How to check if a value is in between values in a list? (Python)-CodePudding

I want to check if a value exists in between two numbers in a sorted list and print what two numbers it exists between. For example, if the list is [1, 4, 8, 12, 16, 20] and I want to see what two numbers the number 3 is between, 1 and 4 should be printed out. Is there any way to do this in python preferably without importing a module?

CodePudding user response：

If the list is sorted, you could use bisect.bisect:

import bisect

lst = [1, 4, 8, 12, 16, 20]

i = bisect.bisect(lst, 3)
print(lst[i - 1], lst[i])

Output

1 4

UPDATE

Without importing a module use:

lst = [1, 4, 8, 12, 16, 20]
i = next(j for j, e in enumerate(lst) if e >= 3)
print(lst[i - 1], lst[i])

Output

1 4

Note that the time complexity of the second approach is O(n) vs O(logn) of bisect. As an alternative you could implement bisect, in the end is just binary search.

CodePudding user response：

I am not sure if there is a inbuilt function for this but you can check it very easily by iterating over the list and take a variable as input which you want to compare. If list is not sorted in that case may be you can sort the list first.

CodePudding user response：

I was going to suggest using range()

You can have list like so:

list = [1, 4, 5, 15, 22]
is_in_range = 3 in range(list[0], list[1]) # or any other element of the list - you can even iterate over this
print(is_in_range)

Not the best solution but works.