Bottom Page

Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
 How to create a list with all values being zero
#1
I've written a program that asks the user to input integers which will be placed in a list. I only want to input four integers. I'm looking for ways to make my list all zeros. Doesn't appear that this is as intuitive as arrays are in C++. Anyway this is what I got:

numbers = [0] * 4

index = 0

while index < 4:
    numbers[index] = int(input("Enter a value for the list: "))
    index += 1

print("\nHere is the values you entered: ", end='')

for i in numbers:
    print(str(i) + " ", end='')

print()
print()
According to my book the repetition operator makes multiple copies of a list and then it joins them all together. So is it doing numbers[0] + numbers[0] + numbers[0] + numbers[0] to finally get numbers[0, 0, 0, 0]?

Isn't there an easier way to initialize all elements to zero?
Quote
#2
First, I'm not sure what's so hard about numbers = [0] * 4. That seems like an easy way to initialize a list to zeros. Second of all, you don't need to do that, since you are overwriting all the values anyway. In Python, lists do not have a set size, their size can change. The Pythonic way to get a list of four integers from the user is:

numbers = []
for number in range(4):
    numbers.append(int(input('Enter a value for the list: ')))

print('\nHere are the values you entered: {}.'.format(', '.join(str(number) for number in numbers)))
Craig "Ichabod" O'Brien - xenomind.com
I wish you happiness.
Recommended Tutorials: BBCode, functions, classes, text adventures

Quote
#3
When I tried the numbers [] the program threw an error message. So I presumed you cannot create a list that way.
Quote
#4
numbers = [] is the preferred way in Python,do you get error when run @ichabod801 code?
# Using literals [],the prefered way
>>> numbers = []
>>> numbers
[]
>>> numbers.append(0)
>>> numbers
[0]
>>> numbers.append(99)
>>> numbers
[0, 99]
 
>>> # Function object list()
>>> numbers = list()
>>> numbers
[]

>>> # No need initialize list as may do in other langues as C/C++
>>> numbers = [0] * 4
>>> numbers
[0, 0, 0, 0]
If only shall display numbers in a string i would keep it as string,and only convert to int() if needed.
numbers = []
for number in range(4):
    numbers.append(input('Enter a value for the list: '))

print(f"\nHere are the values you entered: {','.join(numbers)}.")
Output:
λ python num.py Enter a value for the list: 10 Enter a value for the list: 0 Enter a value for the list: 0 Enter a value for the list: 999 Here are the values you entered: 10,0,0,999.
Quote
#5
(Jul-14-2019, 07:20 AM)357mag Wrote: When I tried the numbers [] the program threw an error message. So I presumed you cannot create a list that way.
Instead of whining around what about showing the error your program threw?
numbers []
will definitely throw an error because you need to write
numbers = []
Quote

Top Page

Possibly Related Threads...
Thread Author Replies Views Last Post
  How do I map a list of values to specified colors? larkypython 4 161 Nov-05-2019, 09:22 AM
Last Post: larkypython
  Create a dictionary from a list klllmmm 3 156 Oct-06-2019, 05:50 PM
Last Post: Gribouillis
  Why does this list of lists end up with the same values alehak 2 281 Jul-18-2019, 12:34 PM
Last Post: perfringo
  Remove \n from list of values within a pandas columns klllmmm 2 463 Jun-24-2019, 05:16 AM
Last Post: klllmmm
  Create new list from another list based on condition khalidreemy 1 296 Jun-11-2019, 10:21 AM
Last Post: buran
  update values in list based on dictionary bunti 3 822 Jun-10-2019, 07:26 AM
Last Post: perfringo
  How to create meshgrid with non-integer stepsize of list elements? dazzabaijan 1 346 Mar-11-2019, 02:00 AM
Last Post: ichabod801
  Create a List for Boolean Mask. leoahum 4 669 Oct-09-2018, 02:38 PM
Last Post: leoahum
  create list from repeated pattern in python Code4fun 2 732 Sep-25-2018, 07:09 PM
Last Post: woooee
  Create Alert if string from list appears on other list javalava 1 470 Sep-17-2018, 02:44 PM
Last Post: DeaD_EyE

Forum Jump:


Users browsing this thread: 1 Guest(s)