CODEWITHSUNDEEP
pythonlistprinting
JoshuaESummers
JoshuaESummers

Reputation: 503

Python, how to print specific items from lists in lists?

I am trying to print the first and last item of all the lists inside my list of lists num_list. 

num_list = [[1,2,3],[10,20,30],[100,200,300]]

for x in range(0,3):
    for y in range(0,1) and range(2,3):
        print(num_list[x][y])

But this is just printing 3,30,300 and skipping the 1,10 and 100.

What is a good way to solve this problem?

Upvotes: 1

Views: 43078

Answers (8)

Malo
Malo

Reputation: 1313

Other solution if you want short oneliners:

3 oneliner solutions if printing in one line is good for you:

print(*[num for elem in vec for num in elem[0:3:2]])

print(*[num for elem in vec for num in elem[0:1]+elem[2:3]])

print(*[num for elem in vec for num in elem[0:1]+elem[-1:]])

Output:

1 3 10 30 100 300

or to print one number per line:

print('\n'.join([str(num) for elem in vec for num in elem[0:3:2]]))

1
3
10
30
100
300

Upvotes: 0

dendane djalil
dendane djalil

Reputation: 1

this is an answer based on the original solution but it is not the best one

num_list = [[1,2,3],[10,20,30],[100,200,300]]

for x in range(0, len(num_list)):

    for y in range(0,3,2): #where the change should be
        print(num_list[x][y],end=' ') #display the results in one line

Upvotes: 0

Shivam Jha
Shivam Jha

Reputation: 4572

Probably the smallest solution:

num_list = [[1,2,3],[10,20,30],[100,200,300]]
for x in num_list:
    print(x[0], x[-1])

Upvotes: 1

eshan pandita
eshan pandita

Reputation: 11

num_list = [[1,2,3],[10,20,30],[100,200,300]]

for x in range(0,3):

    for y in range(len(num_list[x])):
        if y==0 or y==2:
            print(num_list[x][y])

you can use above code

Upvotes: 1

abc
abc

Reputation: 11949

You don't need to use range to achieve your task.
Anyway, even if you would like to, there is a mistake in your code in the line

range(0,1) and range(2,3)

By definition and returns the first value which is False, otherwise if there is not, it returns the last value in the expression.
Thus, in your case it only returns range(2,3).

Indeed, 

range(0,1) and range(2,3)

returns

range(2, 3)

since bool(range(0,1)) and bool(range(2,3)) are both evaluated as True.
This is why they are both non-empty sequences. Indeed bool(range(2,2)) would be evaluated as False being empty. For more details see the documentation.

You should rather write something like

import itertools

num_list = [[1,2,3],[10,20,30],[100,200,300]]

for x in range(0,3):
    for y in itertools.chain(range(0,1), range(2,3)):
        print(num_list[x][y])

using itertools.chain.

Upvotes: 1

Vishvajit Pathak
Vishvajit Pathak

Reputation: 3731

num_list = [[1, 2, 3], [10, 20, 30], [100, 200, 300]]

for each in num_list:
    print (each[0], each[-1])

Upvotes: 0

Somesh
Somesh

Reputation: 72

range(0,1) and range(2,3) returns => range(2,3)

Upvotes: 0

Rakesh
Rakesh

Reputation: 82795

Use indexing.

Ex:

num_list = [[1,2,3],[10,20,30],[100,200,300]]

for i in num_list:
    print(i[0], i[-1])   #i[-1] == negative indexing.

Output:

1 3
10 30
100 300

Upvotes: 1

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