[Numpy-discussion] apply table lookup to each element
Neal Becker
ndbecker2@gmail....
Fri May 1 13:28:48 CDT 2009
Suggestion for efficient way to apply a table lookup to each element of an
integer array?
import numpy as np
_cos = np.empty ((2**rom_in_bits,), dtype=int)
_sin = np.empty ((2**rom_in_bits,), dtype=int)
for address in xrange (2**12):
_cos[address] = nint ((2.0**(rom_out_bits-1)-1) * cos (2 * pi * address
* (2.0**-rom_in_bits)))
_sin[address] = nint ((2.0**(rom_out_bits-1)-1) * sin (2 * pi * address
* (2.0**-rom_in_bits)))
Now _cos, _sin are arrays of integers (quantized sin, cos lookup tables)
How to apply _cos lookup to each element of an integer array:
phase = np.array (..., dtype =int)
cos_out = lookup (phase, _cos) ???
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