# csv --- CSV File Reading and Writing — Examples

> The simplest example of reading a CSV file import csv with open('some.csv', newline='') as f: reader = csv.reader(f) for row in reader: print(row) Reading a file with an alternate format import csv with open('passwd', newline='') as f: reader = csv.reader(f, delimiter=':', quoting=csv.QUOTE_NONE) fo

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## Knowledge

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The simplest example of reading a CSV file

import csv with open('some.csv', newline='') as f: reader = csv.reader(f) for row in reader: print(row)

Reading a file with an alternate format

import csv with open('passwd', newline='') as f: reader = csv.reader(f, delimiter=':', quoting=csv.QUOTE_NONE) for row in reader: print(row)

The corresponding simplest possible writing example is

import csv with open('some.csv', 'w', newline='') as f: writer = csv.writer(f) writer.writerows(someiterable)

Since open is used to open a CSV file for reading, the file will by default be decoded into unicode using the system default encoding (see locale.getencoding). To decode a file using a different encoding, use the encoding argument of open

import csv with open('some.csv', newline='', encoding='utf-8') as f: reader = csv.reader(f) for row in reader: print(row)

The same applies to writing in something other than the system default encoding: specify the encoding argument when opening the output file.

Registering a new dialect

import csv csv.register_dialect('unixpwd', delimiter=':', quoting=csv.QUOTE_NONE) with open('passwd', newline='') as f: reader = csv.reader(f, 'unixpwd')

A slightly more advanced use of the reader --- catching and reporting errors

import csv, sys filename = 'some.csv' with open(filename, newline='') as f: reader = csv.reader(f) try: for row in reader: print(row) except csv.Error as e: sys.exit(f'file {filename}, line {reader.line_num}: {e}')

And while the module doesn't directly support parsing strings, it can easily be done

import csv for row in csv.reader(['one,two,three']): print(row)

will not be interpreted correctly, and on platforms that use \r\n line endings on write an extra \r will be added. It should always be safe to specify newline='', since the csv module does its own (universal ) newline handling.

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