#!/usr/bin/python2.6

"""
Tool for filtering a tabular data file. Fields are separated by tabs, the 
header line is denoted by a '#' in the first byte, comments are denoted by
a '#' at the start of any subsequent line.

Expressions can use column names as well as numbers. The -c options allows
cutting, again using field name or numbers.

usage: %prog expression < table 
    -H, --header:       keep header in output
    -C, --comments:     keep comments in output
    --force-header:     assume the first line is a header even if it does not start with "#"
    -c, --cols=1,2:     names or indexes of columns to keep
"""

import psyco_full

import sys

import sys
import bx.tabular.io
from bx.cookbook import doc_optparse

def __main__():

    # Parse command line arguments
    options, args = doc_optparse.parse( __doc__ )
    try:
        keep_header = bool( options.header )
        keep_comments = bool( options.comments )
        cols = []
        if options.cols:
            for c in options.cols.split( ',' ):
                try:
                    v = int( c )
                except:
                    v = c
                cols.append( c )
        if len( args ) > 0:
            expr = args[0]
        else:
            expr = None
        if options.force_header:
            force_header = bx.tabular.io.FIRST_LINE_IS_HEADER
        else:
            force_header = None
    except:
        doc_optparse.exception()

    # Compile expression for SPEED
    if expr: expr = compile( expr, '<expr arg>', 'eval' )

    for element in bx.tabular.io.TableReader( sys.stdin, force_header=force_header ):
        if type( element ) is bx.tabular.io.Header:
            if keep_header: 
                if cols:
                    print "#" + "\t".join( element[c] for c in cols )
                else:
                    print element
        elif type( element ) is bx.tabular.io.Comment:
            if keep_comments: 
                print element
        else:
            if expr is None or bool( eval( expr, dict( row=element ) ) ):
                if cols:
                    print "\t".join( [ element[c] for c in cols ] )
                else:
                    print element

if __name__ == "__main__": __main__()
