Pandas Equivalent of R's which()

Question

Variations of this question have been asked before, I\'m still having trouble understanding how to actually slice a python series/pandas dataframe based on conditions that

Answer 1

enumerate() returns an iterator that yields an (index, item) tuple in each iteration, so you can't (and don't need to) call .index() again.

Furthermore, your list comprehension syntax is wrong:

indexfuture = [(index, x) for (index, x) in enumerate(df['colname']) if x > yesterday]

Test case:

>>> [(index, x) for (index, x) in enumerate("abcdef") if x > "c"]
[(3, 'd'), (4, 'e'), (5, 'f')]

Of course, you don't need to unpack the tuple:

>>> [tup for tup in enumerate("abcdef") if tup[1] > "c"]
[(3, 'd'), (4, 'e'), (5, 'f')]

unless you're only interested in the indices, in which case you could do something like

>>> [index for (index, x) in enumerate("abcdef") if x > "c"]
[3, 4, 5]