Python: Find index of minimum item in list of floats [duplicate]

How can I find the index of the minimum item in a Python list of floats? If they were integers, I would simply do:

minIndex = myList.index(min(myList))

However, with a list of floats I get the following error, I assume because float equality comparison is rather iffy.

ValueError: 0.13417985135 is not in list

Now, I know that I could simply scroll through the list and compare each item to see whether it is < (min + 0.0000000000001) and > (min - 0.0000000000001), but that is kinda messy. Is there a more elegant (preferably built-in) way to find the index of the smallest item in a list of floats?

Solution 1:

I would use:

val, idx = min((val, idx) for (idx, val) in enumerate(my_list))

Then val will be the minimum value and idx will be its index.

Solution 2:

You're effectively scanning the list once to find the min value, then scanning it again to find the index, you can do both in one go:

from operator import itemgetter
min(enumerate(a), key=itemgetter(1))[0] 

Solution 3:

Use of the argmin method for numpy arrays.

import numpy as np
np.argmin(myList)

However, it is not the fastest method: it is 3 times slower than OP's answer on my computer. It may be the most concise one though.