""" datatools.py
    c odenthal
    2005/05/30

    This module contains some data manipulation functions.
"""

from __future__ import division

def sortByKey(dct,ascending=True):
    """ Returns a list containing the (key,value) pairs
        of the dictionary 'dct' sorted by key.
    """
    lst = dct.items()
    lst.sort()
    if not ascending:
        lst.reverse()
    return lst

def sortByValue(dct,ascending=False):
    """ Returns a list containing the (key,value) pairs
        of the dictionary 'dct' sorted by value.
    """
    lst = [(v,k) for k,v in dct.items()]
    lst.sort()
    if not ascending:
        lst.reverse()
    return [(k,v) for v,k in lst]

def dict2array(dct,rowkeys,colkeys):
    """ This takes a dictionary 'dct' with keys of the form
        'cd' where 'c' and 'd' are letters. The output is a
        string that displays the entries of 'dct' as an array
        with the rows ordered by 'rowkeys' and the columns
        ordered by 'colkeys'. The assumption is that the
        values in 'dct' are less than 5. These values are
        multiplied by 200 and rounded (truncated?) to integer
        values that will be between 0 and 99.
    """
    # Form the array.
    lst = [[dct.get(r+c,0) for c in colkeys]
                           for r in rowkeys]

    # Scale the entries and truncate to integers.
    scale = lambda x : int(200*x)
    lst = [map(scale,row) for row in lst]

    # Convert the entries to strings.
    lst = [map(str,row) for row in lst]

    # Right-justify the entries.
    format = lambda s: s.rjust(3)
    lst = [map(format,row) for row in lst]

    # Insert the row labels.
    lst = [[rowkeys[i].center(3)] + row for (i,row) in enumerate(lst)]

    # Join each row into a line.
    lst = ["".join(row) for row in lst]

    # Join the lines into a single string.
    strng = "\n".join(lst)

    # Now make the header.
    hdr = "".join([c.rjust(3) for c in colkeys])
    hdr = "\n" + " "*3 + hdr + "\n" + "-"*81 + "\n"

    return hdr + strng

def transpose(lstLst):
    """ Computes the 'transpose' of an array - a list of lists.
    """
    return apply(zip,lstLst)

def gcd(a,b):
    try:
        return gcd(b,a%b)
    except:
        return abs(a)