Python – 将列表字典写入 CSV

在本文中，我们将讨论如何将列表字典写入 CSV 的实际实现。

我们可以为此使用 csv 模块。 csvwriter文件对象支持csvwriter.writerow()、csvwriter.writerows()、csvwriter.writeheader()三种方法。

语法：

csv.writer(csvfile, dialect='excel')

参数：

• csvfile：具有 write() 方法的文件对象。
• dialect（可选）：要使用的方言的名称。

方法 1：使用 csv.writerow()

要将列表字典写入 CSV 文件，必要的函数是 csv.writer()、csv.writerow()。此方法一次写入一行。可以使用此方法写入字段行。

句法 ：

csvwriter.writerow(row)

示例 1 ：

Python3

# import the csv package
import csv
 
# create a csv file with desired name and
# store it in a variable
with open('test.csv', 'w') as testfile:
     
    # pass the the temporary variable to
    # csv.writer function
    csvwriter = csv.writer(testfile,)
     
    # use writerow function to insert a
    # single row to the csv file.
    csvwriter.writerow(['col1', 'col2', 'col3',
                        'col4', 'col5'])

输出：

或者，可以仅使用 csv.writerow()函数将列表字典转换为 CSV 文件，只需遍历字典中的每个键值对，如图所示

示例 2：

Python3

# create a dictionary of list
test = {'Age': [52, 24, 31, 47, 51, 61],
        'Sex': ['F', 'M', 'M', 'F', 'F', 'M'],
        'height': [143, 163, 144, 154, 174, 177],
        'weight': [77, 66, 59, 53, 71, 63], }
 
# create a csv file called test.csv and
# store it a temp variable as outfile
with open("test.csv", "w") as outfile:
   
   # pass the csv file to csv.writer.
    writer = csv.writer(outfile)
     
    # convert the dictionary keys to a list
    key_list = list(test.keys())
     
    # find th length of the key_list
    limit = len(key_list)
     
    # the length of the keys corresponds to
    # no. of. columns.
    writer.writerow(test.keys())
     
    # iterate each column and assign the
    # corresponding values to the column
    for i in range(limit):
        writer.writerow([test[x][i] for x in key_list])

输出：

方法 2：使用 csv.writerows()

要将列表字典写入 CSV 文件，必要的函数是 csv.writer()、csv.writerows()。此方法将行中的所有元素（如上所述的行对象的可迭代）写入写入者的文件对象。

句法

csvwriter.writerows(rows)

示例 1 ：

Python3

# import the csv package
import csv
 
# create a file called test.csv
# and store it in a temporary variable
with open('test.csv', 'w') as testfile:
   
    # pass the temp variable to csv.writer
    # function
    csvwriter = csv.writer(testfile)
     
    # pass the row values to be stored in
    # different rows
    csvwriter.writerows([['row1'], ['row2'], ['row3'],
                         ['row4'], ['row5'], ['row6']])

输出：

示例 2：

在这里，我们将创建一个 csv 文件 test.csv 并将其作为 outfile 存储在一个变量中。

Python3

# create a dictionary of list
test = {'Age': [52, 24, 31, 47, 51, 61],
        'Sex': ['F', 'M', 'M', 'F', 'F', 'M'],
        'height': [143, 163, 144, 154, 174, 177],
        'weight': [77, 66, 59, 53, 71, 63], }
 
# create a csv file  test.csv and store
# it in a variable as outfile
with open("test.csv", "w") as outfile:
 
    # pass the csv file to csv.writer function.
    writer = csv.writer(outfile)
 
    # pass the dictionary keys to writerow
    # function to frame the columns of the csv file
    writer.writerow(test.keys())
   
    # make use of writerows function to append
    # the remaining values to the corresponding
    # columns using zip function.
    writer.writerows(zip(*test.values()))

输出：

方法 3：使用 csv.writeheader()

此方法将指定字段名称的行写入 csv.dictwriter 对象的标题。

句法

csvwriter.writeheader()

示例：

Python3

# import the csv package
import csv
 
# create a csv file with desired name
#and store it in a variable
with open('test.csv', 'w') as testfile:
   
    # store the desired header row as a list
    # and store it in a variable
    fieldnames = ['first_field', 'second_field', 'third_field']
     
    # pass the created csv file and the header
    # rows to the Dictwriter function
    writer = csv.DictWriter(testfile, fieldnames=fieldnames)
     
    # Now call the writeheader function,
    # this will write the specified rows as
    # headers of the csv file
    writer.writeheader()

输出：