74 lines
2 KiB
Python
74 lines
2 KiB
Python
# This file is part of the micropython-ulab project, https://github.com/v923z/micropython-ulab
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#
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# The MIT License (MIT)
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#
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# Copyright (c) 2022 Zoltán Vörös
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import sys
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use_ulab = False
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try:
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from ubinascii import b2a_base64 as b64encode
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from ubinascii import hexlify
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import ujson as json
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from ulab import numpy as np
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use_ulab = True
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except:
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from base64 import b64encode
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import json
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import numpy as np
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from numpy.lib.format import dtype_to_descr
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def ulab_dtype_to_descr(dtype):
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desc = '>'
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if sys.byteorder == 'little':
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desc = '<'
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if dtype == ord('B'):
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desc = '|u1'
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elif dtype == ord('b'):
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desc = '|i1'
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elif dtype == ord('H'):
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desc = desc + 'u2'
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elif dtype == ord('h'):
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desc = desc + 'i2'
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elif dtype == ord('d'):
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desc = desc + 'f8'
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elif dtype == ord('f'):
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desc = desc + 'f4'
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elif dtype == ord('c'):
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desc = desc + 'c16'
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if np.array([1], dtype=np.float).itemsize == 4:
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desc = desc + 'c8'
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return desc
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def ndarray_to_json(obj, b64=True):
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"""
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Turn an ndarray into a json string, using either base64 encoding or hexify
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Returns a serialised dictionary with three keys:
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- dtype: a valid numpy dtype string (one of |u1, |i1, <u2, <i2, <f4, <f8, <c8, <c16, >u2, >i2, >f4, >f8, >c8, >c16)
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- array: the hexified, or base64-encoded raw data array
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- shape: the shape of the array (a list or tuple of integers)
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Usage:
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ndarray = np.array([1, 2, 3], dtype=np.uint8)
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ndarray_to_json(ndarray, b64=True)
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"""
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if not isinstance(obj, np.ndarray):
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raise TypeError('input argument must be an ndarray')
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if use_ulab:
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dtype_desciptor = ulab_dtype_to_descr(obj.dtype)
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else:
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dtype_desciptor = dtype_to_descr(obj.dtype)
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if not b64:
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data = hexlify(obj.tobytes())
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else:
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data = b64encode(obj.tobytes())
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return json.dumps({'array': data, 'dtype': dtype_desciptor, 'shape': obj.shape})
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