计算结果未添加到现有 csv

Question

我尝试将输出作为新列写入 csv 文件。我可以转换并打印日期和时间，但无法将其写入与“Arrival_time”列中相同的 csv。代码运行正常，没有错误，但 csv 列“到达时间”中没有值。

我哪里错了？

    import pandas as pd

df = pd.read_csv ('C:/New.csv',sep=';')
print (df)

import datetime
import csv

#for i in range(0,len(df)):
    #row= df.iloc[i]['arrival_unix_seconds']
    #a = int(row)
    #date = datetime.datetime.utcfromtimestamp(a)
    #targetDate = date.strftime("%Y-%m-%d %H:%M:%S")
    #print(targetDate)
    
df['arrival_unix_seconds'] = df.arrival_unix_seconds.apply(lambda x: \
    (datetime.datetime.utcfromtimestamp(int(x))).strftime("%Y-%m-%d %H:%M:%S"))

print(df.arrival_unix_seconds)

with open("New.csv", "a") as inputfile:

        title = ["id", "space_id", "arrival_unix_seconds", "departure_unix_seconds", "xml_id", "Arrival_time"]
        writer = csv.DictWriter(inputfile, delimiter=';', fieldnames = title)
        writer.writerow({"Arrival_time": df.arrival_unix_seconds})

Answer 1

由于您已经在使用 pandas 并创建数据框，只需执行以下操作即可计算 Arrival_time 并将其写回现有的 csv：

import pandas as pd
import datetime

df = pd.read_csv('C:/Master thesis/Sensor/parking_operations_berlin_hannover/New.csv', sep=';')
    
df['Arrival_time'] = df.arrival_unix_seconds.apply(lambda x: (datetime.datetime.utcfromtimestamp(int(x))).strftime("%Y-%m-%d %H:%M:%S"))
    
df.to_csv('C:/Master thesis/Sensor/parking_operations_berlin_hannover/New.csv', sep=';', index=False)

计算结果未添加到现有 csv

Calculated result is not added to the existing csv

python

unix-timestamp

dataframe

export-to-csv

pandas