Trying to get inputs into many arrays - Python

Question

Im trying to write a code in python, that needs to take in user input into 3 lists at the same time. This is my code currently:

N = int(input(""))

x = []     ## x, y, and r are different lists
y = []
r = []

for i in range(N):                     
     x,y,r = input("").split()
     x = int(x)
     y = int(y)
     r = int(r)

print(x)
print(y)
print(r)

My sample input: (You can ignore the <-- x,y,r and the <-- N. I just put that for refrence.)

3 <-- N
1 4 5 <-- x,y,r
2 8 1 < -- x,y,r
6 7 2 < -- x,y,r

Expected Output:

[1, 2, 6]
[4, 8, 7]
[5, 1, 2]

Unfortunately, this is what my output looks like:

6
7
2

NOTE: *I can't find any errors in my code above so any help would be much appreciated! For anyone wondering why the format of taking inputs is very specific, the problem I am trying to solve requires a very strict format which is what I am using. I need to take the "N" input first which will tell me how many times I need to get the input for x,y,r. And yes, I do need to take the values x,y,r at the same time.

First, rename the x,y,r inside the loop, to something other than the names you want to put your data into. Second, don't use '=', use .append() — Boris Lipschitz
– Boris Lipschitz, Commented Mar 21, 2020 at 3:37
It's a little strange that you require the user to enter N but that can only be three. What should happen if the user enters 4? — Mark
– Mark, Commented Mar 21, 2020 at 3:37
@MarkMeyer If the user enters 4 for N it would look like this: [x,y,r] times 4 — Eren145
– Eren145, Commented Mar 21, 2020 at 3:38
@BorisLipschitz Oh i see. I was thinking of doing another way by adding it to the list directly, but that also works. This question can be closed now. — Eren145
– Eren145, Commented Mar 21, 2020 at 3:40
I'll add an "answer" to show what i mean. And yea, i'd rather let user enter as many lines as one wants and finish it up with an empty line or something, but avoid asking the number of entries in advance. Edit: posted. — Boris Lipschitz
– Boris Lipschitz, Commented Mar 21, 2020 at 3:42

Boris Lipschitz · Accepted Answer · 2020-03-21 03:42:59Z

1

Use different variable names for input. Use append, not =. Like this:

N = int(input(""))

x = []     ## x, y, and r are different lists
y = []
r = []

for i in range(N):                     
     tx,ty,tr = input("").split()
     x.append(int(tx))
     y.append(int(ty))
     r.append(int(tr))

print(x)
print(y)
print(r)

answered Mar 21, 2020 at 3:42

Boris Lipschitz

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Comments

alec · Accepted Answer · 2020-03-21 03:48:45Z

1

I'm gonna suggest doing it like this. You are still using tuple assignment for x, y, r just after collecting all the input.

N = int(input(""))

inp = []
for i in range(N):
    inp.append(map(int, input("").split()))

x, y, r = map(list, zip(*inp))
print(x)
print(y)
print(r)

Edit; the one liner approach:

x, y, r = map(list, zip(*[map(int, input("").split()) for i in range(int(input("")))]))

edited Mar 21, 2020 at 3:48

answered Mar 21, 2020 at 3:42

alec

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