CODEWITHSUNDEEP
pythonpython-2.7pandas
vks
vks

Reputation: 67998

Pandas Get a list of index from dataframe.loc

I have looked through various sites and SO posts.Seems easy but somehow i am stuck with this.I am using

print frame.loc[(frame['RR'].str.contains("^[^123]", na=False)), 'RR'].isin(series1.str.slice(1))

to get

3     True
4    False
8    False
Name: RR, dtype: bool

Now,somehow i want the indexes only so that i can use that in dataframe.drop. Basically all the indexes where value is True , i have to grab indexes and drop them.Is there any other way as well without using indexes?

Upvotes: 2

Views: 1062

Answers (1)

user2285236
user2285236

Reputation:

You are testing two conditions on the same column so these can be combined (and negated):

frame[~((frame['RR'].str.contains("^[^123]", na=False)) & (frame['RR'].isin(series1.str.slice(1))))]

Here, after ~ operator, it checks whether a particular row satisfies both conditions - same as the boolean array you get in the end. With ~, you turn True's to False's and False's to True's. Finally, frame[condition] returns the rows that satisfy the final condition with boolean indexing.

In a more readable format:

condition1 = frame['RR'].str.contains("^[^123]", na=False)
condition2 = frame['RR'].isin(series1.str.slice(1))
frame[~(condition1 & condition2)]

As an alternative (requires 0.18.0), you can get the indices of the True elements with:

frame.loc[(frame['RR'].str.contains("^[^123]", na=False)), 'RR'].isin(series1.str.slice(1))[lambda df: df].index

Upvotes: 1

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