def main(argv=None):
    """script main.

    parses command line options in sys.argv, unless *argv* is given.
    """

    if argv is None:
        argv = sys.argv

    parser = E.OptionParser(
        version="%prog version: $Id: r_mann_whitney_u.py 2782 2009-09-10 11:40:29Z andreas $")

    parser.add_option("-m", "--method", dest="method", type="string",
                      help="method to use [ks=Kolmogorov-Smirnov,mwu=Mann-WhitneyU]")
    parser.add_option("-a", "--hardcopy", dest="hardcopy", type="string",
                      help="write hardcopy to file.", metavar="FILE")
    parser.add_option("-1", "--infile1", dest="filename_input1", type="string",
                      help="input filename for distribution 1.")
    parser.add_option("-2", "--infile2", dest="filename_input2", type="string",
                      help="input filename for distribution 2.")
    parser.add_option("-p", "--infile-map", dest="filename_input_map", type="string",
                      help="input filename for mapping categories to values.")

    parser.set_defaults(
        method="ks",
        filename_input1=None,
        filename_input2=None,
        filename_input_map=None,
    )

    (options, args) = E.Start(parser,
                              add_pipe_options=True)

    map_category2value = {}
    if options.filename_input_map:
        map_category2value = IOTools.ReadMap(open(options.filename_input_map, "r"),
                                             map_functions=(str, float))

    values1, errors1 = IOTools.ReadList(open(options.filename_input1, "r"),
                                        map_category=map_category2value)
    values2, errors2 = IOTools.ReadList(open(options.filename_input2, "r"),
                                        map_category=map_category2value)

    E.info("ninput1=%i, nerrors1=%i, ninput2=%i, nerrors2=%i" % (len(values1), len(errors1),
                                                                 len(values2), len(errors2)))

    if options.hardcopy:
        R.png(options.hardcopy, width=1024, height=768)

    if options.method == "ks":
        result = R.ks_test(values1, values2)
    elif options.method == "mwu":
        result = R.wilcox_test(values1, values2, paired=False)

    R.assign("v1", values1)
    R.assign("v2", values2)

    R.layout(R.matrix((1, 2, 3, 4), 2, 2, byrow=True))

    R.boxplot(values1, values2, col=('white', 'red'), main="Boxplot")

    R("""qqplot( v1, v2, main ='Quantile-quantile plot' ); lines( c(0,1), c(0,1) );""")

    R("""hist( v1, freq=FALSE, width=0.5, density=10, main='Relative frequency histogram')""")
    R("""hist( v2, freq=FALSE, add=TRUE,   width=0.5, col='red', offset=0.5, density=20, angle=135)""")
    R("""hist( v1, freq=TRUE,  width=0.5, density=10, main='Absolute frequency histogram')""")
    R("""hist( v2, freq=TRUE,  add=TRUE,   width=0.5, col='red', offset=0.5, density=20, angle=135)""")

    print "## Results for %s" % result['method']
    for x in ['p.value', 'statistic', 'alternative', 'method']:
        print x, result[x]

    E.Stop()
dataset/ETHPy150Open CGATOxford/cgat/scripts/r_mann_whitney_u.py/main/original