sort | uniq -c | sort -rn in Python

#!/usr/bin/env python
# sort | uniq -c | sort -rn in Python
# Released into the public domain.  No rights reserved.

import sys

# Build a dictionary of lines and their associated counts.
counts = {}
#input_file = open("/path/to/file", "r")
input_file = sys.stdin
try:
    for line in input_file:
        line = line.rstrip("\n").rstrip("\r")        # Strip trailing LF/CRLF
        counts[line] = counts.get(line, 0) + 1
finally:
    if input_file is not sys.stdin:
        input_file.close()

# Build a list of [(lineA, countA), (lineB, countB), ... ]
sorted_counts = list(counts.items())

# Sort the list by (count, line) in reverse order.
sorted_counts.sort(lambda a,b: -cmp((a[1], a[0]), (b[1], b[0])))

# Output the lines
for line, count in sorted_counts:
    print "%7d %s" % (count, line)