创建并写入csv文件

下面的示例演示创建和写入csv文件。 要使一个动态文件写入器，我们需要导入一个包import csv，然后需要创建一个文件引用的文件实例 Ex:-使用open("D:\sample.csv"，"w"，newline="")作为文件写入器

here if the file does not exist with the mentioned file directory then python will create a same file in the specified directory, and "w" represents write, if you want to read a file then replace "w" with "r" or to append to existing file then "a". newline="" specifies that it removes an extra empty row for every time you create row so to eliminate empty row we use newline="", create some field names(column names) using list like fields=["Names","Age","Class"], then apply to writer instance like writer=csv.DictWriter(file_writer,fieldnames=fields) here using Dictionary writer and assigning column names, to write column names to csv we use writer.writeheader() and to write values we use writer.writerow({"Names":"John","Age":20,"Class":"12A"}) ,while writing file values must be passed using dictionary method , here the key is column name and value is your respective key value

import csv 

with open("D:\\sample.csv","w",newline="") as file_writer:

   fields=["Names","Age","Class"]

   writer=csv.DictWriter(file_writer,fieldnames=fields)

   writer.writeheader()

   writer.writerow({"Names":"John","Age":21,"Class":"12A"})

使用python的csv模块来读写逗号或制表符分隔的文件。csv模块是首选，因为它可以很好地控制引用。

例如，下面是你的工作示例:

import csv
data = ["value %d" % i for i in range(1,4)]

out = csv.writer(open("myfile.csv","w"), delimiter=',',quoting=csv.QUOTE_ALL)
out.writerow(data)

生产:

"value 1","value 2","value 3"

另一种方法，你可以在pandas中使用DataFrame: 它可以很容易地将数据转储到csv，就像下面的代码:

import pandas
df = pandas.DataFrame(data={"col1": list_1, "col2": list_2})
df.to_csv("./file.csv", sep=',',index=False)

下面是Python 3的复制粘贴示例。使用选项定义自己的分隔符和引号字符。

import csv

mylist = ['value 1', 'value 2', 'value 3']

with open('employee_file.csv', mode='w') as employee_file:
    employee_writer = csv.writer(employee_file, delimiter=',', quotechar='"', quoting=csv.QUOTE_ALL)
    employee_writer.writerow(mylist)

这会生成employee_file.csv，如下所示:

"value 1","value 2","value 3"

NOTE: If quoting is set to csv.QUOTE_MINIMAL, then .writerow() will quote fields only if they contain the delimiter or the quotechar. This is the default case. If quoting is set to csv.QUOTE_ALL, then .writerow() will quote all fields. If quoting is set to csv.QUOTE_NONNUMERIC, then .writerow() will quote all fields containing text data and convert all numeric fields to the float data type. If quoting is set to csv.QUOTE_NONE, then .writerow() will escape delimiters instead of quoting them. In this case, you also must provide a value for the escapechar optional parameter.

下面是另一个不需要csv模块的解决方案。

print ', '.join(['"'+i+'"' for i in myList])

例子:

>>> myList = [u'value 1', u'value 2', u'value 3']
>>> print ', '.join(['"'+i+'"' for i in myList])
"value 1", "value 2", "value 3"

但是，如果初始列表包含一些“，则不会转义。如果需要，可以调用一个函数像这样转义它:

print ', '.join(['"'+myFunction(i)+'"' for i in myList])

创建并写入csv文件

下面的示例演示创建和写入csv文件。 要使一个动态文件写入器，我们需要导入一个包import csv，然后需要创建一个文件引用的文件实例 Ex:-使用open("D:\sample.csv"，"w"，newline="")作为文件写入器

here if the file does not exist with the mentioned file directory then python will create a same file in the specified directory, and "w" represents write, if you want to read a file then replace "w" with "r" or to append to existing file then "a". newline="" specifies that it removes an extra empty row for every time you create row so to eliminate empty row we use newline="", create some field names(column names) using list like fields=["Names","Age","Class"], then apply to writer instance like writer=csv.DictWriter(file_writer,fieldnames=fields) here using Dictionary writer and assigning column names, to write column names to csv we use writer.writeheader() and to write values we use writer.writerow({"Names":"John","Age":20,"Class":"12A"}) ,while writing file values must be passed using dictionary method , here the key is column name and value is your respective key value

import csv 

with open("D:\\sample.csv","w",newline="") as file_writer:

   fields=["Names","Age","Class"]

   writer=csv.DictWriter(file_writer,fieldnames=fields)

   writer.writeheader()

   writer.writerow({"Names":"John","Age":21,"Class":"12A"})