Is there a foreach function in Python 3

Question

When I meet the situation I can do it in javascript  I always think if there s an foreach function it would be convenience  By foreach I mean the function which is described below   def foreach fn iterable       for x in iterable          fn x    they just do it on every element and didn t yield or return something i think it should be a built-in function and should be more faster than writing it with pure Python  but I didn t found it on the list or it just called another name or I just miss some points here   Maybe I got wrong  cause calling an function in Python cost high  definitely not a good practice for the example  Rather than an out loop  the function should do the loop in side its body looks like this below which already mentioned in many python s code suggestions   def fn  args       for x in args         dosomething   but I thought foreach is still welcome base on the two facts    In normal cases  people just don t care about the performance Sometime the API didn t accept iterable object and you can t rewrite its source

User · Answer

Here is the example of the  quot foreach quot  construction with simultaneous access to the element indexes in Python  for idx  val in enumerate  3  4  5        print  idx  val

User · Answer

Every occurence of  foreach  I ve seen  PHP  C        does basically the same as pythons  for  statement   These are more or less equivalent      PHP  foreach   array as  val        print  val         C  foreach  String val in array        console writeline val         Python for val in array      print val    So  yes  there is a  foreach  in python  It s called  for    What you re describing is an  array map  function  This could be done with list comprehensions in python   names     tom    john    simon    namesCapitalized    capitalize n  for n in names

User · Answer

Yes  although it uses the same syntax as a for loop   for x in   a    b    print x

User · Answer

map can be used for the situation mentioned in the question   E g   map len    abcd   abc    a      4 3 1   For functions that take multiple arguments  more arguments can be given to map   map pow   2  3    4 2     16 9   It returns a list in python 2 x and an iterator in python 3  In case your function takes multiple arguments and the arguments are already in the form of tuples  or any iterable since python 2 6  you can use itertools starmap   which has a very similar syntax to what you were looking for   It returns an iterator   E g    for num in starmap pow    2 3    3 2         print num    gives us 8 and 9

User · Answer

The correct answer is  quot python collections do not have a foreach quot   In native python we need to resort to the external for  element  in  collection  syntax which is not what the OP is after  Python is in general quite weak for functionals programming  There are a few libraries to mitigate a bit  I helped author one of these infixpy https   pypi org project infixpy  from infixpy import Seq  Seq  1 2 3   foreach lambda x  print x    1 2 3  Also see   Left to right application of operations on a list in Python 3

User · Answer

If you re just looking for a more concise syntax you can put the for loop on one line   array     a    b   for value in array  print value    Just separate additional statements with a semicolon   array     a    b   for value in array  print value   print  hello     This may not conform to your local style guide  but it could make sense to do it like this when you re playing around in the console

User · Answer

I think this answers your question  because it is like a  for each  loop  The script below is valid in python  version 3 8    a  1 7 77 7777 77777 777777 7777777 765 456 345 2342 4  if  n    len a    gt  10      print f List is too long   n  elements  expected  lt   10

User · Answer

This does the foreach in python 3  test    0 1 2 3 4 5 6 7 8  test    for fetch in test      print fetch

User · Answer

If I understood you right  you mean that if you have a function  func   you want to check for each item in list if func item  returns true  if you get true for all  then do something   You can use  all    For example  I want to get all prime numbers in range 0-10 in a list   from math import sqrt primes    x for x in range 10  if x  gt  2 and all x   i   0 for i in range 2  int sqrt x     1

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Look at this article  The iterator object nditer from numpy package  introduced in NumPy 1 6  provides many flexible ways to visit all the elements of one or more arrays in a systematic fashion   Example   import random import numpy as np  ptrs   np int32   0  0    400  0    0  400    400  400     for ptr in np nditer ptrs  op flags   readwrite           apply random shift on 1 for each element of the matrix     ptr    random choice  -1  1    print ptrs   d   gt python nditer py    -1   1    399  -1      1 399    399 401

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Other examples   Python Foreach Loop   array     a    b   for value in array      print value        a       b   Python For Loop   array     a    b   for index in range len array        print  index   s   value   s     index  array index          index  0   value  a       index  1   value  b

User · Answer

Python doesn t have a foreach statement per se  It has for loops built into the language   for element in iterable      operate element    If you really wanted to  you could define your own foreach function   def foreach function  iterable       for element in iterable          function element    As a side note the for element in iterable syntax comes from the ABC programming language  one of Python s influences

[python] Is there a 'foreach' function in Python 3?

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