Using filter, map, and reduce in Python

0 votes

My code and functions are wroking fine in Python 2

>>> def f(x):

        return x % 2 != 0 and x % 3 != 0
>>> filter(f, range(2, 25))
[5, 7, 11, 13, 17, 19, 23]

>>> def cube(x):
        return x*x*x
>>> map(cube, range(1, 11))
[1, 8, 27, 64, 125, 216, 343, 512, 729, 1000]

>>> def add(x,y):
        return x+y
>>> reduce(add, range(1, 11))
55

But in Python 3,

I receive the following outputs:

>>> filter(f, range(2, 25))
<filter object at 0x0000000002C14908>
>>> map(cube, range(1, 11))
<map object at 0x0000000002C82B70>
>>> reduce(add, range(1, 11))
Traceback (most recent call last):
  File "<pyshell#8>", line 1, in <module>
    reduce(add, range(1, 11))
NameError: name 'reduce' is not defined

Can anyone help me with this: 

Nov 2, 2018 in Python by findingbugs
• 3,140 points
32 views

1 answer to this question.

Your answer

Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
0 votes

A quick implementation might look like this:

from contextlib import contextmanager    
@contextmanager
def noiters(*funcs):
    if not funcs: 
        funcs = [map, filter, zip] # etc
    from functools import reduce
    globals()[reduce.__name__] = reduce
    for func in funcs:
        globals()[func.__name__] = lambda *ar, func = func, **kwar: list(func(*ar, **kwar))
    try:
        yield
    finally:
        del globals()[reduce.__name__]
        for func in funcs: globals()[func.__name__] = func

With a usage that looks like this:

with noiters(map):
    from operator import add
    print(reduce(add, range(1, 20)))
    print(map(int, ['1', '2']))
answered Nov 2, 2018 by Priyaj
• 56,120 points

Related Questions In Python

0 votes
1 answer

Using Lists and Tuples in Python

if you are familiar with C programming, ...READ MORE

answered May 29, 2018 in Python by Nietzsche's daemon
• 4,260 points
40 views
0 votes
1 answer

Shortest path from source to and from a negative cycle using Bellman Ford in Python

class NegativeWeightFinder: def __init__(self, graph: nx.Graph): ...READ MORE

answered Nov 13, 2018 in Python by Nymeria
• 3,500 points
44 views
0 votes
1 answer

How to filter HTML tags and resolve entities using Python?

Him the answer is a pretty simple ...READ MORE

answered Feb 13 in Python by Nymeria
• 3,500 points
33 views
0 votes
1 answer

how can i count the items in a list?

suppose you have a list a = [0,1,2,3,4,5,6,7,8,9,10] now ...READ MORE

answered May 2 in Python by Mohammad
• 1,400 points
20 views
+4 votes
6 answers
+2 votes
3 answers

How can I play an audio file in the background using Python?

down voteacceptedFor windows: you could use  winsound.SND_ASYNC to play them ...READ MORE

answered Apr 3, 2018 in Python by charlie_brown
• 7,710 points
944 views
+1 vote
1 answer

© 2018 Brain4ce Education Solutions Pvt. Ltd. All rights Reserved.
"PMP®","PMI®", "PMI-ACP®" and "PMBOK®" are registered marks of the Project Management Institute, Inc. MongoDB®, Mongo and the leaf logo are the registered trademarks of MongoDB, Inc.