How to use for cycles in functional programming?

Good evening, I would like to ask the community for help to understand the following,
I have been experimenting with the functional programming method, and I have found basic functions such as map () reduce () filter (), but what I would like to know is what happens with the for cycles within functional programming.

For example, in this code I have to perform many for cycles to find a result:

test = {'one':1,'two':{'two-two':{'two-two-two':222,'three-three-three':333}},'three':3}



for i in test.items():

    if i[0]=="two":

        for s in i[1].items():

            if s[0] == "two-two":

                for a in s[1].items():

                    print(a[1])

Basically I do not know what would apply in this case, it would be a map () or a filter () or something else I hope you can help me

edited Jan 2 at 2:42

AI_Learning

3,86021034

asked Jan 2 at 2:05

Mystic_Force

1748

Related.

– Tomas By
Jan 2 at 2:07

2

Do you mean "loops" when you are saying "cycles"? Because I don't think I've ever heard of "cycles" in this context.

– Blckknght
Jan 2 at 2:50

1

Since this is a dictionary you can select by key, fopr example: test['two']['two-two'].values()

– t.m.adam
Jan 2 at 2:54

Once you've used a for-loop, it is no longer functional programming

– juanpa.arrivillaga
Jan 2 at 16:57

Result means, you want to get 1, 222,333,3 or just 222, 333? In first case recursion is very useful even if there are a higher level nesting.

– hygull
Jan 2 at 17:01

add a comment |

For example, in this code I have to perform many for cycles to find a result:

test = {'one':1,'two':{'two-two':{'two-two-two':222,'three-three-three':333}},'three':3}



for i in test.items():

    if i[0]=="two":

        for s in i[1].items():

            if s[0] == "two-two":

                for a in s[1].items():

                    print(a[1])

Basically I do not know what would apply in this case, it would be a map () or a filter () or something else I hope you can help me

edited Jan 2 at 2:42

AI_Learning

3,86021034

asked Jan 2 at 2:05

Mystic_Force

1748

Related.

– Tomas By
Jan 2 at 2:07

2

Do you mean "loops" when you are saying "cycles"? Because I don't think I've ever heard of "cycles" in this context.

– Blckknght
Jan 2 at 2:50

1

Since this is a dictionary you can select by key, fopr example: test['two']['two-two'].values()

– t.m.adam
Jan 2 at 2:54

Once you've used a for-loop, it is no longer functional programming

– juanpa.arrivillaga
Jan 2 at 16:57

Result means, you want to get 1, 222,333,3 or just 222, 333? In first case recursion is very useful even if there are a higher level nesting.

– hygull
Jan 2 at 17:01

add a comment |

For example, in this code I have to perform many for cycles to find a result:

test = {'one':1,'two':{'two-two':{'two-two-two':222,'three-three-three':333}},'three':3}



for i in test.items():

    if i[0]=="two":

        for s in i[1].items():

            if s[0] == "two-two":

                for a in s[1].items():

                    print(a[1])

Basically I do not know what would apply in this case, it would be a map () or a filter () or something else I hope you can help me

edited Jan 2 at 2:42

AI_Learning

3,86021034

asked Jan 2 at 2:05

Mystic_Force

1748

For example, in this code I have to perform many for cycles to find a result:

test = {'one':1,'two':{'two-two':{'two-two-two':222,'three-three-three':333}},'three':3}



for i in test.items():

    if i[0]=="two":

        for s in i[1].items():

            if s[0] == "two-two":

                for a in s[1].items():

                    print(a[1])

Basically I do not know what would apply in this case, it would be a map () or a filter () or something else I hope you can help me

python python-3.x

edited Jan 2 at 2:42

AI_Learning

3,86021034

asked Jan 2 at 2:05

Mystic_Force

1748

edited Jan 2 at 2:42

AI_Learning

3,86021034

asked Jan 2 at 2:05

Mystic_Force

1748

edited Jan 2 at 2:42

AI_Learning

3,86021034

edited Jan 2 at 2:42

AI_Learning

3,86021034

edited Jan 2 at 2:42

AI_Learning

3,86021034

asked Jan 2 at 2:05

Mystic_Force

1748

asked Jan 2 at 2:05

Mystic_Force

1748

asked Jan 2 at 2:05

Mystic_Force

1748

Related.

