ODE TO A SHIPPING LABEL!by Carlos Bueno!!Once there was a little o,!with an accent on top like só.!!It started out as UTF8,!(universal since '98),!but the program only knew latin1,!and changed little ó to "ó" for fun.!!A second program saw the "ó"!and said "I know HTML entity!"!So "ó" was smartened to "ó"!and passed on through happily.!!Another program saw the tangle!(more precisely, ampersands to mangle)!and thus the humble "ó"!became "ó"
Character Encoding & Unicode How to (╯°□°)╯︵ ┻━┻ with dignity
Esther Nam & Travis Fischer!PyCon US 2014, Montréal
Uni-wat?!
┻━┻ ︵ヽ ノ( ┻━┻
How to (╯°□°)╯︵ ┻━┻ with dignity
– Luke Sneeringer | Program Committee Chair
“You'll be pleased to know that your talk title crashed our meeting robot, which is a great argument for the relevance of this talk. :-) ...”
Python 3 is out of scope
The Fundamentals of Unicode
Humans use text. Computers speak bytes.
a -> 01100001
ASCII ISO-8859-15!(latin-9)
CP-1252!(Windows 1252) UTF-8
a 01100001 01100001 01100001 01100001
€ NA 10100100 1000000011100010 10000010 10101100
¤ NA NA 10100100 11000010 10100100
ASCII ISO-8859-15!(latin-9)
CP-1252!(Windows 1252) UTF-8
a 01100001 01100001 01100001 01100001
€ NA 10100100 1000000011100010 10000010 10101100
¤ NA NA 10100100 11000010 10100100
ASCII ISO-8859-15!(latin-9)
CP-1252!(Windows 1252) UTF-8
a 01100001 01100001 01100001 01100001
€ NA 10100100 1000000011100010 10000010 10101100
¤ NA NA 10100100 11000010 10100100
ASCII ISO-8859-15!(latin-9)
CP-1252!(Windows 1252) UTF-8
a 01100001 01100001 01100001 01100001
€ NA 10100100 1000000011100010 10000010 10101100
¤ NA NA 10100100 11000010 10100100
π — ‽ ☠ ☁ ☂ ☃ ☄ ★ ☆ ☇ ☈ ☉ ☊
☋ ☌ ☍ ☎ ☏ ☐ ☑ ☒ ☓ ☖ ☗ ☘ ☙
☚ ☛ ☜ ☝ ☞ ☟ ☠ ☡ ☢ ☣ ☤ ☥ ☦ ☧
☨ ☩ ☪ ☫ ☬ ☭ ☮ ☯ ☸ ☹ ☺ ☻ ☼ ☽ ☾ ☿ ♀ ♁ ♂ ♃ ♄ ♅ ♆ ♇ ♔ ♕ ♖ ♗ ♘ ♙ ♚ ♛ ♜ ♝ ♞ ♟ ♠ ♡ ♢ ♣ ♤ ♥
♦ ♧ ♨ ♩ ♪ ♫ ♬ ♭ ♮♯ ♰ ♲ ♳ ♻ ♼ ♽ ♾ ⚀ ⚁ ⚂ ⚃ ⚄ ⚅ ⚆ ⚇ ⚈
a -> U+0061Character Unicode Code Point
!
Unicode
a -> U+0061Character Unicode Code Point
!
Unicode
a -> U+0061 Character LATIN SMALL LETTER A
Computers speak bytes.
!
Unicode
a !
U+0061 -> 01100001Unicode Code Point Binary Encoding
!
Unicode
U+0061 -> 01100001Unicode Code Point Binary Encodinga
UTF-8Unicode Transformation Format
Unicode != UTF-8 Code Points Binary Encoding U+0061 01100001
Layers of Abstraction
• Display (Glyphs | Fonts) Let them eat cake!
• Display (Glyphs | Fonts) Let them eat cake!
!
• Text (Unicode | Code Points) U+0061
• Display (Glyphs | Fonts) Let them eat cake!
!
• Text (Unicode | Code Points) U+0061
!
• Storage (Binary | UTF-8) 01100001
Unicode & Python[Python 2.7]
str type>>>euro_bytestring = '€' !>>>type(euro_bytestring) <type 'str'>
[Python 2.7]
unicode type# € code point >>>euro_unicode = u'\u20ac' !>>>type(euro_unicode) <type 'unicode'>
[Python 2.7]
Unicode Code points u'\u20ac'
!Bytes UTF-8 '\xe2\x82\xac' !
[Python 2.7]
Unicode Code points u'\u20ac'
'\xe2\x82\xac'.decode('utf8')
!Bytes UTF-8 '\xe2\x82\xac' !
[Python 2.7]
Unicode Code points u'\u20ac'
'\xe2\x82\xac'.decode('utf8')
!Bytes UTF-8 '\xe2\x82\xac' !
[Python 2.7]
Unicode Code points u'\u20ac'
'\xe2\x82\xac'.decode('utf8')
u'\u20ac'.encode('utf8')
!Bytes UTF-8 '\xe2\x82\xac' !
[Python 2.7]
Unicode Code points u'\u20ac'
'\xe2\x82\xac'.becode('utf8')
u'\u20ac'.uncode('utf8')
!Bytes UTF-8 '\xe2\x82\xac' !
