- The imap() function returns an
*"iterator"*that calls a function on the values in the input

iterators and returns the results.

- Like map() but stops when the shortest iterable is exhausted instead

>>>from itertools import * >>> list(imap(pow, xrange(10), count())) [1, 1, 4, 27, 256, 3125, 46656, 823543, 16777216, 387420489]

- pow is a builtin function which caluclates power of two numbers(pow(2,5==>2**5==>32)
- In the above example we passed 3 arguments,1 pow function,xrange(10) ,count.
- imap maps the power function over those other two arguments.This is equivalent to pow(xrange(10),count())
- xrange(10) will exhaust after 10 values,despite count() being infinite iteration it stops because xrange(10) has exhausted.
- we make a list of all the powers by calling list()

#!usr/bin/env/python from itertools import * #Using imap from itertools. print 'Triples:' for i in imap(lambda x:3*x,xrange(5)): print i print "\nMultiples:" for i in imap(lambda x,y:(x, y, x*y), xrange(5), xrange(5,10)): print '%d * %d = %d' % i print "\n Zip" print list(map(pow, xrange(10), count()))Output:

Triples: 0 3 6 9 12 Multiples: 0 * 5 = 0 1 * 6 = 6 2 * 7 = 14 3 * 8 = 24 4 * 9 = 36 Zip Traceback (most recent call last): File "/home/ubuntu/Desktop/map_imap.py", line 11, inThe error is expected because count() is infinite iteration,but xrange() is exhausted so it can't perform operations which have "None" argument.print list(map(pow, xrange(10), count())) TypeError: unsupported operand type(s) for ** or pow(): 'NoneType' and 'int' [Finished in 0.2s with exit code 1]

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