Python foreach equivalent

Question

I am diving into Python and I have a question about foreach iteration  I am new to Python and I have some experience in C   So I am wondering  if there is some equivalent function in Python for iteration all over all items in my collection  e g    pets     cat    dog    fish   marks     5  4  3  2  1    or something like this

User · Answer

Like this   for pet in pets     print pet    In fact  Python only has foreach style for loops

User · Answer

While the answers above are valid  if you are iterating over a dict  key value  it this is the approach I like to use   for key  value in Dictionary items        print key  value    Therefore  if I wanted to do something like stringify all keys and values in my dictionary  I would do this   stringified dictionary      for key  value in Dictionary items        stringified dictionary update  str key   str value    return stringified dictionary   This avoids any mutation issues when applying this type of iteration  which can cause erratic behavior  sometimes  in my experience

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For a dict we can use a for loop to iterate through the index  key and value    dictionary     a   0   z   25  for index   key  value  in enumerate dictionary items             Code here

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Its also interesting to observe this  To iterate over the indices of a sequence  you can combine range   and len   as follows   a     Mary    had    a    little    lamb   for i in range len a      print i  a i     output   0 Mary 1 had 2 a 3 little 4 lamb   Edit 1  Alternate way     When looping through a sequence  the position index and corresponding value can be retrieved at the same time using the enumerate   function   for i  v in enumerate   tic    tac    toe       print i  v    output  0 tic 1 tac 2 toe

User · Answer

The foreach construct is unfortunately not intrinsic to collections but instead  external to them  The result is two-fold   it can not be chained it requires two lines in idiomatic python   Python does not support a true foreach on collections directly  An example would be myList foreach  a   gt  print a   map  lambda x   x 2   But python does not support it   Partial fixes to this and other missing functionals features in python are provided by various third party libraries including one that I helped author   see https   pypi org project infixpy

User · Answer

Sure  A for loop    for f in pets      print f

User · Answer

For an updated answer you can build a forEach function in Python easily  def forEach list  function       for i  v in enumerate list           function v  i  list   You could also adapt this to map  reduce  filter  and any other array functions from other languages or precedence you d want to bring over  For loops are fast enough  but the boiler plate is longer than forEach or the other functions  You could also extend list to have these functions with a local pointer to a class so you could call them directly on lists as well

User · Answer

This worked for me  def smallest missing positive integer A   A sort   N   len A   now   A 0  for i in range 1  N  1     next   A i        check if there is no gap between 2 numbers and if positive      quot now   1 quot  is the  quot gap quot    if  next  gt  now   1       if now   1  gt  0        return now   1  return the gap   now   next      return max 1  A N-1    1   if there is no positive number returns 1  otherwise the end of A 1

[python] Python foreach equivalent

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