Filtering DataFrame Index through Array

Question

I have a sample dataframe df and an arraynas shown below. I want to filter based on the array values which are in index. The output dataframe is shown below as well. I have tried Out = df[df.index == n] and Out = df.loc[df.index == n ] which is not working giving an error Lengths must match to compare. Can anyone help me in solving this.

df = Date Open High Low Close Adj Close Volume 0 2007-06-18 0.33979 0.33979 0.33979 0.33979 0.33979 1591888 1 2007-06-29 0.33074 0.33074 0.33074 0.33074 0.33074 88440 2 2007-06-20 0.33526 0.33526 0.33526 0.33526 0.33526 3538 3 2007-06-21 0.32113 0.32113 0.32113 0.32113 0.32113 3550 4 2007-06-22 0.34713 0.34713 0.34713 0.34713 0.34713 670 6 2007-06-18 0.33979 0.33979 0.33979 0.33979 0.33979 1591888 7 2007-06-29 0.33074 0.33074 0.33074 0.33074 0.33074 88440 8 2007-06-20 0.33526 0.33526 0.33526 0.33526 0.33526 3538 9 2007-06-21 0.32113 0.32113 0.32113 0.32113 0.32113 3550 10 2007-06-22 0.34713 0.34713 0.34713 0.34713 0.34713 670

array([ 0, 1, 2, 3])

Out = Date Open High Low Close Adj Close Volume 0 2007-06-18 0.33979 0.33979 0.33979 0.33979 0.33979 1591888 1 2007-06-29 0.33074 0.33074 0.33074 0.33074 0.33074 88440 2 2007-06-20 0.33526 0.33526 0.33526 0.33526 0.33526 3538 3 2007-06-21 0.32113 0.32113 0.32113 0.32113 0.32113 3550

Tim · Accepted Answer · 2018-07-16 18:52:14Z

4

You should be able to do

out = df[df.index.isin(n)]

answered Jul 16, 2018 at 18:52

Tim

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3 Comments

Alex_MN Over a year ago

what if there is DateTime Index and my array is as shown above. Is there anyway to filter it on the basis of row number of array ? . Here the array number are row numbers

Tim Over a year ago

Sure - if the index is a datetime rather than integers, you can just use df.loc[n] .

Alex_MN Over a year ago

Thanks! but that is giving me the unhashable type: 'numpy.ndarray' error

modesitt · Accepted Answer · 2018-07-16 18:52:56Z

1

Your solutions do not work because you are trying to compare the equality value of your short array n and df.index. You can use pandas fancy-indexing to get your solution. The following will work fine if n is a np.array.

df.loc[n]

answered Jul 16, 2018 at 18:52

modesitt

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