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

I'm trying to add items to an array in python.

I run

array = {}


Then, I try to add something to this array by doing:

array.append(valueToBeInserted)


There doesn't seem to be a .append method for this. How do I add items to an array?

.append

4 Answers
4

{} 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

append

my_list.append(12)


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

extend

extend

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


To remove an element from a list use remove

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()

{}

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

update

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


To remove a value from a dictionary

del my_dict['key']


No, if you do:

array = {}


IN your example you are using array as a dictionary, not an array. If you need an array, in Python you use lists:

array

array =


Then, to add items you do:

array.append('a')


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.

list

{}

dict

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

array =
array.append(valueToBeInserted)


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}

key:value

{'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]


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