Python foreach equivalent [duplicate]

Answer 1

Like this:

for pet in pets :
  print(pet)

In fact, Python only has foreach style for loops.

Answer 2

Sure. A for loop.

for f in pets:
    print f

Answer 3

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.

Answer 4

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.

Answer 5

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 => 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/

Answer 6

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 ##