Re: generic text read function

[Michael Spencer]

John Hunter wrote:
"les" == les ander <[EMAIL PROTECTED]> 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)
Builing on John's solution, this is still not quite what you're looking for (the 
delimiter preference is set for the whole line as a separate argument), but it's 
one step closer, and may give you some ideas:

import re
dispatcher = {'%s' : str,
              '%d' : int,
              '%f' : float,
                }
parser = re.compile("|".join(dispatcher))
def textread(iterable, formats, delimiter = None):
    # Splits on any combination of one or more chars in delimeter
    # or whitespace by default
    splitter = re.compile("[%s]+" % (delimiter or r"\s"))
    # Parse the format string into a list of converters
    # Note that white space in the format string is ignored
    # unlike the spec which calls for significant delimiters
    try:
        converters = [dispatcher[format] for format in parser.findall(formats)]
    except KeyError, err:
        raise KeyError, "Unrecogized format: %s" % err
    format_length = len(converters)
    iterator = iter(iterable)
    # Use any line-based iterable - like file
    for line in iterator:
        cols = re.split(splitter, line)
        if len(cols) != format_length:
            raise ValueError, "Illegal line: %s" % cols
        yield [func(val) for func, val in zip(converters, cols)]
# Example Usage:
source1 = """Item  5  8.0
Item2 6 9.0"""
source2 = """Item 1 \t42
Item 2\t43"""
 >>> for i in textread(source1.splitlines(),"%s %d %f"): print i
 ...
 ['Item', 5, 8.0]
 ['Item2', 6, 9.0]
 >>> for i in textread(source2.splitlines(),"%s %f", "\t"): print i
 ...
 ['Item 1 ', 42.0]
 ['Item 2', 43.0]
 >>> for item, value in textread(source2.splitlines(),"%s %f", "\t"): print 
item, value
 ...
 Item 1  42.0
 Item 2 43.0
 >>>

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