Need help with lists

Question

I am struggling with the concept of lists here

Here is my code

m = int(input())
a = [[0,0]]
a *= m
for i in range(m):
a[i][0] = input()
a[i][1] = float(input())
print(a)

But when I input a value every element in the corresponding position of my list gets updated.

For eg: If I enter
3
Alice
23.90

[['Alice', 23.9], ['Alice', 23.9], ['Alice', 23.9]]

whereas I need it to be

[['Alice', 23.9], [0,0], [0,0]] and update the next row accordingly

Answer 1

Problem is a*= m as all sublists have the same id in memory

Answer 2

The pythonic way to create the list, is using a list comprehension. That way the values will be independent from each other. As opposed to the multiplication, in which case the values just pointed to the same spot of memory.

List comprehension:
a = [[0, 0] for x in range(int(input()))]
a[0][0] = 1
print(a)

Then you can write a loop like:
for i in range(len(a)) :

Answer 3

For instance one way is:
m = int(input())
a = []
for i in range(m):
a.append([input(), float(input())])
print(a)

Answer 4

Hi Hubert,

Thanks for your response. Can u suggest a way forward?

Answer 5

Thank you guys