Python: how to find value in list smaller than target

Question

For example I have a non-ordered list of values [10, 20, 50, 200, 100, 300, 250, 150]

I have this code which returns the next greater value:

def GetN         


        

Answer 1

If I understand you correctly, you want the greatest value that is less than your target; e.g. in your example, if your target is 55, you want 50, but if your target is 35, you want 20. The following function should do that:

def get_closest_less(lst, target):
    lst.sort()
    ret_val = None
    previous = lst[0]
    if (previous <= target):
        for ndx in xrange(1, len(lst) - 1):
            if lst[ndx] > target:
                ret_val = previous
                break
            else:
                previous = lst[ndx]
    return str(ret_val)

If you need to step through these values, you could use a generator to get the values in succession:

def next_lesser(l, target):
    for n in l:
        if n < target:
            yield str(n)

Both these worked properly from within a simple program.