Mercurial > pylearn
annotate pylearn/io/filetensor.py @ 1394:48e8292e22e7
new version _read_header for filetensor that allow to work gzip file.
author | Frederic Bastien <nouiz@nouiz.org> |
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date | Fri, 07 Jan 2011 11:42:38 -0500 |
parents | 8ecc6da87350 |
children | e06c0ff46d2a |
rev | line source |
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33 | 1 """ |
2 Read and write the matrix file format described at | |
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3 U{http://www.cs.nyu.edu/~ylclab/data/norb-v1.0/index.html} |
33 | 4 |
5 The format is for dense tensors: | |
6 | |
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7 - magic number indicating type and endianness - 4bytes |
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8 - rank of tensor - int32 |
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9 - dimensions - int32, int32, int32, ... |
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10 - <data> |
33 | 11 |
12 The number of dimensions and rank is slightly tricky: | |
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13 - for scalar: rank=0, dimensions = [1, 1, 1] |
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14 - for vector: rank=1, dimensions = [?, 1, 1] |
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15 - for matrix: rank=2, dimensions = [?, ?, 1] |
33 | 16 |
17 For rank >= 3, the number of dimensions matches the rank exactly. | |
18 | |
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19 |
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20 @todo: add complex type support |
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21 |
33 | 22 """ |
23 import sys | |
24 import numpy | |
25 | |
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26 def _prod(lst): |
33 | 27 p = 1 |
28 for l in lst: | |
29 p *= l | |
30 return p | |
31 | |
32 _magic_dtype = { | |
33 0x1E3D4C51 : ('float32', 4), | |
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34 #0x1E3D4C52 : ('packed matrix', 0), #what is a packed matrix? |
33 | 35 0x1E3D4C53 : ('float64', 8), |
36 0x1E3D4C54 : ('int32', 4), | |
35 | 37 0x1E3D4C55 : ('uint8', 1), |
33 | 38 0x1E3D4C56 : ('int16', 2), |
39 } | |
40 _dtype_magic = { | |
41 'float32': 0x1E3D4C51, | |
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42 #'packed matrix': 0x1E3D4C52, |
33 | 43 'float64': 0x1E3D4C53, |
44 'int32': 0x1E3D4C54, | |
35 | 45 'uint8': 0x1E3D4C55, |
33 | 46 'int16': 0x1E3D4C56 |
47 } | |
48 | |
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49 def _read_int32(f): |
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50 """unpack a 4-byte integer from the current position in file f""" |
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51 s = f.read(4) |
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52 s_array = numpy.fromstring(s, dtype='int32') |
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53 return s_array.item() |
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54 |
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55 def _read_header(f, debug=False, fromgzip=False): |
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56 """ |
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57 :returns: data type, element size, rank, shape, size |
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58 """ |
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59 #what is the data type of this matrix? |
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60 #magic_s = f.read(4) |
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61 #magic = numpy.fromstring(magic_s, dtype='int32') |
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62 magic = _read_int32(f) |
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63 magic_t, elsize = _magic_dtype[magic] |
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64 if debug: |
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65 print 'header magic', magic, magic_t, elsize |
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66 if magic_t == 'packed matrix': |
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67 raise NotImplementedError('packed matrix not supported') |
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68 |
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69 #what is the rank of the tensor? |
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70 ndim = _read_int32(f) |
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71 if debug: print 'header ndim', ndim |
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72 |
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73 #what are the dimensions of the tensor? |
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74 if fromgzip: |
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75 d = f.read(max(ndim,3)*4) |
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76 dim = numpy.fromstring(d, dtype='int32')[:ndim] |
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77 else: |
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78 dim = numpy.fromfile(f, dtype='int32', count=max(ndim,3))[:ndim] |
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79 dim_size = _prod(dim) |
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80 if debug: print 'header dim', dim, dim_size |
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81 |
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82 return magic_t, elsize, ndim, dim, dim_size |
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83 |
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84 class arraylike(object): |
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85 """Provide an array-like interface to the filetensor in f. |
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86 |
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87 The rank parameter to __init__ controls how this object interprets the underlying tensor. |
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88 Its behaviour should be clear from the following example. |
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89 Suppose the underlying tensor is MxNxK. |
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90 |
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91 - If rank is 0, self[i] will be a scalar and len(self) == M*N*K. |
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92 |
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93 - If rank is 1, self[i] is a vector of length K, and len(self) == M*N. |
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94 |
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95 - If rank is 3, self[i] is a 3D tensor of size MxNxK, and len(self)==1. |
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96 |
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97 - If rank is 5, self[i] is a 5D tensor of size 1x1xMxNxK, and len(self) == 1. |
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98 |
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99 |
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100 :note: Objects of this class generally require exclusive use of the underlying file handle, because |
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101 they call seek() every time you access an element. |
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102 """ |
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103 |
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104 f = None |
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105 """File-like object""" |
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106 |
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107 magic_t = None |
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108 """numpy data type of array""" |
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109 |
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110 elsize = None |
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111 """number of bytes per scalar element""" |
