Python List - array

You should now be able to do some programs that are much more interesting. If you have been keeping up, you should realize that now you can combine all the other things you have learned with if-statements and boolean expressions to make your programs do smart things.

A list is exactly what its name says—a container of things that are organized in order. It’s not complicated; you just have to learn a new syntax. First, there’s how you make a list:

hairs = ['brown', 'blond', 'black']
eyes = ['black', 'brown', 'blue']
weights = [60, 70, 80, 90]

What you do is start the list with the [ (left bracket), which “opens” the list. Then you put each item you want in the list separated by commas, just like when you did function arguments. Lastly, you end the list with a ] (right bracket) to indicate that it’s over. Python then takes this list and all its contents and assigns them to the variable.

Now we will create some exercise with List and see how it works.

Exercise 1:

Let's see output first to understand this.

Output

Let's understand the output step by step

First, we defined 3 Lists.
On line 5, we printed List. When you print List python simply print the entire list starting with [ and ending with ] keeping all element separated with ','.
On line 6, we printed the length of List. It will print how many elements a List has. If you use len() function on a string it will print length of that string. 
On line 7, just like the string index of the List also start from 0. So in our List at place 1 we will have 'blond'. You can also use [0:2] to print multiple elements.

Adding Elements in List:

To add new elements in a List you can use append() function.

The append() will add an element at the end of List. 

Other Functions for List:

  • append - To add new Element at the end.
  • clear - To clear complete List, This will remove all elements from List.
  • count - To count a count duplicate elements in a List. e.g if you have 2 'brown' in your list then list.count('brown') will return 2.
  • extend - This can be used to extend or merg 2 lists. If you wants to merge eyes in hairs then use hairs.extend(eye).
  • index - To find the location of the element. This will return the location of the first find, if you have duplicate elements it will only return a single value.
  • insert - To insert an element at specific location, e.g hairs.insert(1,'red') This ill insert red at 1st position.
  • pop - To remove or pop a specific element. e.g hairs.pop(0) to remove 0th element.
  • remove - To remove an element, in pop you provide index value, but in remove, you provide element value. e.g hairs.remove('red').
  • reverse - To reverse the List
  • sort - To sort the list.

Convert text into List - split

You can convert a text into list using split function.

line1 = "This is some line"

list1 = line1.split()

print(list1) # This will result ['This','is','some','line']

by default split use " " (space) to split and create a list, you can use other keywords also e.g line1.split(','), This will split based on ','.

Exercise:-

Try all functions of List. 

Try passing a string in extend function.

Try more of split function (this is a very useful function while handling data.)

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akarperiwal

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