How to use the std function on section of a pandas dataframe?

Question

I am trying to slice the array up when using the std function to only use part of it. That part being 1:t, as t is an integer that grows with each iteration of the for loop. Y is my pandas dataset and the column is 'TempK' which is specified as the column parameter. Is there a limit on much you can slice as the dataset is quite big or is it something else?

def calc_std(t, y, column):
    deviationPrediction = np.std(y.loc[1:t, [column]])
    return deviationPrediction

The error I receive is this:

Traceback (most recent call last): File "C:\Users\Kabla\Anaconda3\envs\condaEnv\Lib\site-packages\pandas\core\indexes\base.py", line 2657, in get_loc return self._engine.get_loc(key) KeyError: 1

you can do so more directly: `df.loc[start:end, [columns]].std()` — Quang Hoang, Apr 17 '19 at 14:34
yes, it iterates through the whole df. As i call the function from a for loop, t wont always be the end. can i substitute end for t? — user3697903, Apr 17 '19 at 14:34
Can you `print(y)` and post the output? it seems to me that there is no row called "1". Maybe y is indexed in a particular way? — luca.vercelli, Apr 17 '19 at 15:41

score 1 · Accepted Answer · edited Dec 29 '21 at 04:48

1

From the docs for loc:

note that 5 is interpreted as a label of the index, and never as an integer position along the index

edited Dec 29 '21 at 04:48

Henry Ecker

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answered Apr 17 '19 at 15:54

luca.vercelli

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How to use the std function on section of a pandas dataframe?

1 Answers1