How to Create an Array in Python

Arrays are useful and fundamental structures that exist in every high-level language. In Python, arrays are native objects called "lists," and they have a variety of methods associated with each object.

Instructions

1. Create a List With Text or Numeric Elements. You can create a list with a series of text elements in one line in Python.

   List out the text elements you want, separated by commas:
   my_array = ['rebecca', 'juan', 'samir', 'heather']
   You may also use numbers in the array:
   my_array = [-1,0,1,2]
   Or you can mix and match letters and numbers:
   my_array = [1, 'rebecca', 'allard', 15]

2. Access the values of an array by using an index.

   Know that this index is 0 based, meaning that the first element of the array is referenced by using position 0, the second element of the list is referenced by using position 1, and so forth:
   print my_array[2]
>>>> samir

3. Use a list as a dictionary. You can use a dictionary to look up name value pairs for quick retrieval.

   Use a dictionary to look up last names associated with a first name. For example:
   my_dic['rebecca'] = 'allard'
my_dic['juan'] = 'hernandez'
my_dic['heather'] = 'aston'
   You can then use the dictionary to print out the value (the last name) using the key (the first name):
   print my_dic['rebecca']
>>>> allard

4. Nest a list--realize that arrays in Python can contain any data type, including other arrays.

   Create a list that contains another by simply inserting it into the array element list. For example:
   my_friends = ['rebecca', 'ben', 'biella', 'kevin']
my_contacts = ['steve', my_friends, 'lee']
   You can now use my_contacts as a normal array:
   print my_contacts[0]
>>>> steve
   And you can access the nested list by using a second reference:
   print my_contacts[1][2]
>>>> biella

Resources

• Guido Van Rossum's Python tutorial at Python.org