如何对列表中的每个元素求和？

Question

I have a list:

list = [10, 15,14,20]

And I would like to sum a variable(lets say add=5) to all elements in that list, to have something like:

newlist = [15,20,19,25]

Thanks for your help.

Answer 1

List comprehension:

l = [10, 15, 14, 20]
nl = [i + 5 for i in l]

Map function:

l = [10, 15, 14, 20]
nl = list(map(lambda i: i+5, l))
print(nl)
[15, 20, 19, 25]

Don't use list keyword

>>> list = [10, 15, 14, 20]
>>> list((3, 5, 7))

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-644-e66a8dedf706> in <module>
----> 1 list((3, 5, 7))

TypeError: 'list' object is not callable

You override the function list by a list:

>>> type(list)
type

>>> list = [10, 15, 14, 20]

>>> type(list)
list

Answer 2

Using list comprehension is probably the most pythonic way of doing this.

Like in Corralien's answer (which is very good by the way).

l = [10, 15,14,20]

l = [value+5 for value in l]

This will result in:

l = [15, 20, 19, 25]

In case you don't know how list comprehension works exactly you can break it down into tokens.

The first part value+5 is essentially what is in the for loop and it is what's being appended to the list, and for value in l is just a for loop and goes through each element in list and assigns it to the the variable value

Answer 3

You can use you any type of loop for this.

For example with list comprehension:

list = [10, 15,14,20]
x = 5
new_list = [i+x for i in list]
print(new_list)

Answer 4

First, you shadowed the list function by using it as a variable. You can use a loop.

list1= [10, 15,14,20]
num1=5
new_l=[num+num1 for num in list1]
print(new_l)

Answer 5

if in case you are looking for pandas solution, as you have pandas tag in your question. below solution will help you.

import pandas as pd

alist = [10, 15,14,20]  # initial list
const = 5  # constant you want to add

df= pd.DataFrame(data={"A":alist})  # create a dataframe
df["A"] += const  # add constant to dataframe
print(df)  # print dataframe

Output:

A
0  15
1  20
2  19
3  25