==================
Perl-Like Examples
==================

This page contains common examples of common perl_-like operations (taken from `Perl One-Liners Explained`_) not covered
in :doc:`sed`.

.. _`perl`: http://www.perl.org/
.. _`Perl One-Liners Explained`: http://www.catonmat.net/series/perl-one-liners-explained

.. figure:: perl-one-liners.jpg 
  :alt: perl
  
  
  
------------
Calculations  
------------

22. Print the sum of all the fields on a line.
    ::
        
        >>> stream_vals('foo.csv', delimit = '\t') | filt(lambda tup: sum(tup)) | to_stream(sys.stdout)

23. Print the sum of all the fields on all lines.
    ::
    
        >>> print stream_vals('foo.csv', delimit = '\t') | filt(lambda tup: sum(tup)) | sum_()    

25. Find the minimum element on a line.
    ::
        
        >>> stream_vals('foo.csv', delimit = '\t') | filt(lambda tup: min(tup)) | to_stream(sys.stdout)

26. Find the minimum element over all the lines.
    ::
    
        >>> print stream_vals('foo.csv', delimit = '\t') | filt(lambda tup: min(tup)) | min_()    

27. Find the maximum element on a line.
    ::
        
        >>> stream_vals('foo.csv', delimit = '\t') | filt(lambda tup: max(tup)) | to_stream(sys.stdout)

28. Find the maximum element over all the lines.
    ::
    
        >>> print stream_vals('foo.csv', delimit = '\t') | filt(lambda tup: max(tup)) | max_()    

29. Replace each field with its absolute value.
    ::
        
        >>> stream_vals('foo.csv', delimit = '\t') | filt(lambda tup: tuple(abs(e) for e in tup)) | to_stream(sys.stdout)

30. Find the total number of fields (words) on each line.
    ::
        
        >>> stream_vals('foo.csv', delimit = '\t') | filt(lambda tup: len(tup)) | to_stream(sys.stdout)

31. Print the total number of fields (words) on each line followed by the line.
    ::
        
        >>> stream_lines('foo.csv') | \
            (csv_split(delimit = '\t') | filt(lambda l: len(l))) + relay() | \
            filt(lambda (len, l): str(len) + '\t' + l) | to_stream(sys.stdout)

32. Find the total number of fields (words) on all lines.
    ::
        
        >>> print stream_vals('foo.csv', delimit = '\t') | filt(lambda tup: len(tup)) | sum_()

33. Print the total number of fields that match a pattern.
    ::
        
        >>> pattern = re.compile(r'foo(.*?)bar')
        >>> print stream_vals('foo.csv', delimit = '\t') | \
            filt(pre = lambda tup: sum((1 if pattern.match(e) else 0 for e in tup) > 0)) | sum_()

34. Print the total number of lines that match a pattern.

        >>> print stream_vals('foo.csv', delimit = '\t') | grep(re.compile(r'foo(.*?)bar') | sum_()