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import numpy as np
def interp1d(src_start, src_step, src_val, dst_coords, stencil):
idx_src = (dst_coords / src_step - src_start - (stencil / 2 - 1)).astype(np.int)
src_coord = np.linspace(src_start, src_start + src_step * (src_val.shape[0] - 1),
src_val.shape[0], dtype = src_val.dtype)
fact = np.zeros((stencil, ) + idx_src.shape, dtype = src_val.dtype) + 1.0
for i in range(stencil):
for j in range(stencil):
if i == j:
continue
fact[i] *= (dst_coords - src_coord[idx_src + j]) / (src_coord[idx_src + i] - src_coord[idx_src + j])
ret = np.zeros_like(dst_coords, dtype = src_val.dtype)
for i in range(stencil):
ret += fact[i] * src_val[idx_src + i]
return ret
def interp2d(src_start, src_step, src_val, dst_coords, stencil):
ret = np.zeros_like(dst_coords[0], dtype = src_val.dtype)
idx_src = []
fact = []
for dim in range(len(src_start)):
src_coord = np.linspace(src_start[dim], src_start[dim] + src_step[dim] * (src_val.shape[dim] - 1),
src_val.shape[dim], dtype = src_val.dtype)
idx = ((dst_coords[dim] - src_start[dim]) / src_step[dim] - (stencil / 2 - 1)).astype(np.int)
f = np.zeros((stencil, ) + idx.shape, dtype = src_val.dtype) + 1.0
for i in range(stencil):
for j in range(stencil):
if i == j:
continue
f[i] *= (dst_coords[dim] - src_coord[idx + j]) / (src_coord[idx + i] - src_coord[idx + j])
idx_src.append(idx)
fact.append(f)
for i in range(stencil):
val = np.zeros_like(ret)
for j in range(stencil):
val += fact[1][j] * src_val[idx_src[0] + i, idx_src[1] + j]
ret += fact[0][i] * val
return ret
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