[英]Mean of the previous n rows
I have the following Data Frame:我有以下数据框:
date = pd.date_range('2021-01-01', periods = 21, freq = '60S')
df = pd.DataFrame({ 'Date': date,
'Type':'DM','DM','DM','DS','DS','DS','DS','DM','DS','DS','DM','DM','DM','DM','DM','DM','DM','DS','DS','DS','DM'],
'Value': [105,130,104,205,206,208,222,160,105,130,104,205,206,208,222,160,158,176,120,200,75]})
So i want to obtain the mean value in df['mean']
, but only for the condition where Type is 'DS' and the mean value must be the previous 3 rows of df['Value]
where Type is DM.所以我想获得
df['mean']
,但仅适用于 Type 为 'DS' 且平均值必须是df['Value]
的前 3 行,其中 Type 为 DM 的情况。 I should obtain something like this我应该得到这样的东西
Output Output
Type Value mean
0 DM 105 NaN
1 DM 130 NaN
2 DM 104 NaN
3 DS 205 113
4 DS 206 113
5 DS 208 113
6 DS 222 113
7 DM 160 NaN
8 DS 105 131,33
9 DS 130 131,33
10 DM 104 NaN
11 DM 205 NaN
12 DM 206 NaN
13 DM 208 NaN
14 DM 222 NaN
15 DS 160 212
16 DM 158 NaN
17 DS 176 196
18 DS 120 196
19 DS 200 196
20 DM 75 NaN
I tried with grouby, but i manage to obtain a result only for a equal df['Type']
of value (if the value is 'DM' the mean value i obtain is with the previous 'DM' Values).我尝试使用 grouby,但我设法仅获得相等
df['Type']
值的结果(如果该值为“DM”,则我获得的平均值与之前的“DM”值相同)。
The code i tried: df['Avg_Back'] = ((df.groupby('Type')['Value'].rolling(window=4).mean().reset_index(level=0,drop=True))*4 - df['NOx'])/3
我试过的代码:
df['Avg_Back'] = ((df.groupby('Type')['Value'].rolling(window=4).mean().reset_index(level=0,drop=True))*4 - df['NOx'])/3
But, i don't know how to use it to calculate the mean for a different Type value.但是,我不知道如何使用它来计算不同类型值的平均值。
df["mean"] = df[df.Type == "DM"].rolling(3)["Value"].mean()
df["mean"] = df["mean"].ffill()
df.loc[df.Type == "DM", "mean"] = np.nan
print(df)
Prints:印刷:
Date Type Value mean
0 2021-01-01 00:00:00 DM 105 NaN
1 2021-01-01 00:01:00 DM 130 NaN
2 2021-01-01 00:02:00 DM 104 NaN
3 2021-01-01 00:03:00 DS 205 113.000000
4 2021-01-01 00:04:00 DS 206 113.000000
5 2021-01-01 00:05:00 DS 208 113.000000
6 2021-01-01 00:06:00 DS 222 113.000000
7 2021-01-01 00:07:00 DM 160 NaN
8 2021-01-01 00:08:00 DS 105 131.333333
9 2021-01-01 00:09:00 DS 130 131.333333
10 2021-01-01 00:10:00 DM 104 NaN
11 2021-01-01 00:11:00 DM 205 NaN
12 2021-01-01 00:12:00 DM 206 NaN
13 2021-01-01 00:13:00 DM 208 NaN
14 2021-01-01 00:14:00 DM 222 NaN
15 2021-01-01 00:15:00 DS 160 212.000000
16 2021-01-01 00:16:00 DM 158 NaN
17 2021-01-01 00:17:00 DS 176 196.000000
18 2021-01-01 00:18:00 DS 120 196.000000
19 2021-01-01 00:19:00 DS 200 196.000000
20 2021-01-01 00:20:00 DM 75 NaN
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.