The Python Oracle

How to declare and add items to an array in Python?

Become part of the top 3% of the developers by applying to Toptal https://topt.al/25cXVn

--

Music by Eric Matyas
https://www.soundimage.org
Track title: Flying Over Ancient Lands

--

Chapters
00:00 Question
00:30 Accepted answer (Score 832)
01:50 Answer 2 (Score 61)
02:17 Answer 3 (Score 19)
02:45 Answer 4 (Score 16)
03:05 Thank you

--

Full question
https://stackoverflow.com/questions/1048...

--

Content licensed under CC BY-SA
https://meta.stackexchange.com/help/lice...

--

Tags
#python #arrays

#avk47



ACCEPTED ANSWER

Score 856


{} represents an empty dictionary, not an array/list. For lists or arrays, you need [].

To initialize an empty list do this:

my_list = []

or

my_list = list()

To add elements to the list, use append

my_list.append(12)

To extend the list to include the elements from another list use extend

my_list.extend([1,2,3,4])
my_list
--> [12,1,2,3,4]

To remove an element from a list use remove

my_list.remove(2)

Dictionaries represent a collection of key/value pairs also known as an associative array or a map.

To initialize an empty dictionary use {} or dict()

Dictionaries have keys and values

my_dict = {'key':'value', 'another_key' : 0}

To extend a dictionary with the contents of another dictionary you may use the update method

my_dict.update({'third_key' : 1})

To remove a value from a dictionary

del my_dict['key']



ANSWER 2

Score 65


If you do it this way:

array = {}

you are making a dictionary, not an array.

If you need an array (which is called a list in python ) you declare it like this:

array = []

Then you can add items like this:

array.append('a')



ANSWER 3

Score 19


Arrays (called list in python) use the [] notation. {} is for dict (also called hash tables, associated arrays, etc in other languages) so you won't have 'append' for a dict.

If you actually want an array (list), use:

array = []
array.append(valueToBeInserted)



ANSWER 4

Score 3


In some languages like JAVA you define an array using curly braces as following but in python it has a different meaning:

Java:

int[] myIntArray = {1,2,3};
String[] myStringArray = {"a","b","c"};

However, in Python, curly braces are used to define dictionaries, which needs a key:value assignment as {'a':1, 'b':2}

To actually define an array (which is actually called list in python) you can do:

Python:

mylist = [1,2,3]

or other examples like:

mylist = list()
mylist.append(1)
mylist.append(2)
mylist.append(3)
print(mylist)
>>> [1,2,3]