generic text read function

[John Hunter]

>>>>> "les" == les ander <les_ander at yahoo.com> writes:

    les> Hi, matlab has a useful function called "textread" which I am
    les> trying to reproduce in python.

    les> two inputs: filename, format (%s for string, %d for integers,
    les> etc and arbitary delimiters)

    les> variable number of outputs (to correspond to the format given
    les> as input);

    les> So suppose your file looked like this str1 5 2.12 str1 3 0.11
    les> etc with tab delimited columns.  then you would call it as

    les> c1,c2,c3=textread(filename, '%s\t%d\t%f')

    les> Unfortunately I do not know how to read a line from a file
    les> using the line format given as above. Any help would be much
    les> appreciated les

Not an answer to your question, but I use a different approach to
solve this problem.  Here is a simple example

converters = (str, int, float)
results = []
for line in file(filename):
    line = line.strip()
    if not len(line): continue  # skip blank lines
    values = line.split('\t')
    if len(values) != len(converters):
        raise ValueError('Illegal line')
    results.append([func(val) for func, val in zip(converters, values)])

c1, c2, c3 = zip(*results)

If you really need to emulate the matlab command, perhaps this example
will give you an idea about how to get started.  Eg, set up a dict
mapping format strings to converter functions

d = {'%s' : str,
     '%d' : int,
     '%f' : float,
}

and then parse the format string to set up your converters and split function.

If you succeed in implementing this function, please consider sending
it to me as a contribution to matplotlib -- http://matplotlib.sf.net

Cheers,
JDH