cpython: c63d7374b89a (original) (raw)

--- a/Doc/library/csv.rst +++ b/Doc/library/csv.rst @@ -11,15 +11,15 @@ pair: data; tabular The so-called CSV (Comma Separated Values) format is the most common import and -export format for spreadsheets and databases. There is no "CSV standard", so -the format is operationally defined by the many applications which read and -write it. The lack of a standard means that subtle differences often exist in -the data produced and consumed by different applications. These differences can -make it annoying to process CSV files from multiple sources. Still, while the -delimiters and quoting characters vary, the overall format is similar enough -that it is possible to write a single module which can efficiently manipulate -such data, hiding the details of reading and writing the data from the -programmer. +export format for spreadsheets and databases. CSV format was used for many +years prior to attempts to describe the format in a standardized way in +:rfc:4180. The lack of a well-defined standard means that subtle differences +often exist in the data produced and consumed by different applications. These +differences can make it annoying to process CSV files from multiple sources. +Still, while the delimiters and quoting characters vary, the overall format is +similar enough that it is possible to write a single module which can +efficiently manipulate such data, hiding the details of reading and writing the +data from the programmer. The :mod:csv module implements classes to read and write tabular data in CSV format. It allows programmers to say, "write this data in the format preferred @@ -418,50 +418,101 @@ Examples The simplest example of reading a CSV file:: +<<<<<<< local

import csv
with f = open("some.csv", newline=''):
reader = csv.reader(f)
for row in reader:
```
   print(row)[](#l1.37)
```

+======= import csv with open('some.csv', newline='') as f: reader = csv.reader(f) for row in reader: print(row) +>>>>>>> other Reading a file with an alternate format:: +<<<<<<< local

import csv
with f = open("passwd"):
reader = csv.reader(f, delimiter=':', quoting=csv.QUOTE_NONE)
for row in reader:
```
   print(row)[](#l1.53)
```

+======= import csv with open('passwd') as f: reader = csv.reader(f, delimiter=':', quoting=csv.QUOTE_NONE) for row in reader: print(row) +>>>>>>> other The corresponding simplest possible writing example is:: +<<<<<<< local

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

+>>>>>>> other Since :func: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 :func:locale.getpreferredencoding). To decode a file using a different encoding, use the encoding argument of open:: +<<<<<<< local

import csv
f = open("some.csv", newline='', encoding='utf-8'):
reader = csv.reader(f)
for row in reader:
```
   print(row)[](#l1.86)
```

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

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

   reader = csv.reader(f, 'unixpwd')[](#l1.104)

for row in reader:
```
   pass[](#l1.106)
```

+======= import csv csv.register_dialect('unixpwd', delimiter=':', quoting=csv.QUOTE_NONE) with open('passwd') as f: reader = csv.reader(f, 'unixpwd') +>>>>>>> other A slightly more advanced use of the reader --- catching and reporting errors:: +<<<<<<< local

import csv, sys
filename = "some.csv"
with f = open(filename, newline=''):
reader = csv.reader(f)
try:
```
   for row in reader:[](#l1.122)
```
```
  print(row)[](#l1.123)
```
except csv.Error as e:

   sys.exit('file {}, line {}: {}'.format(filename, reader.line_num, e))[](#l1.125)

+======= import csv, sys filename = 'some.csv' with open(filename, newline='') as f: @@ -471,13 +522,14 @@ A slightly more advanced use of the read print(row) except csv.Error as e: sys.exit('file {}, line {}: {}'.format(filename, reader.line_num, e)) +>>>>>>> other 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)[](#l1.141)
```

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