I would like to get a rolling count of how many rows have been between the current row and the last peak. Example code:
Value | Rows since Peak
-----------------------
1 0
3 0
1 1
2 2
1 3
4 0
6 0
5 1
You can compare the values to the cummax and use it for a groupby.cumcount:
df['Rows since Peak'] = (df.groupby(df['Value'].eq(df['Value'].cummax())
.cumsum())
.cumcount()
)
How it works:
Every time a value is equal to the cumulated max (df['Value'].eq(df['Value'].cummax())) we start a new group (using cumsum to define the group). Then cumcount enumerates since the start of the group.
output:
Value Rows since Peak
0 1 0
1 3 0
2 1 1
3 2 2
4 1 3
5 4 0
6 6 0
7 5 1