– Tomas By
Jan 2 at 2:07

2

Do you mean "loops" when you are saying "cycles"? Because I don't think I've ever heard of "cycles" in this context.

– Blckknght
Jan 2 at 2:50

1

Since this is a dictionary you can select by key, fopr example: test['two']['two-two'].values()

– t.m.adam
Jan 2 at 2:54

Once you've used a for-loop, it is no longer functional programming

– juanpa.arrivillaga
Jan 2 at 16:57

Result means, you want to get 1, 222,333,3 or just 222, 333? In first case recursion is very useful even if there are a higher level nesting.

– hygull
Jan 2 at 17:01

add a comment |

Related.

– Tomas By
Jan 2 at 2:07

2

Do you mean "loops" when you are saying "cycles"? Because I don't think I've ever heard of "cycles" in this context.

– Blckknght
Jan 2 at 2:50

1

Since this is a dictionary you can select by key, fopr example: test['two']['two-two'].values()

– t.m.adam
Jan 2 at 2:54

Once you've used a for-loop, it is no longer functional programming

– juanpa.arrivillaga
Jan 2 at 16:57

Result means, you want to get 1, 222,333,3 or just 222, 333? In first case recursion is very useful even if there are a higher level nesting.

– hygull
Jan 2 at 17:01

Related.

– Tomas By
Jan 2 at 2:07

Do you mean "loops" when you are saying "cycles"? Because I don't think I've ever heard of "cycles" in this context.

– Blckknght
Jan 2 at 2:50

Since this is a dictionary you can select by key, fopr example: test['two']['two-two'].values()

– t.m.adam
Jan 2 at 2:54

Once you've used a for-loop, it is no longer functional programming

– juanpa.arrivillaga
Jan 2 at 16:57

Result means, you want to get 1, 222,333,3 or just 222, 333? In first case recursion is very useful even if there are a higher level nesting.

– hygull
Jan 2 at 17:01

add a comment |

2 Answers
2

active

oldest

votes

I got, here you have used functional programming term to introduce the use of map(), filter() and reduce() in your code but you should not use it here for this scenario as functional programming refers to the implementation of your problem by using functions (modular design).

In your case, you cannot use filter(), reduce() to get the expected result as these functions does not provide you a flexible way to control the program's control.

You can try something like this but I don't want you to use that, you may get None if the condition is not satisfied in case of map(). Using filter() / reduce() does not make sense.

Here, I have tried to make it working as you expect.

>>> def f(tup):

...     items = 

...     if tup[0] == 'two':

...         for s in tup[1].items():

...             if s[0] == "two-two":

...                 for a in s[1].items():

...                     print(a[1])

...                     items.append(a[1])

...         return items

...     else:

...         return None

...

>>> test

{'one': 1, 'two': {'two-two': {'two-two-two': 222, 'three-three-three': 333}},

'three': 3}

>>>

>>> out = list(map(f, test.items()))

222

333

>>> out

[None, [222, 333], None]

>>>

>>> out[1]

[222, 333]

>>>

map(), filter() are bascially used to work on iterables like list, tuple, dictionary, set etc. and produce another iterables by performaing opeartions on items. filter() allows us to filter data (picking even numbers from a list).

reduce() is bascially used to work on iterables and reducing them to a single value (e.g. getting sum of list of numbers).

Initializations

>>> l = [9, 4, 3, 2, 1]

>>> d = {'first': 'Rishikesh', 'last': 'Agrawani'}

>>> t = (3, 4, 5)

>>>

Using map()

>>> # Using map()

...

>>> map_obj = map(lambda n: n ** 2, l)

>>> map_obj

<map object at 0x0000016DAF88B6D8>

>>>

>>> squares = list(map_obj)  # list(map(lambda n: n ** 2, l))

>>> squares

[81, 16, 9, 4, 1]

>>>

>>> details = {k + '-name': v for k, v in d.items()}

>>> details

{'first-name': 'Rishikesh', 'last-name': 'Agrawani'}

>>>

>>> details = dict(map(lambda tup: (tup[0] + '_name', tup[1]), d.items()))

>>> details

{'first_name': 'Rishikesh', 'last_name': 'Agrawani'}

>>>

Using filter()

>>> # Using filter() - let's filter even numbers from list

...

>>> filter_obj = filter(lambda n: n % 2 == 0, l)

>>> filter_obj

<filter object at 0x0000016DAF88B908>

>>>

>>> evens = list(filter_obj)

>>> evens

[4, 2]

>>>

Using reduce()

>>> # Using reduce() - finding sum of al numbers in a list

... # i.e. reducing list of values to a single value

...

>>> from functools import reduce

>>>

>>> total = reduce(lambda n1, n2: n1 + n2, l)

>>> total

19

>>>

edited Jan 15 at 2:06

answered Jan 2 at 18:54

hygull

3,71021432

add a comment |

-3

You can use a forEach() function to apply some callback function to each item in a collection

A basic implementation would look like this:

   function forEach(callback) {

      for(index=0;index<len_of_collection;index++) {

         callback(collection[index], index, collection);

      }

   }

You would need to make sure your collection implements this method for you to be able to call it from the collection like so:

some_collection.forEach(myCustomCallback)

Or inline:

some_collection.forEach(item => console.log(item))

Please excuse the JavaScript, I know the question was in Python but the concept is not language specific.

EDIT: https://www.geeksforgeeks.org/python-map-function/

map() function returns a list of the results after applying the given
function to each item of a given iterable (list, tuple etc.)

Your example does not show modification. Therefore, map symantically would not be correct. If what you want is to apply some function without modification, explore options similar to forEach.

edited Jan 2 at 16:49

answered Jan 2 at 2:24

Francisco Garcia

704

1

This seems to be more or less what the builtin map function already does. You don't need to reinvent the wheel to do it in Python.

– Blckknght
Jan 2 at 5:07

Map modifies each entry in a collection. If you only want to apply some logic to each element without modifiying the existing collection, you would use a forEach. Unless it works differently in python, thats usually the definition of a map function.

– Francisco Garcia
Jan 2 at 16:39

The question is related to Python's map(), filter() and reduce(). Your code is related to JavaScript's map(), filter() and reduce().

– hygull
Jan 2 at 16:55

@FranciscoGarcia absolutely incorrect, collections are not modified in-place by map. And anyway, forEach is not functional either, and map is eminently functional.

– juanpa.arrivillaga
Jan 2 at 16:57

Python's map() only modifies its input if the given function is actually a method that modifies its object (e.g. reverse on a list).

– nekomatic
Jan 2 at 16:59

|
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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

In your case, you cannot use filter(), reduce() to get the expected result as these functions does not provide you a flexible way to control the program's control.

You can try something like this but I don't want you to use that, you may get None if the condition is not satisfied in case of map(). Using filter() / reduce() does not make sense.

Here, I have tried to make it working as you expect.

>>> def f(tup):

...     items = 

...     if tup[0] == 'two':

...         for s in tup[1].items():

...             if s[0] == "two-two":

...                 for a in s[1].items():

...                     print(a[1])

...                     items.append(a[1])

...         return items

...     else:

...         return None

...

>>> test

{'one': 1, 'two': {'two-two': {'two-two-two': 222, 'three-three-three': 333}},

'three': 3}

>>>

>>> out = list(map(f, test.items()))

222

333

>>> out

[None, [222, 333], None]

>>>

>>> out[1]

[222, 333]

>>>

reduce() is bascially used to work on iterables and reducing them to a single value (e.g. getting sum of list of numbers).

Initializations

>>> l = [9, 4, 3, 2, 1]

>>> d = {'first': 'Rishikesh', 'last': 'Agrawani'}

>>> t = (3, 4, 5)

>>>

Using map()

>>> # Using map()

...

>>> map_obj = map(lambda n: n ** 2, l)

>>> map_obj

<map object at 0x0000016DAF88B6D8>

>>>

>>> squares = list(map_obj)  # list(map(lambda n: n ** 2, l))

>>> squares

[81, 16, 9, 4, 1]

>>>

>>> details = {k + '-name': v for k, v in d.items()}

>>> details

{'first-name': 'Rishikesh', 'last-name': 'Agrawani'}

>>>

>>> details = dict(map(lambda tup: (tup[0] + '_name', tup[1]), d.items()))

>>> details

{'first_name': 'Rishikesh', 'last_name': 'Agrawani'}

>>>

Using filter()

>>> # Using filter() - let's filter even numbers from list

...

>>> filter_obj = filter(lambda n: n % 2 == 0, l)

>>> filter_obj

<filter object at 0x0000016DAF88B908>

>>>

>>> evens = list(filter_obj)

>>> evens

[4, 2]

>>>

Using reduce()

>>> # Using reduce() - finding sum of al numbers in a list

... # i.e. reducing list of values to a single value

...

>>> from functools import reduce

>>>

>>> total = reduce(lambda n1, n2: n1 + n2, l)

>>> total

19

>>>

edited Jan 15 at 2:06

answered Jan 2 at 18:54

hygull

3,71021432

add a comment |

In your case, you cannot use filter(), reduce() to get the expected result as these functions does not provide you a flexible way to control the program's control.

You can try something like this but I don't want you to use that, you may get None if the condition is not satisfied in case of map(). Using filter() / reduce() does not make sense.

Here, I have tried to make it working as you expect.

>>> def f(tup):

...     items = 

...     if tup[0] == 'two':

...         for s in tup[1].items():

...             if s[0] == "two-two":

...                 for a in s[1].items():

...                     print(a[1])

...                     items.append(a[1])

...         return items

...     else:

...         return None

...

>>> test

{'one': 1, 'two': {'two-two': {'two-two-two': 222, 'three-three-three': 333}},

'three': 3}

>>>

>>> out = list(map(f, test.items()))

222

333

>>> out

[None, [222, 333], None]

>>>

>>> out[1]

[222, 333]

>>>

reduce() is bascially used to work on iterables and reducing them to a single value (e.g. getting sum of list of numbers).

Initializations

>>> l = [9, 4, 3, 2, 1]

>>> d = {'first': 'Rishikesh', 'last': 'Agrawani'}

>>> t = (3, 4, 5)

>>>

Using map()

>>> # Using map()

...

>>> map_obj = map(lambda n: n ** 2, l)

>>> map_obj

<map object at 0x0000016DAF88B6D8>

>>>

>>> squares = list(map_obj)  # list(map(lambda n: n ** 2, l))

>>> squares

[81, 16, 9, 4, 1]

>>>

>>> details = {k + '-name': v for k, v in d.items()}

>>> details

{'first-name': 'Rishikesh', 'last-name': 'Agrawani'}

>>>

>>> details = dict(map(lambda tup: (tup[0] + '_name', tup[1]), d.items()))

>>> details

{'first_name': 'Rishikesh', 'last_name': 'Agrawani'}

>>>

Using filter()

>>> # Using filter() - let's filter even numbers from list

...

>>> filter_obj = filter(lambda n: n % 2 == 0, l)

>>> filter_obj

<filter object at 0x0000016DAF88B908>

>>>

>>> evens = list(filter_obj)

>>> evens

[4, 2]

>>>

Using reduce()

>>> # Using reduce() - finding sum of al numbers in a list

... # i.e. reducing list of values to a single value

...

>>> from functools import reduce

>>>

>>> total = reduce(lambda n1, n2: n1 + n2, l)

>>> total

19

>>>

edited Jan 15 at 2:06

answered Jan 2 at 18:54

hygull

3,71021432

add a comment |

In your case, you cannot use filter(), reduce() to get the expected result as these functions does not provide you a flexible way to control the program's control.

You can try something like this but I don't want you to use that, you may get None if the condition is not satisfied in case of map(). Using filter() / reduce() does not make sense.

Here, I have tried to make it working as you expect.

>>> def f(tup):

...     items = 

...     if tup[0] == 'two':

...         for s in tup[1].items():

...             if s[0] == "two-two":

...                 for a in s[1].items():

...                     print(a[1])

...                     items.append(a[1])

...         return items

...     else:

...         return None

...

>>> test

{'one': 1, 'two': {'two-two': {'two-two-two': 222, 'three-three-three': 333}},

'three': 3}

>>>

>>> out = list(map(f, test.items()))

222

333

>>> out

[None, [222, 333], None]

>>>

>>> out[1]

[222, 333]

>>>

reduce() is bascially used to work on iterables and reducing them to a single value (e.g. getting sum of list of numbers).

Initializations

>>> l = [9, 4, 3, 2, 1]

>>> d = {'first': 'Rishikesh', 'last': 'Agrawani'}

>>> t = (3, 4, 5)

>>>

Using map()

>>> # Using map()

...

>>> map_obj = map(lambda n: n ** 2, l)

>>> map_obj

<map object at 0x0000016DAF88B6D8>

>>>

>>> squares = list(map_obj)  # list(map(lambda n: n ** 2, l))

>>> squares

[81, 16, 9, 4, 1]

>>>

>>> details = {k + '-name': v for k, v in d.items()}

>>> details

{'first-name': 'Rishikesh', 'last-name': 'Agrawani'}

>>>

>>> details = dict(map(lambda tup: (tup[0] + '_name', tup[1]), d.items()))

>>> details

{'first_name': 'Rishikesh', 'last_name': 'Agrawani'}

>>>

Using filter()

>>> # Using filter() - let's filter even numbers from list

...

>>> filter_obj = filter(lambda n: n % 2 == 0, l)

>>> filter_obj

<filter object at 0x0000016DAF88B908>

>>>

>>> evens = list(filter_obj)

>>> evens

[4, 2]

>>>

Using reduce()

>>> # Using reduce() - finding sum of al numbers in a list

... # i.e. reducing list of values to a single value

...

>>> from functools import reduce

>>>

>>> total = reduce(lambda n1, n2: n1 + n2, l)

>>> total

19

>>>

edited Jan 15 at 2:06

answered Jan 2 at 18:54

hygull

3,71021432

In your case, you cannot use filter(), reduce() to get the expected result as these functions does not provide you a flexible way to control the program's control.

You can try something like this but I don't want you to use that, you may get None if the condition is not satisfied in case of map(). Using filter() / reduce() does not make sense.

Here, I have tried to make it working as you expect.

>>> def f(tup):

...     items = 

...     if tup[0] == 'two':

...         for s in tup[1].items():

...             if s[0] == "two-two":

...                 for a in s[1].items():

...                     print(a[1])

...                     items.append(a[1])

...         return items

...     else:

...         return None

...

>>> test

{'one': 1, 'two': {'two-two': {'two-two-two': 222, 'three-three-three': 333}},

'three': 3}

>>>

>>> out = list(map(f, test.items()))

222

333

>>> out

[None, [222, 333], None]

>>>

>>> out[1]

[222, 333]

>>>

reduce() is bascially used to work on iterables and reducing them to a single value (e.g. getting sum of list of numbers).

Initializations

>>> l = [9, 4, 3, 2, 1]

>>> d = {'first': 'Rishikesh', 'last': 'Agrawani'}

>>> t = (3, 4, 5)

>>>

Using map()

>>> # Using map()

...

>>> map_obj = map(lambda n: n ** 2, l)

>>> map_obj

<map object at 0x0000016DAF88B6D8>

>>>

>>> squares = list(map_obj)  # list(map(lambda n: n ** 2, l))

>>> squares

[81, 16, 9, 4, 1]

>>>

>>> details = {k + '-name': v for k, v in d.items()}

>>> details

{'first-name': 'Rishikesh', 'last-name': 'Agrawani'}

>>>

>>> details = dict(map(lambda tup: (tup[0] + '_name', tup[1]), d.items()))

>>> details

{'first_name': 'Rishikesh', 'last_name': 'Agrawani'}

>>>

Using filter()

>>> # Using filter() - let's filter even numbers from list

...

>>> filter_obj = filter(lambda n: n % 2 == 0, l)

>>> filter_obj

<filter object at 0x0000016DAF88B908>

>>>

>>> evens = list(filter_obj)

>>> evens

[4, 2]

>>>

Using reduce()

>>> # Using reduce() - finding sum of al numbers in a list

... # i.e. reducing list of values to a single value

...

>>> from functools import reduce

>>>

>>> total = reduce(lambda n1, n2: n1 + n2, l)

>>> total

19

>>>

edited Jan 15 at 2:06

answered Jan 2 at 18:54

hygull

3,71021432

edited Jan 15 at 2:06

answered Jan 2 at 18:54

hygull

3,71021432

answered Jan 2 at 18:54

hygull

3,71021432

answered Jan 2 at 18:54

hygull

3,71021432

add a comment |

-3

You can use a forEach() function to apply some callback function to each item in a collection

A basic implementation would look like this:

   function forEach(callback) {

      for(index=0;index<len_of_collection;index++) {

         callback(collection[index], index, collection);

      }

   }

You would need to make sure your collection implements this method for you to be able to call it from the collection like so:

some_collection.forEach(myCustomCallback)

Or inline:

some_collection.forEach(item => console.log(item))

Please excuse the JavaScript, I know the question was in Python but the concept is not language specific.

EDIT: https://www.geeksforgeeks.org/python-map-function/

map() function returns a list of the results after applying the given
function to each item of a given iterable (list, tuple etc.)

Your example does not show modification. Therefore, map symantically would not be correct. If what you want is to apply some function without modification, explore options similar to forEach.

edited Jan 2 at 16:49

answered Jan 2 at 2:24

Francisco Garcia

704

1

This seems to be more or less what the builtin map function already does. You don't need to reinvent the wheel to do it in Python.

– Blckknght
Jan 2 at 5:07

Map modifies each entry in a collection. If you only want to apply some logic to each element without modifiying the existing collection, you would use a forEach. Unless it works differently in python, thats usually the definition of a map function.

– Francisco Garcia
Jan 2 at 16:39

The question is related to Python's map(), filter() and reduce(). Your code is related to JavaScript's map(), filter() and reduce().

– hygull
Jan 2 at 16:55

@FranciscoGarcia absolutely incorrect, collections are not modified in-place by map. And anyway, forEach is not functional either, and map is eminently functional.

– juanpa.arrivillaga
Jan 2 at 16:57

Python's map() only modifies its input if the given function is actually a method that modifies its object (e.g. reverse on a list).

– nekomatic
Jan 2 at 16:59

|
show 2 more comments

-3

You can use a forEach() function to apply some callback function to each item in a collection

A basic implementation would look like this:

   function forEach(callback) {

      for(index=0;index<len_of_collection;index++) {

         callback(collection[index], index, collection);

      }

   }

You would need to make sure your collection implements this method for you to be able to call it from the collection like so:

some_collection.forEach(myCustomCallback)

Or inline:

some_collection.forEach(item => console.log(item))

Please excuse the JavaScript, I know the question was in Python but the concept is not language specific.

EDIT: https://www.geeksforgeeks.org/python-map-function/

map() function returns a list of the results after applying the given
function to each item of a given iterable (list, tuple etc.)

Your example does not show modification. Therefore, map symantically would not be correct. If what you want is to apply some function without modification, explore options similar to forEach.

edited Jan 2 at 16:49

answered Jan 2 at 2:24

Francisco Garcia

704

1

This seems to be more or less what the builtin map function already does. You don't need to reinvent the wheel to do it in Python.

– Blckknght
Jan 2 at 5:07

Map modifies each entry in a collection. If you only want to apply some logic to each element without modifiying the existing collection, you would use a forEach. Unless it works differently in python, thats usually the definition of a map function.

– Francisco Garcia
Jan 2 at 16:39

The question is related to Python's map(), filter() and reduce(). Your code is related to JavaScript's map(), filter() and reduce().

– hygull
Jan 2 at 16:55

@FranciscoGarcia absolutely incorrect, collections are not modified in-place by map. And anyway, forEach is not functional either, and map is eminently functional.

– juanpa.arrivillaga
Jan 2 at 16:57

Python's map() only modifies its input if the given function is actually a method that modifies its object (e.g. reverse on a list).

– nekomatic
Jan 2 at 16:59

|
show 2 more comments

-3

You can use a forEach() function to apply some callback function to each item in a collection

A basic implementation would look like this:

   function forEach(callback) {

      for(index=0;index<len_of_collection;index++) {

         callback(collection[index], index, collection);

      }

   }

You would need to make sure your collection implements this method for you to be able to call it from the collection like so:

some_collection.forEach(myCustomCallback)

Or inline:

some_collection.forEach(item => console.log(item))

Please excuse the JavaScript, I know the question was in Python but the concept is not language specific.

