Pandas : Finding correct time window - python-3.x

Question

I have a pandas dataframe which gets updated every hour with latest hourly data. I have to filter out IDs based upon a threshold, i.e. PR_Rate > 50 and CNT_12571 < 30 for 3 consecutive hours from a lookback period of 5 hours. I was using the below statements to accomplish this:
df_thld=df[(df['Date'] > df['Date'].max() - pd.Timedelta(hours=5))& (df.PR_Rate>50) & (df.CNT_12571 < 30)]
df_thld.loc[:,'HR_CNT'] = df_thld.groupby('ID')['Date'].nunique().to_frame('HR_CNT').reset_index()
df_thld[(df_thld['HR_CNT'] >3]
The problem with this approach is that since lookback period requirement is 5 hours, so, this HR_CNT can count any non consecutive hours breaching this critieria.
MY Dataset is as below:
DataFrame
Date IDs CT_12571 PR_Rate
16/06/2021 10:00 A1 15 50.487
16/06/2021 11:00 A1 31 40.806
16/06/2021 12:00 A1 25 52.302
16/06/2021 13:00 A1 13 61.45
16/06/2021 14:00 A1 7 73.805
In the above Dataframe, threshold was not breached at 1100 hrs, but while counting the hours, 10,12 and 13 as the hours that breached the threshold instead of 12,13,14 as required. Each id may or may not have this critieria breached in a single day. Any idea, How can I fix this issue?

Answer 1

Please excuse me, if I have misinterpreted your problem. As I understand the issues you have a dataframe which is updated hourly. An example of this dataframe is illustrated below as df. From this dataframe, you want to filter only those rows which satisfy the following two conditions:
PR_Rate > 50 and CNT_12571 < 30
If and only if the threshold is surpassed for three consecutive hours
Given these assumptions, I would proceed as follows:
df:
Date IDs CT_1257 PR_Rate
0 2021-06-16 10:00:00 A1 15 50.487
1 2021-06-16 12:00:00 A1 31 40.806
2 2021-06-16 14:00:00 A1 25 52.302
3 2021-06-16 15:00:00 A1 13 61.450
4 2021-06-16 16:00:00 A1 7 73.805
Note in this dataframe, the only time fr5ame which satisfies the above conditions is the entries for the of 14:00, 15:00 and 16:00.
def filterFrame(df, dur, pr_threshold, ct_threshold):
ff = df[(df['CT_1257']< ct_threshold) & (df['PR_Rate'] >pr_threshold) ].reset_index()
ml = list(ff.rolling(f'{dur}h', on='Date').count()['IDs'])
r = len(ml)- 1
rows= []
while r >= 0:
end = r
start = None
if int(ml[r]) < dur:
r -= 1
else:
k = int(ml[r])
for i in range(k):
rows.append(r-i)
r -= k
rows = rows[::-1]
return ff.filter(items= rows, axis = 0).reset_index()
running filterFrame(df, 3, 50, 30) yields:
level_0 index Date IDs CT_1257 PR_Rate
0 1 2 2021-06-16 14:00:00 A1 25 52.302
1 2 3 2021-06-16 15:00:00 A1 13 61.450
2 3 4 2021-06-16 16:00:00 A1 7 73.805