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__all__ = ['savetxt', 'loadtxt',
'load', 'loads',
'save', 'savez',
'packbits', 'unpackbits',
import numpy as np
import format
import zipfile
import cStringIO
import tempfile
import os
from cPickle import load as _cload, loads
from _datasource import DataSource
from _compiled_base import packbits, unpackbits
_file = file
class BagObj(object):
"""A simple class that converts attribute lookups to
getitems on the class passed in.
def __init__(self, obj):
self._obj = obj
def __getattribute__(self, key):
return object.__getattribute__(self, '_obj')[key]
except KeyError:
raise AttributeError, key
class NpzFile(object):
"""A dictionary-like object with lazy-loading of files in the zipped
archive provided on construction.
The arrays and file strings are lazily loaded on either
getitem access using obj['key'] or attribute lookup using obj.f.key
A list of all files (without .npy) extensions can be obtained
with .files and the ZipFile object itself using .zip
def __init__(self, fid):
_zip = zipfile.ZipFile(fid)
self._files = _zip.namelist()
self.files = []
for x in self._files:
if x.endswith('.npy'):
self.files.append(x) = _zip
self.f = BagObj(self)
def __getitem__(self, key):
# FIXME: This seems like it will copy strings around
# more than is strictly necessary. The zipfile
# will read the string and then
# the format.read_array will copy the string
# to another place in memory.
# It would be better if the zipfile could read
# (or at least uncompress) the data
# directly into the array memory.
member = 0
if key in self._files:
member = 1
elif key in self.files:
member = 1
key += '.npy'
if member:
bytes =
if bytes.startswith(format.MAGIC_PREFIX):
value = cStringIO.StringIO(bytes)
return format.read_array(value)
return bytes
raise KeyError, "%s is not a file in the archive" % key
def load(file, memmap=False):
"""Load a binary file.
Read a binary file (either a pickle, or a binary .npy/.npz file) and
return the result.
file : file-like object or string
the file to read. It must support seek and read methods
memmap : bool
If true, then memory-map the .npy file or unzip the .npz file into
a temporary directory and memory-map each component
This has no effect for a pickle.
result : array, tuple, dict, etc.
data stored in the file.
If file contains pickle data, then whatever is stored in the pickle is
If the file is .npy file, then an array is returned.
If the file is .npz file, then a dictionary-like object is returned
which has a filename:array key:value pair for every file in the zip.
if isinstance(file, type("")):
fid = _file(file,"rb")
fid = file
if memmap:
raise NotImplementedError
# Code to distinguish from NumPy binary files and pickles.
_ZIP_PREFIX = 'PK\x03\x04'
N = len(format.MAGIC_PREFIX)
magic =,1) # back-up
if magic.startswith(_ZIP_PREFIX): # zip-file (assume .npz)
return NpzFile(fid)
elif magic == format.MAGIC_PREFIX: # .npy file
return format.read_array(fid)
else: # Try a pickle
return _cload(fid)
raise IOError, \
"Failed to interpret file %s as a pickle" % repr(file)
def save(file, arr):
"""Save an array to a binary file (a string or file-like object).
If the file is a string, then if it does not have the .npy extension,
it is appended and a file open.
Data is saved to the open file in NumPy-array format
import numpy as np
...'myfile', a)
a = np.load('myfile.npy')
if isinstance(file, str):
if not file.endswith('.npy'):
file = file + '.npy'
fid = open(file, "wb")
fid = file
arr = np.asanyarray(arr)
format.write_array(fid, arr)
def savez(file, *args, **kwds):
"""Save several arrays into an .npz file format which is a zipped-archive
of arrays
If keyword arguments are given, then filenames are taken from the keywords.
If arguments are passed in with no keywords, then stored file names are
arr_0, arr_1, etc.
if isinstance(file, str):
if not file.endswith('.npz'):
file = file + '.npz'
namedict = kwds
for i, val in enumerate(args):
key = 'arr_%d' % i
if key in namedict.keys():
raise ValueError, "Cannot use un-named variables and keyword %s" % key
namedict[key] = val
zip = zipfile.ZipFile(file, mode="w")
# Place to write temporary .npy files
# before storing them in the zip
direc = tempfile.gettempdir()
todel = []
for key, val in namedict.iteritems():
fname = key + '.npy'
filename = os.path.join(direc, fname)
fid = open(filename,'wb')
format.write_array(fid, np.asanyarray(val))
zip.write(filename, arcname=fname)
for name in todel:
# Adapted from matplotlib
def _getconv(dtype):
typ = dtype.type
if issubclass(typ, np.bool_):
return lambda x: bool(int(x))
if issubclass(typ, np.integer):
return int
elif issubclass(typ, np.floating):
return float
elif issubclass(typ, np.complex):
return complex
return str
def _string_like(obj):
try: obj + ''
except (TypeError, ValueError): return 0
return 1
def loadtxt(fname, dtype=float, comments='#', delimiter=None, converters=None,
skiprows=0, usecols=None, unpack=False):
Load ASCII data from fname into an array and return the array.
The data must be regular, same number of values in every row
fname can be a filename or a file handle. Support for gzipped files is
automatic, if the filename ends in .gz
See to read and write matfiles.
Example usage:
X = loadtxt('test.dat') # data in two columns
t = X[:,0]
y = X[:,1]
Alternatively, you can do the same with "unpack"; see below
X = loadtxt('test.dat') # a matrix of data
x = loadtxt('test.dat') # a single column of data
dtype - the data-type of the resulting array. If this is a
record data-type, the the resulting array will be 1-d and each row will
be interpreted as an element of the array. The number of columns
used must match the number of fields in the data-type in this case.
comments - the character used to indicate the start of a comment
in the file
delimiter is a string-like character used to seperate values in the
file. If delimiter is unspecified or none, any whitespace string is
a separator.
converters, if not None, is a dictionary mapping column number to
a function that will convert that column to a float. Eg, if
column 0 is a date string: converters={0:datestr2num}
skiprows is the number of rows from the top to skip
usecols, if not None, is a sequence of integer column indexes to
extract where 0 is the first column, eg usecols=(1,4,5) to extract
just the 2nd, 5th and 6th columns
unpack, if True, will transpose the matrix allowing you to unpack
into named arguments on the left hand side
t,y = load('test.dat', unpack=True) # for two column data
x,y,z = load('somefile.dat', usecols=(3,5,7), unpack=True)
if _string_like(fname):
if fname.endswith('.gz'):
import gzip
fh =
fh = file(fname)
elif hasattr(fname, 'seek'):
fh = fname
raise ValueError('fname must be a string or file handle')
X = []
dtype = np.dtype(dtype)
defconv = _getconv(dtype)
converterseq = None
if converters is None:
converters = {}
if dtype.names is not None:
converterseq = [_getconv(dtype.fields[name][0]) \
for name in dtype.names]
for i,line in enumerate(fh):
if i<skiprows: continue
line = line[:line.find(comments)].strip()
if not len(line): continue
vals = line.split(delimiter)
if converterseq is None:
converterseq = [converters.get(j,defconv) \
for j in xrange(len(vals))]
if usecols is not None:
row = [converterseq[j](vals[j]) for j in usecols]
row = [converterseq[j](val) for j,val in enumerate(vals)]
if dtype.names is not None:
row = tuple(row)
X = np.array(X, dtype)
r,c = X.shape
if r==1 or c==1:
X.shape = max([r,c]),
if unpack: return X.T
else: return X
# adjust so that fmt can change across columns if desired.
def savetxt(fname, X, fmt='%.18e',delimiter=' '):
Save the data in X to file fname using fmt string to convert the
data to strings
fname can be a filename or a file handle. If the filename ends in .gz,
the file is automatically saved in compressed gzip format. The load()
command understands gzipped files transparently.
Example usage:
save('test.out', X) # X is an array
save('test1.out', (x,y,z)) # x,y,z equal sized 1D arrays
save('test2.out', x) # x is 1D
save('test3.out', x, fmt='%1.4e') # use exponential notation
delimiter is used to separate the fields, eg delimiter ',' for
comma-separated values
if _string_like(fname):
if fname.endswith('.gz'):
import gzip
fh =,'wb')
fh = file(fname,'w')
elif hasattr(fname, 'seek'):
fh = fname
raise ValueError('fname must be a string or file handle')
X = np.asarray(X)
origShape = None
if len(X.shape)==1:
origShape = X.shape
X.shape = len(X), 1
for row in X:
fh.write(delimiter.join([fmt%val for val in row]) + '\n')
if origShape is not None:
X.shape = origShape
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