In this post, we will see how to manage a List in Python.
CREATE
1 2 3 4 5 6 7 8 9 10 | # Empty List lst1 = [] # List lst2 = [ 1 , 2 , 3 , 4 , 5 ] lst3 = [ 1 , 'two' , 3 , 'four' ] print (lst1) print (lst2) print (lst3) |
INSERT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | lst1 = [] lst2 = [ 1 , 2 , 3 , 4 , 5 ] lst4 = [] lst1.append( 100 ) lst1.append( 200 ) lst1.append( 300 ) lst4.append( 100 ) lst4.append( 200 ) lst4.append( 300 ) print ( "lst1: " , lst1) print ( "lst4: " , lst4) lst1.append(lst2) lst4.extend(lst2) print ( "lst1 append lst2: " , lst1) print ( "lst4 extend lst2: " , lst4) |
1 2 3 4 5 6 | list1 = [ 1 , 2 , 3 , 4 ] print (list1) # adding the value 100 at the position 2 => [1,2,100,3,4] list1.insert( 2 , 100 ) print (list1) |
DELETE
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | lst1 = [ 1 , 2 , 3 , 4 , 5 ] lst2 = [ 6 , 7 , 8 , 9 , 10 ] lst3 = [ 3 , 5 , 6 , 7 , 3 ] # remove the object print ( "lst2: " , lst2) lst2.remove( 7 ) print ( "lst2 after remove 7: " ,lst2) # the method remove, delete the first object print ( "lst3: " ,lst3) lst3.remove( 3 ) print ( "lst3 after remove 3: " ,lst3) # remove using the index # index starts from 0 print ( "lst1: " , lst1) del lst1[ 2 ] print ( "lst1 after remove object with index 2: " , lst1) # remove all print ( "lst2: " , lst2) lst2 = [] print ( "lst2: " , lst2) |
1 2 3 4 5 6 7 | list1 = [ 1 , 2 , 3 , 4 ] print (list1) # take the last item in the list and delete it from the list lastItem = list1.pop() print (f "The item is {lastItem}" ) print (list1) |
UPDATE AND SORT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | lst1 = [ 1 , 2 , 3 , 4 , 5 ] lst2 = [ 6 , 2 , 1 , 9 , 7 ] lst3 = [ 3 , 5 , 6 , 7 , 3 ] print ( "lst1: " , lst1) lst1[ 1 ] = 20 lst1[ 4 ] = 50 print ( "lst1 after update: " , lst1) print ( "lst2: " , lst2) / / the sort method modifies the original list lst2.sort() print ( "lst2 sorted: " , lst2) print ( "lst3: " , lst3) / / the sorted method doesn't modify the original list / / but, it will create another list lst4 = sorted (lst3) print ( "lst4: " , lst4) print ( "lst3: " , lst3) |
COPY AND SLICING
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | list1 = [ 1 , 2 , 3 , 4 ] print (f "List1 =>{list1}" ) # COPY list2 = list1.copy() list1.remove( 3 ) print (f "List1 => {list1}" ) print (f "List2=> {list2}" ) # SLICING: => Lst[ Initial : End : IndexJump ] list3 = [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ] # from 1 to 3 print (list3[ 1 : 3 ]) # [2,3] # from 0 to 5 print (list3[ 0 : 5 ]) # [1,2,3,4,5] # all items steps 2 print (list3[:: 2 ]) # [1,3,5,7] # all items steps 2 print (list3[ 1 :: 2 ]) # [2,4,6] # reverse list print (list3[:: - 1 ]) |