Understanding the map function

0 votes

map(function, iterable, ...)

Apply function to every item of iterable and return a list of the results. If additional iterable arguments are passed, function must take that many arguments and is applied to the items from all iterables in parallel.

If one iterable is shorter than another it is assumed to be extended with None items.

If function is None, the identity function is assumed; if there are multiple arguments, map() returns a list consisting of tuples containing the corresponding items from all iterables (a kind of transpose operation).

The iterable arguments may be a sequence or any iterable object; the result is always a list.

What role does this play in making a Cartesian product?

content = map(tuple, array)

What effect does putting a tuple anywhere in there have? I also noticed that without the map function the output is abc and with it, it's a, b, c.

I want to fully understand this function. The reference definitions is also hard to understand. Too much fancy fluff.

Jul 31, 2018 in Python by bug_seeker
• 15,520 points

1 answer to this question.

0 votes
map isn't particularly pythonic. I would recommend using list comprehensions instead:

map(f, iterable)

is basically equivalent to:

[f(x) for x in iterable]

map on its own can't do a Cartesian product, because the length of its output list is always the same as its input list. You can trivially do a Cartesian product with a list comprehension though:

[(a, b) for a in iterable_a for b in iterable_b]

The syntax is a little confusing -- that's basically equivalent to:

result = []

for a in iterable_a:

  for b in iterable_b:

    result.append((a, b))
answered Jul 31, 2018 by Priyaj
• 58,090 points

Related Questions In Python

0 votes
1 answer

What is the difference between map() and filter() function in python?

The map() function is a type of ...READ MORE

answered Jun 25, 2020 in Python by Sirajul
• 59,230 points
0 votes
1 answer

What is the use of raw_input function in Python?

raw_input fuction is no longer available in ...READ MORE

answered May 2, 2018 in Python by aayushi
• 750 points
+7 votes
8 answers

What exactly is the function of random.seed() in python?

The seed method is used to initialize the ...READ MORE

answered Oct 29, 2018 in Python by Rahul
0 votes
0 answers

what is the purpose of the argument 'end' in the print function?

is it necessary to use this argument ...READ MORE

May 9, 2019 in Python by Waseem
• 4,540 points
0 votes
2 answers
+1 vote
2 answers

how can i count the items in a list?

Syntax :            list. count(value) Code: colors = ['red', 'green', ...READ MORE

answered Jul 7, 2019 in Python by Neha
• 330 points

edited Jul 8, 2019 by Kalgi 4,215 views
0 votes
1 answer
+1 vote
1 answer

What is the function for Factorial in Python

Easiest way: math.factorial(x) (available in 2.6 and ...READ MORE

answered Aug 21, 2018 in Python by Priyaj
• 58,090 points

edited Aug 21, 2018 by Omkar 1,192 views
0 votes
1 answer

Understanding repr( ) function in Python

>>> x = 'foo' >>> x 'foo' So the name x is ...READ MORE

answered Sep 17, 2018 in Python by Priyaj
• 58,090 points
webinar_success Thank you for registering Join Edureka Meetup community for 100+ Free Webinars each month JOIN MEETUP GROUP