【轉】Pandas的Apply函數——Pandas中最好用的函數

 

 

 

 

轉自：https://blog.csdn.net/qq_19528953/article/details/79348929

---

 

import pandas as pd
import datetime   #用來計算日期差的包

def dataInterval(data1,data2):
    d1 = datetime.datetime.strptime(data1, '%Y-%m-%d')
    d2 = datetime.datetime.strptime(data2, '%Y-%m-%d')
    delta = d1 - d2
    return delta.days

def getInterval(arrLike):  #用來計算日期間隔天數的調用的函數
    PublishedTime = arrLike['PublishedTime']
    ReceivedTime = arrLike['ReceivedTime']
#    print(PublishedTime.strip(),ReceivedTime.strip())
    days = dataInterval(PublishedTime.strip(),ReceivedTime.strip())  #注意去掉兩端空白
    return days

if __name__ == '__main__':    
    fileName = "NS_new.xls";
    df = pd.read_excel(fileName) 
    df['TimeInterval'] = df.apply(getInterval , axis = 1)

　　

import pandas as pd
import datetime   #用來計算日期差的包

def dataInterval(data1,data2):
    d1 = datetime.datetime.strptime(data1, '%Y-%m-%d')
    d2 = datetime.datetime.strptime(data2, '%Y-%m-%d')
    delta = d1 - d2
    return delta.days

def getInterval_new(arrLike,before,after):  #用來計算日期間隔天數的調用的函數
    before = arrLike[before]
    after = arrLike[after]
#    print(PublishedTime.strip(),ReceivedTime.strip())
    days = dataInterval(after.strip(),before.strip())  #注意去掉兩端空白
    return days


if __name__ == '__main__':    
    fileName = "NS_new.xls";
    df = pd.read_excel(fileName) 
    df['TimeInterval'] = df.apply(getInterval_new , 
      axis = 1, args = ('ReceivedTime','PublishedTime'))    #調用方式一
    #下面的調用方式等價於上面的調用方式
    df['TimeInterval'] = df.apply(getInterval_new , 
      axis = 1, **{'before':'ReceivedTime','after':'PublishedTime'})  #調用方式二
    #下面的調用方式等價於上面的調用方式
    df['TimeInterval'] = df.apply(getInterval_new , 
      axis = 1, before='ReceivedTime',after='PublishedTime')  #調用方式三

　　

修改后的getInterval_new函數多了兩個參數，這樣我們在使用apply函數的時候要自己
傳遞參數，代碼中顯示的三種傳遞方式都行。

最后，本篇的全部代碼在下面這個網頁可以下載：

https://github.com/Dongzhixiao/Python_Exercise/tree/master/pandas_apply