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112 |
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113 ndim = None |
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114 """Rank of underlying tensor""" |
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115 |
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116 dim = None |
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117 """tuple of array dimensions (aka shape)""" |
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118 |
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119 dim_size = None |
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120 """number of scalars in the tensor (prod of dim)""" |
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121 |
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122 f_start = None |
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123 """The file position of the first element of the tensor""" |
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124 |
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125 readshape = None |
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126 """tuple of array dimensions of the block that we read""" |
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127 |
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128 readsize = None |
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129 """number of elements we must read for each block""" |
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130 |
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131 def __init__(self, f, rank=0, debug=False): |
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132 self.f = f |
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133 self.magic_t, self.elsize, self.ndim, self.dim, self.dim_size = _read_header(f,debug) |
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134 self.f_start = f.tell() |
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135 |
818 | 136 if rank <= self.ndim: |
137 self.readshape = tuple(self.dim[self.ndim-rank:]) | |
138 else: | |
139 self.readshape = tuple(self.dim) | |
140 | |
141 #self.readshape = tuple(self.dim[self.ndim-rank:]) if rank <= self.ndim else tuple(self.dim) | |
142 | |
143 if rank <= self.ndim: | |
144 padding = tuple() | |
145 else: | |
146 padding = (1,) * (rank - self.ndim) | |
147 | |
148 #padding = tuple() if rank <= self.ndim else (1,) * (rank - self.ndim) | |
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149 self.returnshape = padding + self.readshape |
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150 self.readsize = _prod(self.readshape) |
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151 if debug: print 'READ PARAM', self.readshape, self.returnshape, self.readsize |
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152 |
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153 def __len__(self): |
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154 return _prod(self.dim[:self.ndim-len(self.readshape)]) |
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155 |
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156 def __getitem__(self, idx): |
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157 if idx >= len(self): |
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158 raise IndexError(idx) |
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159 self.f.seek(self.f_start + idx * self.elsize * self.readsize) |
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160 return numpy.fromfile(self.f, |
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161 dtype=self.magic_t, |
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162 count=self.readsize).reshape(self.returnshape) |
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163 |
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164 |
33 | 165 # |
166 # TODO: implement item selection: | |
167 # e.g. load('some mat', subtensor=(:6, 2:5)) | |
168 # | |
169 # This function should be memory efficient by: | |
170 # - allocating an output matrix at the beginning | |
171 # - seeking through the file, reading subtensors from multiple places | |
172 def read(f, subtensor=None, debug=False): | |
173 """Load all or part of file 'f' into a numpy ndarray | |
174 | |
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175 @param f: file from which to read |
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176 @type f: file-like object |
33 | 177 |
178 If subtensor is not None, it should be like the argument to | |
179 numpy.ndarray.__getitem__. The following two expressions should return | |
180 equivalent ndarray objects, but the one on the left may be faster and more | |
181 memory efficient if the underlying file f is big. | |
182 | |
183 read(f, subtensor) <===> read(f)[*subtensor] | |
184 | |
185 Support for subtensors is currently spotty, so check the code to see if your | |
186 particular type of subtensor is supported. | |
187 | |
188 """ | |
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189 magic_t, elsize, ndim, dim, dim_size = _read_header(f,debug) |
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190 f_start = f.tell() |
33 | 191 |
192 rval = None | |
193 if subtensor is None: | |
248
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194 rval = numpy.fromfile(f, dtype=magic_t, count=_prod(dim)).reshape(dim) |
33 | 195 elif isinstance(subtensor, slice): |
196 if subtensor.step not in (None, 1): | |
197 raise NotImplementedError('slice with step', subtensor.step) | |
198 if subtensor.start not in (None, 0): | |
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199 bytes_per_row = _prod(dim[1:]) * elsize |
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200 f.seek(f_start+subtensor.start * bytes_per_row) |
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201 dim[0] = min(dim[0], subtensor.stop) - subtensor.start |
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202 rval = numpy.fromfile(f, dtype=magic_t, count=_prod(dim)).reshape(dim) |
33 | 203 else: |
204 raise NotImplementedError('subtensor access not written yet:', subtensor) | |
205 | |
206 return rval | |
207 | |
208 def write(f, mat): | |
248
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209 """Write a numpy.ndarray to file. |
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210 |
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211 @param f: file into which to write |
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212 @type f: file-like object |
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213 |
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214 @param mat: array to write to file |
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215 @type mat: numpy ndarray or compatible |
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216 |
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217 """ |
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218 def _write_int32(f, i): |
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219 i_array = numpy.asarray(i, dtype='int32') |
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220 if 0: print 'writing int32', i, i_array |
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221 i_array.tofile(f) |
33 | 222 |
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223 try: |
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224 _write_int32(f, _dtype_magic[str(mat.dtype)]) |
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225 except KeyError: |
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226 raise TypeError('Invalid ndarray dtype for filetensor format', mat.dtype) |
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227 |
33 | 228 _write_int32(f, len(mat.shape)) |
229 shape = mat.shape | |
230 if len(shape) < 3: | |
231 shape = list(shape) + [1] * (3 - len(shape)) | |
248
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232 if 0: print 'writing shape =', shape |
33 | 233 for sh in shape: |
234 _write_int32(f, sh) | |
235 mat.tofile(f) | |
236 |