python extract variable from a list-CodePudding

I'm pretty new to python and I'm stacked on a simple problem: i have a list:

mylist = [1, 2, 3, 4]

if I extract one element like this:

print(my_list[1:2])

I get a list of one element, but i cannot compute any calculus by treating it as a variable :

print(my_list[1:2] 1)

because i get the error:

Traceback (most recent call last): File "C:\...\test_tuple.py", line XX, in <module> print(my_list[1:2] 1) TypeError: can only concatenate list (not "int") to list

how do I convert this single element list to a variable?

CodePudding user response：

What you are doing, with :, is slicing. This means grabbing a piece of a list as a new list. What you want is just one index, which you can do be using:

mylist = [1, 2, 3, 4]
print(mylist[2] 1)

You can also turn a one element list into a variable by using:

mylist = [1, 2, 3, 4]
new_list = mylist[1:2]
print(new_list[0] 1)

Lastly you can also use numpy arrays on which you can perform calculations as if it were a normal number as follows:

import numpy as np

mylist = [1, 2, 3, 4]
new_arr = np.array(mylist[1:2])
print(new_arr[0] 1)

of course the first solution is the best in this case, but sometimes other solutions can fit your problem better.

CodePudding user response：

You're error is about, you are adding number to [],

you need to add number to number like below code;

print(my_list[1:2 1])

print(my_list[2 1])

print(my_list[2] 1) ##here youre adding to the value like (my_list[2])3 1 that it will not give you error