检查列表的所有值是否都小于某个数字（如果未将其设置为该数字）

Question

I have a list in python and I want to make sure that all values in the list are greater than some value. If not then I want to set it to that value.

eg: let us assume the list is

a = [1,2,3,4]

and the value to compare is 3. So I want the list to become

a = [3,3,3,4]

I can do this by iterating through all the elements in the list. Is there a better way to do that?

Answer 1

You can reconstruct the list with a simple conditional expression and list comprehension, like this

a = [1, 2, 3, 4]
print [item if item > 3 else 3 for item in a]
# [3, 3, 3, 4]

For every item in a , it checks if it is greater than 3 , then use item as it is otherwise use 3 .

This is similar but very efficient than the following,

result = []
for item in a:
    if item > 3:
        result.append(item)
    else:
        result.append(3)

But remember that list comprehension creates a new list. So, you have may have to do

a = [item if item > 3 else 3 for item in a]