python - Bisect, is it possible to work with descending sorted lists?

Question

How can I use bisect module on lists that are sorted descending? e.g.

import bisect

x = [1.0,2.0,3.0,4.0] # normal, ascending
bisect.insort(x,2.5)  # -->  x is [1.0, 2.0, 2.5, 3.0, 4.0]     ok, works fine for ascending list

# however
x = [1.0,2.0,3.0,4.0]
x.reverse()           # -->  x is [4.0, 3.0, 2.0, 1.0]          descending list
bisect.insort(x,2.5)  # -->  x is [4.0, 3.0, 2.0, 1.0, 2.5]     2.5 at end, not what I want really   

The only methods are insort (insort_right) or insort_left - none of which work for me.

Answer 1

Probably the easiest thing is to borrow the code from the library and make your own version

def reverse_insort(a, x, lo=0, hi=None):
    """Insert item x in list a, and keep it reverse-sorted assuming a
    is reverse-sorted.

    If x is already in a, insert it to the right of the rightmost x.

    Optional args lo (default 0) and hi (default len(a)) bound the
    slice of a to be searched.
    """
    if lo < 0:
        raise ValueError('lo must be non-negative')
    if hi is None:
        hi = len(a)
    while lo < hi:
        mid = (lo+hi)//2
        if x > a[mid]: hi = mid
        else: lo = mid+1
    a.insert(lo, x)