| """Minimal .npy reader (format v1/v2, little-endian float64/float32, C order). Stdlib only; refuses object arrays, so a |
| pickled payload can never be executed. Returns (shape, flat list).""" |
| import ast |
| import struct |
|
|
|
|
| def read(path): |
| with open(path, "rb") as f: |
| magic = f.read(6) |
| if magic != b"\x93NUMPY": |
| raise ValueError("not an npy file") |
| major = f.read(2)[0] |
| hlen = struct.unpack("<H" if major == 1 else "<I", f.read(2 if major == 1 else 4))[0] |
| header = ast.literal_eval(f.read(hlen).decode("latin1")) |
| descr, fortran, shape = header["descr"], header["fortran_order"], tuple(header["shape"]) |
| if descr not in ("<f8", "<f4") or fortran: |
| raise ValueError("unsupported npy dtype/order: %s fortran=%s" % (descr, fortran)) |
| n = 1 |
| for d in shape: |
| n *= d |
| size = 8 if descr == "<f8" else 4 |
| raw = f.read(n * size) |
| vals = struct.unpack("<%d%s" % (n, "d" if size == 8 else "f"), raw) |
| return shape, vals |
|
|
|
|
| def column(path, col=0): |
| shape, vals = read(path) |
| rows, cols = (shape[0], shape[1]) if len(shape) == 2 else (shape[0], 1) |
| return [vals[i * cols + col] for i in range(rows)] |
|
|
