CODEWITHSUNDEEP
pythonpandas
J.Komodo
J.Komodo

Reputation: 101

I want to delete the first n entries in a column in pandas dataframe

I have a data file, when I import it into pandas I have

Index        DATE_TIME            Parameter
0         13/1/2016 03.45            0
1         13/1/2016 04.45            13
2         13/1/2016 05.00           27.6
3         13/1/2016 06.45            0
4         13/1/2016 07.00            1

I want to delete the first 1000 entries from the parameters column without deleting the DATE_TIME column, leaving the top part of parameter blank.

This is probably really simple but I can't seem to find the right command.

Thanks for any help.

Upvotes: 1

Views: 363

Answers (1)

EdChum
EdChum

Reputation: 394041

You can do this using loc and passing the first N entries from the index:

In [120]:
df.loc[df.index[:2], 'Parameter'] = np.NaN
df

Out[120]:
       Index  DATE_TIME  Parameter
0  13/1/2016       3.45        NaN
1  13/1/2016       4.45        NaN
2  13/1/2016       5.00       27.6
3  13/1/2016       6.45        0.0
4  13/1/2016       7.00        1.0

This will operate on a view rather than a copy

You assign whatever value you wish, here I assign NaN

Upvotes: 2

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