Quickly Find the Index in an Array Closest to Some Value

Question

I have an array of values, t, that is always in increasing order (but not always uniformly spaced). I have another single value, x. I need to find the index in t such that

Answer 1

Use searchsorted:

t = np.arange(10,100000)         # Not always uniform, but in increasing order
x = np.random.uniform(10,100000)

print t.searchsorted(x)

Edit:

Ah yes, I see that's what you do in f1. Maybe f3 below is easier to read than f1.

def f3(t, x):
    ind = t.searchsorted(x)
    if ind == len(t):
        return ind - 1 # x > max(t)
    elif ind == 0:
        return 0
    before = ind-1
    if x-t[before] < t[ind]-x:
        ind -= 1
    return ind