diff --git a/doc/source/groupby.rst b/doc/source/groupby.rst index 4cde1fed344a8..484efd12c5d78 100644 --- a/doc/source/groupby.rst +++ b/doc/source/groupby.rst @@ -1014,6 +1014,23 @@ Regroup columns of a DataFrame according to their sum, and sum the aggregated on df df.groupby(df.sum(), axis=1).sum() +Groupby by Indexer to 'resample' data +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Resampling produces new hypothetical samples(resamples) from already existing observed data or from a model that generates data. These new samples are similar to the pre-existing samples. + +In order to resample to work on indices that are non-datetimelike , the following procedure can be utilized. + +In the following examples, **df.index // 5** returns a binary array which is used to determine what get's selected for the groupby operation. + +.. note:: The below example shows how we can downsample by consolidation of samples into fewer samples. Here by using **df.index // 5**, we are aggregating the samples in bins. By applying **std()** function, we aggregate the information contained in many samples into a small subset of values which is their standard deviation thereby reducing the number of samples. + +.. ipython:: python + + df = pd.DataFrame(np.random.randn(10,2)) + df + df.index // 5 + df.groupby(df.index // 5).std() Returning a Series to propagate names ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~