Mean of several rows in pandas dataframe

Question

I have a rather big dataframe for my calculation method (SSA) - about 80000 rows. I'd like to average my data by several rows (20 for example). How can I do this?

I have a dataframe, for example:

 1. 00h         03h         06h         09h         12h
10  0.003546    0.000885    0.006852    0.00171     0.001708
11  0.00667     0.012603    0.012933    0.05603     0.025855
12  0.089116    0.054549    0.022177    0.090342    0.070226
13  0.28974     0.246415    0.297231    0.399953    0.287122

And in the end, I'd like something like this:

How can I do this?

Answer 1

Use integer division by range created by length of DataFrame with numpy.arange and aggregate mean :

df = df.groupby(np.arange(len(df))//2).mean()
print (df)

        00h       03h       06h       09h       12h
0  0.005108  0.006744  0.009893  0.028870  0.013782
1  0.189428  0.150482  0.159704  0.245147  0.178674