Question

我的csv文件的数据格式如下 date,time,event,user,net。我需要遍历这个文件的每一行，如果event == start，继续直到它到达同一用户和网络的事件==结束，然后计算两个事件之间的时差。我有这段代码：

import csv
import datetime
import time

with open('dates.csv', 'rb') as csv_file:
    csv_read = csv.reader(csv_file)
    for row in csv_read:
        if row[2]=="start":
            n1=datetime.datetime.strptime(row[1], '%H:%M:%S')

            for row2 in csv_read:
                if (row2[2]=="End" and row[3]==row2[3] and row[4]==row2[4]):
                    n2=datetime.datetime.strptime(row2[1], '%H:%M:%S')

                    print row[2],row[1], row2[2], row2[1]

                    diff = n2 - n1
                    print "time difference = ", diff.seconds
                    break

但是这段代码的问题是当它找到匹配时＃34;结束＆＃34;并计算时间，它将在匹配后开始搜索＆＃34;结束＆＃34;，忽略前面的行。作为一个例子

May,20,9:02:22,2010,start,user1,net-3
May,20,9:02:23,2010,start,user1,net-3
May,20,9:02:55,2010,start,user1,net-2
May,20,9:02:55,2010,End,user1,net-3
May,20,9:03:43,2010,End,user1,net-2
May,20,9:02:55,2010,End,user1,net-3
May,20,9:03:43,2010,End,user1,net-2
May,20,9:03:44,2010,start,user1,net-2
May,20,9:03:49,2010,End,user1,net-2

只会产生以下输出：

Connect 9:02:22 Disconnect 9:02:55
time difference =  33
Connect 9:03:44 Disconnect 9:03:49
time difference =  5

那么有人知道如何解决这个问题吗？还可以将时差作为额外列添加到现有数据中吗？

感谢

我已经更新了代码，但是现在我遇到了一个新问题，我的文件包含35734行，但输出文件只包含350行，我很困惑为什么会发生这种情况，谢谢，我将不胜感激更新的代码：

l1=[]  ## empty list
l2=[]  ## empty list

csv_file=open('dates_read.csv', 'r+')
csv_wfile=open('dates_write.csv', 'w+')

csv_read = csv.reader(csv_file)
csv_read1 = csv_read
csv_write = csv.writer(csv_wfile)
for row in csv_read:
    s=csv_read.line_num
    if (row[4]=="start" and (s not in l1)):
        n1=datetime.datetime.strptime(row[2], '%H:%M:%S')

        l1.append(s)
        month = str(row[0])
        day = int(row[1])
        time = str(row[2])
        year = int(row[3])
        user = str(row[5])
        net = str(row[6])
        dwell_time = str(row[7])
        for row2 in csv_read1:
            e=csv_read1.line_num
            if (row2[4]=="End" and row[5]==row2[5] and row[6]==row2[6] and (csv_read1.line_num not in l2)and s<e):
                n2=datetime.datetime.strptime(row2[2], '%H:%M:%S')
                diff = n2 - n1
                dwell_time= diff
                print("time difference = ", diff.seconds,"\n")
                csv_write.writerow([month, day, time, year, user, net, dwell_time])
                l2.append(e)
                break
print (s) #prints 818
print (e) #prints 35734

Answer 1

您的代码唯一的问题是，在遇到第一个 START 后，您正在遍历 END 关键字的行。相反，它应该从头开始遍历文件的行。有了这个，我们还必须考虑到同一条线不会再次被遍历。为此，我们可以使用一个列表，该列表可以保存已经遍历的行的行号。

我没有编写新代码，只对代码进行了更改。

>>> l=[]  ## empty list
>>> csv_file=open('dates.csv')
>>> csv_read = csv.reader(csv_file)
>>> for row in csv_read:
            if row[0].split()[4]=="start":
                n1=datetime.datetime.strptime(row[0].split()[2], '%H:%M:%S')
                s=csv_read.line_num
                csv_file1=open('/Python34/Workspace/Stoverflow/dates.csv')
                csv_read1 = csv.reader(csv_file1)
                for row2 in csv_read1:
                    e=csv_read1.line_num
                    ## Inside if iam adding to more checks that verify that the same line is not traversed again and the END flag is always encountered after START flag
                    if (row2[0].split()[4]=="End" and row[0].split()[6]==row2[0].split()[6] and row[0].split()[5]==row2[0].split()[5] and (csv_read1.line_num not in l) and s<csv_read1.line_num):
                        n2=datetime.datetime.strptime(row2[0].split()[2], '%H:%M:%S')
                        print("Connect : ",row[0].split()[2]," Disconnect :",row2[0].split()[2])
                        diff = n2 - n1
                        print("time difference = ", diff.seconds,"\n")
                        l.append(csv_read1.line_num)
                        del csv_read1
                    break
            del csv_file1

Answer 2

我觉得使用地图解决这个问题会更好。

将（user_id，net_id）定义为键，将（start_status，start_time）定义为值，如下所示：

class UserNet:
   user_id = -1
   net_id = -1
   // Other Operation

class StartStatus:
   start_flag = False
   start_time = -1
   // Other Operation

当您读取一行时，首先判断该行中的状态字符串是START还是END。

如果结束，则使用从该行读取以在新地图结构中查找，找到start_time和minus以获得答案。

如果它是START，则将该值插入新的地图结构中。

如果您不想要错误判断，那么

start_flag是不必要的，它的标志代表重复启动，也许您不需要它。

使用python计算文件中条目之间的时间差

2 个答案: