Get row index from DataFrame row

Question

Is it possible to get the row number (i.e. "the ordinal position of the index value") of a DataFrame row without adding an extra row that contains the row number (the index can be arbitrary, i.e. even a MultiIndex)?

>>> import pandas as pd
>>> df = pd.DataFrame({'a': [2, 3, 4, 2, 4, 6]})
>>> result = df[df.a > 3]
>>> result.iloc[0]
a    4
Name: 2, dtype: int64
# but how can I get the original row index of iloc[0] in df?

I could have done df['row_index'] = range(len(df)) which would maintain the original row number, but I am wondering if Pandas has a built-in way of doing this.

EdChum · Accepted Answer · 2016-02-06 07:40:34Z

27

Access the .name attribute and use get_loc:

In [10]:
df.index.get_loc(result.iloc[0].name)

Out[10]:
2

edited Feb 6, 2016 at 7:40

answered Feb 6, 2016 at 7:15

EdChum

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6 Comments

orange Over a year ago

Unfortunately, this refers to the original index. Try: df = pd.DataFrame({'a': [2, 3, 4, 2, 4, 6]}, index=[4, 3, 7, 1, 5, 9]);result = df[df.a > 3];result.iloc[0].name which returns 7.

EdChum Over a year ago

sorry what are you after exactly? the ordinal position of the index value?

orange Over a year ago

Yes, sorry "row number" may have been misleading.

orange Over a year ago

Thanks for the edit. I think it should to be df.index.get_loc(result.index[0]) if I'm not mistaken...

EdChum Over a year ago

result.index[0] is the same as result.iloc[0].name the difference here is that you're explicitly accessing the first index element, whilst the latter is accessing the first element's index value

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jarh1992 · Accepted Answer · 2022-03-30 02:39:45Z

0

Looking this from a different side:

for r in df.itertuples():
    getattr(r, 'Index')

Where df is the data frame. May be you want to use a conditional to get the index when a condition are met.

answered Mar 30, 2022 at 2:39

jarh1992

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