csv文件的内容：

Question

好的，我一直在网站上搜索解决方案，我发现了一些，但这些情况对我不利，主要是因为他们在'wb'中使用csv模式文件，这是我的问题的论点是不同的，我使用DictReader和Writer。我基本上，我想循环我的csv文件中的数据，如果数据匹配什么放在delete_entry内，我想从line文件中完全删除csv。我曾经想过用line文件中的数据覆盖不需要的csv，但我不知道如何处理该解决方案。我认为这是一个合乎逻辑的解决方案，但最终发生的是每一行都被删除。

import csv
def delete_information_method():
    #a tkinter entry
    global delete_entry
    #opening csv in read
    with open('employees.csv' , 'r') as emp_read:
        #creating our dictreader
        csv_dictreader = csv.DictReader(emp_read)
        #opening csv file again in write mode
        with open ('employees.csv' , 'w') as emp_write:
            #creating our writer
            csv_writer1 = csv.writer(emp_write)
            #our loop to check each line inside of our csv file is equal to what is inside the delete entry
            for line in csv_dictreader:
                if line['employee id'] == str(delete_entry):
                    del line

csv文件的内容：

first name,last name,email,DOB,adress,position,employee salary,employee id
ronald,colyar,N/A,1-1-2029 ,11245 s. plaski,software dev,233333,233

Answer 1

这里有几点：

您需要以rb / wb模式打开文件（如果在Python 2上）或在处理CSV文件时使用Python 3上的newline=''参数。至少如果您的数据中可能出现换行符。
当文件仍然可供阅读时，您无法打开该文件，特别是因为此时您还没有从中读取任何数据。
< / LI>
你永远不会写任何文件。你唯一要做的就是在写模式下打开它（它将它作为第一件事将其删除）。

最好使用不同的输出文件：

#assuming Python 3
def delete_information_method():
    #a tkinter entry
    global delete_entry
    #opening csv in read
    with open('employees.csv' , 'r', newline='') as emp_read:
        #creating our dictreader
        csv_dictreader = csv.DictReader(emp_read)
        fieldnames = csv_dictreader.fieldnames
        #opening new csv file in write mode
        with open ('employees_out.csv' , 'w', newline='') as emp_write:
            #creating our writer
            csv_writer1 = csv.DictWriter(emp_write, fieldnames=fieldnames)
            csv_writer1.writeheader()
            #our loop to check each line inside of our csv file is equal to what is inside the delete entry
            for line in csv_dictreader:
                if line['employee id'] != str(delete_entry.get()):
                    csv_writer1.writerow(line)

如果您不想这样做，请阅读整个文件，然后再写下来：

def delete_information_method():
    #a tkinter entry
    global delete_entry
    #opening csv in read
    with open('employees.csv' , 'r', newline='') as emp_read:
        #creating our dictreader
        csv_dictreader = csv.DictReader(emp_read)
        fieldnames = csv_dictreader.fieldnames
        contents = [line for line in csv_dictreader]
    #opening csv file in write mode
    with open ('employees.csv' , 'w', newline='') as emp_write:
        #creating our writer
        csv_writer1 = csv.DictWriter(emp_write, fieldnames=fieldnames)
        csv_writer1.writeheader()
        #our loop to check each line inside of our csv file is equal to what is inside the delete entry
        for line in contents:
            if line['employee id'] != str(delete_entry.get()):
                csv_writer1.writerow(line)

Answer 2

正如已经说过的那样。不要将输入与输出混合。另外，请阅读有关DictReader和DictWrite工作原理的文档： https://docs.python.org/2/library/csv.html#csv.DictReader https://docs.python.org/2/library/csv.html#csv.DictWriter

现在正在使用代码：

def delete_information_method():
    # First, read input
    new_records = []
    with open('employees.csv', 'r') as emp_read:
        csv_dictreader = csv.DictReader(emp_read)
        for record in csv_dictreader:
            # Note: you do not need to mark delete_entry as global
            # Since you are only using it to get and not updating it
            if record['employee id'] != str(delete_entry):
                new_records.append(record)

    # Now you have all records you care about and now you can
    # write it into output
    #
    # BTW, since it is different block than
    # with open('employees.csv'...
    # There you can safely use same file name if you want/need
    with open('output.csv', 'w') as emp_writer:
        csv_writer = csv.DictWriter(
            emp_writer,
            # This is important since you are using dicts to 
            # work with csv
            fieldnames=csv_dictreader.fieldnames
        )
        # Do not forget header row
        csv_writer.writeheader()
        for record in new_records:
            csv_writer.writerow(record)

我怎样才能完全摆脱我的csv文件中的一行？

csv文件的内容：

2 个答案: