Source code for

Input/output routines common to many file formats.


import bz2
import gzip

import numpy as np
import netCDF4

[docs]def prepare_for_read(filename): """ Return a file like object read for reading. Open a file for reading in binary mode with transparent decompression of Gzip and BZip2 files. The resulting file-like object should be closed. Parameters ---------- filename : str or file-like object Filename or file-like object which will be opened. File-like objects will not be examined for compressed data. Returns ------- file_like : file-like object File like object from which data can be read. """ # if a file-like object was provided, return if hasattr(filename, 'read'): # file-like object return filename # look for compressed data by examining the first few bytes fh = open(filename, 'rb') magic = fh.close() if magic.startswith(b'\x1f\x8b'): return gzip.GzipFile(filename, 'rb') if magic.startswith(b'BZh'): return bz2.BZ2File(filename, 'rb') return open(filename, 'rb')
def stringarray_to_chararray(arr, numchars=None): """ Convert an string array to a character array with one extra dimension. Parameters ---------- arr : array Array with numpy dtype 'SN', where N is the number of characters in the string. numchars : int Number of characters used to represent the string. If numchar > N the results will be padded on the right with blanks. The default, None will use N. Returns ------- chararr : array Array with dtype 'S1' and shape = arr.shape + (numchars, ). """ carr = netCDF4.stringtochar(arr) if numchars is None: return carr arr_numchars = carr.shape[-1] if numchars <= arr_numchars: raise ValueError('numchars must be >= %i' % (arr_numchars)) chararr = np.zeros(arr.shape + (numchars, ), dtype='S1') chararr[..., :arr_numchars] = carr[:] return chararr def _test_arguments(dic): """ Issue a warning if receive non-empty argument dict. """ if dic: import warnings warnings.warn('Unexpected arguments: %s' % dic.keys()) def make_time_unit_str(dtobj): """ Return a time unit string from a datetime object. """ return "seconds since " + dtobj.strftime("%Y-%m-%dT%H:%M:%SZ")