在Python中讀取和打印特定行

Question

我目前正在做一些GCSE計算機科學Python編程，但是遇到了一些問題，而且似乎找不到答案。

我有一段代碼可以從文件中讀取並打印文件的一部分。 我的代碼如下所示：

#Welcome Message
print("Hello and welcome to the client activity recorder. \nHere you will be able to see and asign exercise levels to clients.")

#Open file for reading.
client_file_read = open("clientIntensity.txt","r")
print_content = client_file_read.read()
print(print_content)

#Client Selection
print("Please type the client ID of the person you wish to check what relevant activities apply:")
client_ID = input()
if client_ID == ("NeQua"):
    with open("exerciseActivities.txt") as f:
        print("For the supplied Client ID the following activities are available: \n")
        for x in range (6):
            line = f.readline()
            print(line)
            f.close
elif client_ID == ("RoDen"):
    with open("exerciseActivities.txt") as f:
        print("For the supplied Client ID the following activities are available: \n")
        for x in range (6):
            line = f.readline()
            print(line)
            f.close
elif client_ID == ("BrFre"):
    with open("exerciseActivities.txt") as f:
        print("For the supplied Client ID the following activities are available: \n")
        for x in range (6):
            line = f.readline()
            print(line)
            f.close
elif client_ID == ("KaDat"):
    with open("exerciseActivities.txt") as f:
        print("For the supplied Client ID the following activities are available: \n")
        for x in range (6):
            line = f.readline()
            print(line)
            f.close
elif client_ID == ("ViRil"):
    with open("exerciseActivities.txt") as f:
        print("For the supplied Client ID the following activities are available: \n")
        for x in range (6):
            line = f.readline()
            print(line)
            f.close
elif client_ID == ("TrGeo"):
    with open("exerciseActivities.txt") as f:
        print("For the supplied Client ID the following activities are available: \n")
        for x in range (6):
            line = f.readline()
            print(line)
            f.close
else:
    with open("exerciseActivities.txt") as f:

以下是我用來讀取文件的副本：

High 
Running
Swimming
Aerobics
Football
Tennis

Moderate
Walking
Hiking
Cleaning
Skateboarding
Basketball

如您所見，elif子程序都打印文件的前6行，但在最后一個else命令中，我希望程序打印上面文件的后6行。 非常感謝您的幫助，因為我已經精疲力竭了。

Answer 1

只需打開文件，將前六行和我們存儲in ：

with open("exerciseActivities.txt") as f:
    first_six = [next(f) for _ in range(6)]
    if client_ID in {"NeQua","RoDen","BrFre","KaDat","ViRil","TrGeo"}:
        print("For the supplied Client ID the following activities are available: \n")      
        for line in first_six:
            print(line)
    else:
        next(f) # skip empty line
        for line in f:
            print(line)

文件對象返回其自己的迭代器，因此在第一個[next(f) for _ in range(6)] ，文件指針將位於第七行，因此我們從其他地方開始。 if client_ID == "NeQua"等，您每次都執行相同的操作。因此，使用in進行成員資格測試將查看client_ID是否等於您要檢查的任何字符串，否則，我們將打印最后六行。

Answer 2

這是打印最后6行的一種方法：

from collections import deque

with open("exerciseActivities.txt", 'r') as f:
    last6_lines = deque(f, 6)
    x = list(last6_lines)
    y = ''.join(x)
    print (y)