使用复杂的列表数据写入 CSV 文件

Question

I'm trying to write a complex list of dictionaries to CSV, but getting encoding and value errors. I haven't really worked with data in Python, so I'm new to this.

import csv

with open("output.csv", 'rb', encoding='utf-8-sig', newline='') as f:
    writer = csv.writer(f, delimiter=",")
    for row in row_num:  
        writer.writerows(row_num)

 Traceback (most recent call last):
 File "<console>", line 1, in <module>
 ValueError: binary mode doesn't take a newline argument

If I remove the encoding, I get: io.UnsupportedOperation: write .

Here is a sample of the data that I want to write to a CSV file with header being the key like code and hid :

 [OrderedDict([('code', '7nsdjfk'), ('hid', '220'), ('name', 'sdjlnj dkldk slkdlkd'), ('code2', '99'), ('description', 'dmldc skdlmls wsldfml'), ('average', '0'), ('ccr', '0.218'), ('ccr_price', '399'), ('dusk sdks', '603'), ('dcfl lldcml', '3847.9'), ('id', 'sdklcldkcdslkcmsdl202i')]), OrderedDict([ ...]), OrderedDict([...])]

Answer 1

Changing the mode to text-plain

CSV stands for comma-separated value. This format consists on plain text.

Moreover, 'rb' means read r file as a binary b , which is incongruent with plain-text.

Try with 'wt' or just 'w' to actually write a plain-text file.

Check the python docs to learn more about the open() function.

Edit: Write data into file

I have come up with this solution:

• csv.writer is replaced by csv.DictWriter , which intakes the keys
• writer.writeheader() inserts the keys as headers separated by commas
• writer.writerows(row_num) writes the values into the file, one line per OrderedDict

from collections import OrderedDict
import csv

row_num = [OrderedDict([('code', '7nsdjfk'), ('hid', '220'), ('name', 'sdjlnj dkldk slkdlkd'), ('code2', '99'), ('description', 'dmldc skdlmls wsldfml'),
                        ('average', '0'), ('ccr', '0.218'), ('ccr_price', '399'), ('dusk sdks', '603'), ('dcfl lldcml', '3847.9'), ('id', 'sdklcldkcdslkcmsdl202i')]),
           OrderedDict([('code', 'a'), ('hid', '1'), ('name', 'b'), ('code2', '1'), ('description', 'c'),
                        ('average', '1'), ('ccr', '0.123'), ('ccr_price', '133'), ('dusk sdks', '133'), ('dcfl lldcml', '1345.9'), ('id', 'abcde')]),
        ]

keys = row_num[0].keys()

with open("output.csv", 'wt', encoding='utf-8-sig', newline='') as f:
    writer = csv.writer(f, delimiter=",")
    writer = csv.DictWriter(f, keys)
    writer.writeheader()

    # write values
    writer.writerows(row_num)

The results in output.csv are:

code,hid,name,code2,description,average,ccr,ccr_price,dusk sdks,dcfl lldcml,id
7nsdjfk,220,sdjlnj dkldk slkdlkd,99,dmldc skdlmls wsldfml,0,0.218,399,603,3847.9,sdklcldkcdslkcmsdl202i
a,1,b,1,c,1,0.123,133,133,1345.9,abcde

Answer 2

'rb' stands for 'read as binary'. So, it reads the data from the file considering equivalent of binary.

It does not take any extra arguments, as per doc. Simply use:

with open("output.csv", 'w') as f:

You can try to use 'w' in place of 'rb' mode just to write the file .

Words from the documentation....

Files opened in binary mode (including 'b' in the mode argument) return contents as bytes objects without any decoding.

Modes:

'r' - open for reading (default)
'w' - open for writing, truncating the file first
'x' - open for exclusive creation, failing if the file already exists
'a' - open for writing, appending to the end of the file if it exists
'b' - binary mode
't' - text mode (default)
'+' - open a disk file for updating (reading and writing)