Populating lists in python

Question

I have a loop to populate a list, using a loop format.
I'm supposed to create a list, then - using a loop - populate the list with N elements, and set each list element to its index multiplied by 10.

It is also possible that N will be 0. In this case I'm supposed to output an empty list [], and this what I think is tripping me up.

list = [N]

for x in range(N):
    innerlist = []
    for y in range(N):
        innerlist.append(list)
    list.append(innerlist)
    if N == 0:
        list = []
print (list)

I thought that the if(N==0) statement would reset the value of the list but it doesn't. I should output [] but instead I output [0].

please give an idea of an input and output. also, never call a variable by a class name, e.g. use lst for a variable name, not list. — jpp
– jpp, Commented Feb 3, 2018 at 18:25

cxↄ · Accepted Answer · 2020-03-13 02:15:01Z

7

>>> N = 10
>>> my_list = [iter * 10 for iter in range(N)]
>>> print(my_list)
[0, 10, 20, 30, 40, 50, 60, 70, 80, 90]
>>> N = 0
>>> my_list = [iter * 10 for iter in range(N)]
>>> print(my_list)
[]

edited Mar 13, 2020 at 2:15

cxↄ

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answered Mar 13, 2020 at 1:35

Patrick Atwater

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Comments

thomas.mac · Accepted Answer · 2018-02-03 18:36:31Z

1

lst = range(8)
innerlst = []


for i in lst:
    if 0 in lst:
       innerlst = []
       continue
    else:
       innerlst.append(i*10)

edited Feb 3, 2018 at 18:36

answered Feb 3, 2018 at 18:17

thomas.mac

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Comments

GalAbra · Accepted Answer · 2018-02-04 14:12:06Z

0

If you just add the condition before entering the whole loop, you'll get the expected result:

N = 10
list = []
if (N > 0):
    for i in range(N):
        list.append(i*10)
print(list)
# output: [0, 10, 20, 30, 40, 50, 60, 70, 80, 90]

answered Feb 4, 2018 at 14:12

GalAbra

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Comments

yungmanlungs · Accepted Answer · 2020-01-15 16:11:47Z

0

myList = []

if N == 0:
  print(myList)
else:  
  for i in range(N):
    myList.append(i * 10)
  print(myList)

answered Jan 15, 2020 at 16:11

yungmanlungs

1

2 Comments

ti7 Over a year ago

Welcome to SO! I'm coming from the reviews queue because this was flagged as low-quality. A little explanation also goes a long way with answers. Code-only answers are often outright deleted because they don't explain how they work (which is what will really help OP and incoming readers).. additionally/unfortunately this code snippet also doesn't work.

yungmanlungs Over a year ago

Assuming the OP is also using the same Codio environment, this snippet does in fact work. I will add comments in the future, thanks.

Mr. T · Accepted Answer · 2018-02-04 14:55:33Z

-1

I'm just a beginner myself, but I found this online that matches your question. I have no idea how to format the actual code right, but hopefully this helps!

my_list = []
my_newlist =[]
if N <= 0:
    print(my_list)
else:
    for x in range(N):   
        my_list.append(x)   
        my_newlist= [i* 10 for i in my_list] # not getting the statement 'i * 10 for in i' statement
    print(my_newlist)

[Python] #We provide you with a number N. #Create a list then, using a loop, populate - Pastebin.com. (2017, November 29). Retrieved from https://pastebin.com/2F0zXq6z

edited Feb 4, 2018 at 14:55

Mr. T

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answered Feb 4, 2018 at 13:17

Nicole

1

1 Comment

Mr. T Over a year ago

There is a {} button that formats the code that you selected.

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