[英]Find maximum value of each day from hourly data
I have problem getting max value of each day from hourly data.我在从每小时数据中获取每天的最大值时遇到问题。 Original file contain 24 data for each name each day(there are too many name).原始文件每天包含每个名称的 24 个数据(名称太多)。 as example here is 24 data for one name:例如,这里是一个名称的 24 个数据:
Start Time Period name value
2/23/2019 0:00 60 MBTS_H2145X 100
2/23/2019 1:00 60 MBTS_H2145X 100
2/23/2019 2:00 60 MBTS_H2145X 1
2/23/2019 3:00 60 MBTS_H2145X 1
2/23/2019 4:00 60 MBTS_H2145X 1
2/23/2019 5:00 60 MBTS_H2145X 2324
2/23/2019 6:00 60 MBTS_H2145X 2323
2/23/2019 7:00 60 MBTS_H2145X 2323
2/23/2019 8:00 60 MBTS_H2145X 2323
2/23/2019 9:00 60 MBTS_H2145X 2323
2/23/2019 10:00 60 MBTS_H2145X 2323
2/23/2019 11:00 60 MBTS_H2145X 2323
2/23/2019 12:00 60 MBTS_H2145X 1
2/23/2019 13:00 60 MBTS_H2145X 21
2/23/2019 14:00 60 MBTS_H2145X 21
2/23/2019 15:00 60 MBTS_H2145X 23
2/23/2019 16:00 60 MBTS_H2145X 350
2/23/2019 17:00 60 MBTS_H2145X 323
2/23/2019 18:00 60 MBTS_H2145X 23
2/23/2019 19:00 60 MBTS_H2145X 23
2/23/2019 20:00 60 MBTS_H2145X 2323
2/23/2019 21:00 60 MBTS_H2145X 23
2/23/2019 22:00 60 MBTS_H2145X 23
2/23/2019 23:00 60 MBTS_H2145X 2
the result I get is: (which is wrong and should be 2324)我得到的结果是:(这是错误的,应该是 2324)
Start Time name max value
0 2/23/2019 MBTS_H2145X 350
I have below codes but I get wrong result我有以下代码,但我得到错误的结果
import dask.dataframe as dd
import numpy as np
import pandas as pd
filename='V.csv'
df = dd.read_csv(filename, dtype='str')
#_________changing date format
df['Start Time'] = df['Start Time'].map(lambda x: pd.to_datetime(x, errors='coerce'))
#_________change to pure date without hour
df['Start Time'] = df['Start Time'].dt.date
grouped_df=(df.groupby(['Start Time','name']).agg({'value':'max'}).rename(columns={'value':'max value'}).reset_index())
grouped_df.to_csv('e1.csv')
print(grouped_df.head(12))
Keep your code the exact same.保持您的代码完全相同。 Just Change this line to:只需将此行更改为:
grouped_df=(df.groupby(['Start Time','name']).agg({'value':'max'}).rename(columns={'value':'max value'}).reset_index())
Change to:改成:
df.value = pd.to_numeric(df.value)
grouped_df= (df.groupby(['Start Time','name'])['value'].max().rename(columns={'value':'max value'}).reset_index()
df = pd.merge(df, grouped_df, on = ['Start Time','name'])
There might be something happening with the aggregate function.聚合函数可能会发生一些事情。
OR IF YOUR DTYPE IS JUST STRING, then just add the pd.to_numeric line, and keep everything else the same.或者,如果您的 DTYPE 只是字符串,则只需添加 pd.to_numeric 行,并保持其他所有内容相同。
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