Python Key Skills - List Comprehension
There is an easier way of creating lists in Python called List Comprehensions.
Using only one line of code you will create a list of data that meet certain criteria.
The easiest way of learning about list comprehensions is to write some.
numbersto10 = [number for number in range (10 )]
We start by naming our list.
In the square brackets is the list comprehension.
This one says.
Fill the list with number
Where number is each element of range(10)
Let’s have a look at another one.
foo = 'Hello World!'
bar = [character for character in foo ]
Here we create a list containing all the characters that are in foo.
Type each line of the following code into a Python intepreter.
Try to understand how each list is created by examining the results
List1 = [i for i in range (20 ,10 ,- 1 )]
print (List1 )List2 = [j ** 2 for j in range (10 )]
print (List2 )List3 = [k for k in range (100 ) if k % 2 == 0 ]
print (List3 )List4 = [l .lower () for l in 'ABCDEFG' ]
print (List4 )List5 = ['_' for m in 'Hello World!' ]
print (List5 )List6 = [n for n in 'The Quick Brown Fox' if n .upper () == n and n != ' ' ]
print (List6 )List7 = [word [0 ] for word in 'my race should continue on to the island
shore to help ease boring eye strain tonight '.split ()]
print (List7 )List8 = [[row [i ] for row in [[1 ,2 ,3 ],[4 ,5 ,6 ],[7 ,8 ,9 ]]]for i in range (3 )]
print (List8 )Code It - your own list comprehension
Use list comprehensions to create the following lists.
[-10,-9,-8,-7,-6,-5,-4,-3,-2,-1,0]
A list of all consonants in the sentence ‘The quick brown fox jumped over the lazy dog’
A list of all square numbers formed by squaring the numbers from 1 to 1000.