EDIT: https://www.geeksforgeeks.org/python-map-function/

map() function returns a list of the results after applying the given
function to each item of a given iterable (list, tuple etc.)

Your example does not show modification. Therefore, map symantically would not be correct. If what you want is to apply some function without modification, explore options similar to forEach.

edited Jan 2 at 16:49

answered Jan 2 at 2:24

Francisco Garcia

704

You can use a forEach() function to apply some callback function to each item in a collection

A basic implementation would look like this:

   function forEach(callback) {

      for(index=0;index<len_of_collection;index++) {

         callback(collection[index], index, collection);

      }

   }

You would need to make sure your collection implements this method for you to be able to call it from the collection like so:

some_collection.forEach(myCustomCallback)

Or inline:

some_collection.forEach(item => console.log(item))

Please excuse the JavaScript, I know the question was in Python but the concept is not language specific.

EDIT: https://www.geeksforgeeks.org/python-map-function/

map() function returns a list of the results after applying the given
function to each item of a given iterable (list, tuple etc.)

Your example does not show modification. Therefore, map symantically would not be correct. If what you want is to apply some function without modification, explore options similar to forEach.

edited Jan 2 at 16:49

answered Jan 2 at 2:24

Francisco Garcia

704

edited Jan 2 at 16:49

answered Jan 2 at 2:24

Francisco Garcia

704

answered Jan 2 at 2:24

Francisco Garcia

704

answered Jan 2 at 2:24

Francisco Garcia

704

1

This seems to be more or less what the builtin map function already does. You don't need to reinvent the wheel to do it in Python.

– Blckknght
Jan 2 at 5:07

Map modifies each entry in a collection. If you only want to apply some logic to each element without modifiying the existing collection, you would use a forEach. Unless it works differently in python, thats usually the definition of a map function.

– Francisco Garcia
Jan 2 at 16:39

The question is related to Python's map(), filter() and reduce(). Your code is related to JavaScript's map(), filter() and reduce().

– hygull
Jan 2 at 16:55

@FranciscoGarcia absolutely incorrect, collections are not modified in-place by map. And anyway, forEach is not functional either, and map is eminently functional.

– juanpa.arrivillaga
Jan 2 at 16:57

Python's map() only modifies its input if the given function is actually a method that modifies its object (e.g. reverse on a list).

– nekomatic
Jan 2 at 16:59

|
show 2 more comments

1

This seems to be more or less what the builtin map function already does. You don't need to reinvent the wheel to do it in Python.

– Blckknght
Jan 2 at 5:07

Map modifies each entry in a collection. If you only want to apply some logic to each element without modifiying the existing collection, you would use a forEach. Unless it works differently in python, thats usually the definition of a map function.

– Francisco Garcia
Jan 2 at 16:39

The question is related to Python's map(), filter() and reduce(). Your code is related to JavaScript's map(), filter() and reduce().

– hygull
Jan 2 at 16:55

@FranciscoGarcia absolutely incorrect, collections are not modified in-place by map. And anyway, forEach is not functional either, and map is eminently functional.

– juanpa.arrivillaga
Jan 2 at 16:57

Python's map() only modifies its input if the given function is actually a method that modifies its object (e.g. reverse on a list).

– nekomatic
Jan 2 at 16:59

This seems to be more or less what the builtin map function already does. You don't need to reinvent the wheel to do it in Python.

– Blckknght
Jan 2 at 5:07

Map modifies each entry in a collection. If you only want to apply some logic to each element without modifiying the existing collection, you would use a forEach. Unless it works differently in python, thats usually the definition of a map function.

– Francisco Garcia
Jan 2 at 16:39

The question is related to Python's map(), filter() and reduce(). Your code is related to JavaScript's map(), filter() and reduce().

– hygull
Jan 2 at 16:55

@FranciscoGarcia absolutely incorrect, collections are not modified in-place by map. And anyway, forEach is not functional either, and map is eminently functional.

– juanpa.arrivillaga
Jan 2 at 16:57

Python's map() only modifies its input if the given function is actually a method that modifies its object (e.g. reverse on a list).

– nekomatic
Jan 2 at 16:59

|
show 2 more comments

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