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?
7 Answers
{} 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'] 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') 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) Just for sake of completion, you can also do this:
array = [] array += [valueToBeInserted] If it's a list of strings, this will also work:
array += 'string' 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] You can also do:
array = numpy.append(array, value) Note that the numpy.append() method returns a new object, so if you want to modify your initial array, you have to write: array = ...
I believe you are all wrong. you need to do:
array = array[] in order to define it, and then:
array.append ["hello"] to add to it.
