I'm trying to get the min value of values in a column of times. If I take a subset of the data I'm able to do it:
TypeError: unorderable types: str() <= float()
It seems to me that you have both floats and strings in that one column.
See if this works:
If it does, then you also have floats in that column. You want to find them and deal with them.
my_floats_indices = [i for i, v in df7['START_TIME'].iteritems() if isinstance(v, float)]
Then look at them with
See if you can fix your problem. Hope that helps.