Re: Reading floating point data with Python
Mike Tibbs (tibbs@dopey.si.com)
Sun, 10 Apr 1994 14:19:17 GMT
In article <CnqvK2.KBG@murdoch.acc.Virginia.EDU>, sdm7g@elvis.med.Virginia.EDU
(Steven D. Majewski) writes:
|> In article <2nn4pe$ksd@news.umbc.edu>,
|> L. Larrabee Strow <strow@umbc.edu> wrote:
|> >Is there any existing way to read files containing binary floating
|> >point data with Python?
|> >
|> >It sure would be nice to have fread/fwrite type capabilities.
|> >Reformatting floating point data files to ascii, reading them , and
|> >using atof is not an option due to space and performance problems.
|> >
|>
|> Look at builtin modules array and struct.
|>
|> >>> from array import array
|> >>> a = array( 'f' )
|>
|> Will create an extendible floating point array with methods:
|>
|> ['append', 'byteswap', 'fromfile', 'fromlist', 'fromstring',
|> 'insert', 'read', 'reverse', 'tofile', 'tolist', 'tostring', 'write']
|>
|> Arrays also have __getitem__ and __setitem__ methods defined, so you
|> can access their elements just like lists.
|>
|> a[0] is the first element; a[-1] is the last.
|> ( "a = array( 'f' )" creates an empty array, so, just as for an empty
|> list [], a[0] will generate an IndexError. a = array( 'f', [1,2,3] )
|> will create an array initialized with three values. )
|>
|> a.fromfile( open( filename, 'r' ) , 1000 )
|> will read in 1000 binary values from filename into array a.
|> ( fromfile, fromstring, and fromlist all append values to the end
|> of the array, extending it's size. )
What is the format of 'filename' exactly? Is it just a stream of binary
floating point values?
How would you create such a file in python?
-- Mike Tibbs