Getting the index of a timestamp element in a pandas data frame

Question

I have a pandas data frame that I created as follows:

dates = pd.date_range('12-01-2020','12-10-2020')
my_df = pd.DataFrame(dates, columns = ['Date'])

So this gives

        Date
0 2020-12-01
1 2020-12-02
2 2020-12-03
3 2020-12-04
4 2020-12-05
5 2020-12-06
6 2020-12-07
7 2020-12-08
8 2020-12-09
9 2020-12-10

My question is very elementary: What is the correct function to use for returning the index of a given date? I have tried my_df['Date'].index('2020-12-05'), expecting to get 4, but instead I got the following error: 'RangeIndex' object is not callable. I also tried

d = pd.TimeStamp('12-05-2020' + '00:00:00') 
my_df['Date'].index(d)

but I got the same error...I'm confused because I've used .index successfully in similar situations, such as on lists with integers. Any help would be appreciated.

Kay · Accepted Answer · 2020-12-05 20:54:24Z

1

You can also use query without having to reset the index

my_df.query("Date == '2020-12-05'").index.values[0]

or if you want to assign the value to search:

d = pd.to_datetime('12-05-2020') 
my_df.query("Date == @d").index.values[0]

or without loc or query

my_df[my_df.Date == '12-05-2020'].index.values[0]

And your answer:

edited Dec 5, 2020 at 20:54

answered Dec 5, 2020 at 20:46

Kay

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4 Comments

Leonidas Over a year ago

Thanks, this works. But is there an alternate way that uses .index or .loc, but that doesn't involve resetting the index?

Kay Over a year ago

My answer doesn't reset the index

Leonidas Over a year ago

Thanks, I like the third option the best :) It seems to me a more natural way of getting the index.

sammywemmy Over a year ago

I do not think you need the .values, you can index directly into the index

Jamie · Accepted Answer · 2020-12-05 20:38:30Z

0

You could reset the index

my_df.reset_index().loc[my_df.Date == '2020-12-05', 'index']

or to get the scalar

my_df.reset_index().loc[my_df.Date == '2020-12-05', 'index'].values[0]

answered Dec 5, 2020 at 20:38

Jamie

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1 Comment

Leonidas Over a year ago

This seems very cumbersome...there must be an easier way that doesn't require reset_index...

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