[PYTHON] Find the index of items that match the conditions in the pandas data frame / series

Overview

I will introduce how to return the index of the item that matches the condition from the data frame or series of pandas.

Conclusion

df.ix[[df.ix[:,0] == "hoge"],:].index[0]

Commentary

review

df.ix[[df.ix[:,0] == "hoge"],:]

You probably know the syntax, but here I would like to describe how to return a pure index. By the way, the above syntax means "returns the row where column 0 is" hoge "".

Main story

The above result is returned in a pandas dataframe or series (dataframe if you are referencing a dataframe, series if you are referencing a series).

#Data frame
df.ix[[df.ix[:,0] == "hoge"],:] 
#Column with the outermost ix:Since it is specified as multiple columns, the result will be returned in the data frame.

here,

df.ix[[df.ix[:,0] == "hoge"],:].index

If you try, the index of the data frame that matches the condition will be returned as it is. If multiple items meet the conditions, a series with a size larger than 1 will be returned.

Therefore,

df.ix[[df.ix[:,0] == "hoge"],:].index[0]

Then, you can get the index in a format that Python can handle as it is.

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