Python: Find index of minimum item in list of floats

python list floating-point minimum floating-point-precision
thornate picture thornate · Nov 9, 2012 · Viewed 97.4k times · Source

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?

Answer

David Wolever picture David Wolever · Nov 9, 2012

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.

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