVE DestWave,SourceWave
    WAVE IndexWave
    Variable Mode
    switch (Mode)
        case 1: // Functional equivalent to DestWave[i] = SourceWave[i]
            if (WaveType(DestWave,1)==2) // text wave; no MatrixOp support
                DestWave = SourceWave
            else // Faster than: DestWave = SourceWave[IndexWave]
                if (WaveType(DestWave) & 0x01) // is complex?
                    FastOp/C DestWave = SourceWave
                else
                    FastOp DestWave = SourceWave               
                endif
            endif
            break
        case 2: // Functional equivalent to DestWave[i] = SourceWave[IndexWave[i]]
            if (WaveType(DestWave,1)==2) // text wave; no MatrixOp support
                DestWave = SourceWave[IndexWave]
            else // Faster than: DestWave = SourceWave[IndexWave]
                if (WaveType(DestWave) & 0x01) // is complex?
                    MatrixOp/O/C DestWave = waveMap(SourceWave,IndexWave)
                else
                    MatrixOp/O DestWave = waveMap(SourceWave,IndexWave)
                endif
            endif
            break
        case 3: // Functional equivalent to DestWave[IndexWave[i]] = SourceWave[IndexWave[i]]
            if (WaveType(DestWave,1)==2) // text wave
                Make/T/O/N=(numpnts(IndexWave))/FREE DummyDestText
                DummyDestText = AssignWave_WaveMapText(SourceWave,DestWave,IndexWave,IndexWave)
            else // real or complex
                Make/O/N=(numpnts(IndexWave))/FREE DummyDestNum
                DummyDestNum = AssignWave_WaveMapNum(SourceWave,DestWave,IndexWave,IndexWave)
            endif
            break
        case 4: // Functional equivalent to DestWave[IndexWave[i]] = SourceWave[i]
            Make/O/N=(numpnts(SourceWave))/FREE SourceIndexWave = p
            if (WaveType(DestWave,1)==2) // text wave
                Make/T/O/N=(numpnts(IndexWave))/FREE DummyDestText
                DummyDestText = AssignWave_WaveMapText(SourceWave,DestWave,SourceIndexWave,IndexWave)
            else // real or complex
                Make/O/N=(numpnts(IndexWave))/FREE DummyDestNum
                DummyDestNum = AssignWave_WaveMapNum(SourceWave,DestWave,SourceIndexWave,IndexWave)            
            endif
            break
    endswitch
End

// Maps a source value into a destination value.
// Used by AssignWave (Modes 3 or 4).  (For mode 3, srcidx = destidx)
// Suggested by Fernando on the Igor discussion list (7/20-21/12)
Function AssignWave_WaveMapNum(wSource, wDest, srcidx, destidx)
    Wave/C wSource, wDest // complex, in general; also works for real
    Variable srcidx,destidx

    wDest[destidx] = wSource[srcidx]
End

Function/S AssignWave_WaveMapText(wSource, wDest, srcidx, destidx)
    Wave/T wSource, wDest
    Variable srcidx, destidx

    wDest[destidx] = wSource[srcidx]
End