How to get number of groups in a groupby object in koalas?

Question

How to get number of groups in a groupby object in koalas ?

In pandas we can use ngroups, but this method is not implemented yet in koalas.

Suppose groupby object is called dfgroup.

Any idea ?

maybe try `len(dfgroup)`... I'd try it myself but from some reason I'm unable to install koalas. — Roy Cohen, Dec 25 '20 at 22:55
It doesn't work : `object of type 'DataFrameGroupBy' has no len()` — Ousen92i, Dec 25 '20 at 23:58

score 1 · Accepted Answer · answered Dec 26 '20 at 09:55

You need to force execution of some function on that GroupBy object (type: databricks.koalas.groupby.DataFrameGroupBy), and from that you can get a length. For example, the dfgroup.size() will return databricks.koalas.series.Series on which you can call len (example is adapted from documentation):

>>> grouped = df.groupby(['Animal'])
>>> type(grouped.size())
<class 'databricks.koalas.series.Series'>
>>> len(grouped.size())
2

score 0 · Answer 2 · answered Mar 15 '23 at 03:28

0

in koalas

df1.groupby('School').first().pipe(len)

answered Mar 15 '23 at 03:28

G.G

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How to get number of groups in a groupby object in koalas?

2 Answers2