[Python 2.7]
You CANNOT infer an encoding from a bytestring
#! /usr/bin/python # -*- coding: utf8 -*- !# Opened file should be latin-1 encoded! # If it’s not, call tech support ASAP with open("input_file.csv") as input_file:
Date: Wed, 11 Apr 2014 11:15:55 -0600To: [email protected] From: [email protected] Subject: Character encoding MIME-Version: 1.0 Content-Type: text/html; charset="UTF-8"
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE html PUBLIC “-//W3C//DTD …> <html xmlns="http://www.w3.org/1999/xhtml" …>
Best Practices
Example Application
Author Review
G. van Rossum If you decide to design your own car there are thousands sort of car…
R. Ebert Every great car should feel new every time you drive it.
L. Torvalds Volvo isn’t evil, they just make really crappy cars.
Author Review
G. van Rossum If you decide to design your own car there are thousands sort of car…
R. Ebert Every great car should feel new every time you drive it.
L. Torvalds Volvo isn’t evil, they just make really crappy cars.
Application Processes Text
Author Review
G. van Rossum If you decide to design your own car there are thousands sort of car…
R. Ebert Every great car should feel new every time you drive it.
L. Torvalds Volvo isn’t evil, they just make really crappy cars.
Application Processes Text
PSQL
Author Review
G. van Rossum If you decide to design your own car there are thousands sort of car…
R. Ebert Every great car should feel new every time you drive it.
L. Torvalds Volvo isn’t evil, they just make really crappy cars.
Application Processes Text
PSQL
Encoding: Windows 1252 (CP-1252)
Montreal -> Montréal
psql=# set server_encoding to "utf-8";
My friend said: “I cannot believe this is a Volvo! I had a car just like this when I lived in Montreal.” He told me he had paid 9400€ for his.Sample Review Text
My friend said: “I cannot believe this is a Volvo! I had a car just like this when I lived in Montreal.” He told me he had paid 9400€ for his.Sample Review Text
My friend said: “I cannot believe this is a Volvo! I had a car just like this when I lived in Montreal.” He told me he had paid 9400€ for his.Sample Review Text
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv")!for row_text in reviews_file:! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
My friend said: �I cannot believe this is a Volvo! I had a car just like this when I lived in Montréal.� He told me he had paid 9400� for his.Output from UTF-8 encoded PSQL database
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
My friend said: “I cannot believe this is a Volvo! I had a car just like this when I lived in Montreal.” He told me he had paid 9400€ for his.Original CP-1252 Data
My friend said: “I cannot believe this is a Volvo! I had a car just like this when I lived in Montréal.” He told me he had paid 9400€ for his.Mixed CP-1252 & UTF-8
My friend said: �I cannot believe this is a Volvo! I had a car just like this when I lived in Montréal.� He told me he had paid 9400� for his.Interpreted as UTF-8 by database
Know your encodingsBest Practice #1
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: ! author, date, review_text = row_text.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: unicode_row = row_text.decode() author, date, review_text = unicode_row.split(",") converted_review = review_text.replace("Montreal", "Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: unicode_row = row_text.decode() author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u"Montreal", u"Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv")!for row_text in reviews_file: unicode_row = row_text.decode() author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u"Montreal", u"Montréal") DB.insert(ReviewTable, author, date, converted_review)
Traceback (most recent call last): File "...", line ..., in <module> unicode_row = row_text.decode() UnicodeDecodeError: 'ascii' codec can't decode byte 0x93 in position 31: ordinal not in range(128)
Traceback (most recent call last): File "...", line ..., in <module> unicode_row = row_text.decode() UnicodeDecodeError: 'ascii' codec can't decode byte 0x93 in position 31: ordinal not in range(128)
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: unicode_row = row_text.decode() author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u"Montreal", u"Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: unicode_row = row_text.decode() author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u"Montreal", u"Montréal") DB.insert(ReviewTable, author, date, converted_review)
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: unicode_row = row_text.decode("cp1252") author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u"Montreal", u"Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: unicode_row = row_text.decode("cp1252") author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u"Montreal", u"Montréal") DB.insert(ReviewTable, author, date, converted_review)
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: unicode_row = row_text.decode("cp1252") author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u"Montreal", u"Montréal") DB.insert(ReviewTable, author.encode("utf8"), date.encode("utf8"), converted_review.encode("utf8"))
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv")!for row_text in reviews_file: unicode_row = row_text.decode("cp1252") author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u"Montreal", u"Montréal") DB.insert(ReviewTable author.encode("utf8" date.encode("utf8"), converted_review.encode("utf8")
My friend said: “I cannot believe this is a Volvo! I had a car just like this when I lived in Montréal.” He told me he had paid 9400€ for his.
Use the Unicode SandwichBest Practice #2
Decode as early as possible.!Unicode everywhere in the middle.!Encode as late as possible.
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: unicode_row = row_text.decode("cp1252") author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u"Montreal", u"Montréal") DB.insert(ReviewTable, author.encode("utf8"), date.encode("utf8"), converted_review.encode("utf8"))
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: unicode_row = row_text.decode("cp1252") author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u"Montreal", u"Montréal") DB.insert(ReviewTable, author.encode("utf8"), date.encode("utf8"), converted_review.encode("utf8"))
[Python 2.7]
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv") !for row_text in reviews_file: unicode_row = row_text.decode("cp1252") author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u”Montreal", u"Montréal") DB.insert(ReviewTable, author.encode("utf8"), date.encode("utf8"), converted_review.encode("utf8"))
[Python 2.7]
Test Your (Text Related) CodeBest Practice #3
Test encoding ranges & boundaries
test_strings = ['Hello Montreal!', ,'ǝɥןןɐǝɹʇuoɯ oן¡' 'ђєɭɭ๏ ๓๏ภՇгєคɭ!'] !func_under_test(test_strings)
test_bytes = 'I am a bytestring mwahaha' !test_unicode = u'ι αм υηι¢σ∂є!' !!i_expect_unicode(test_bytes) !i_expect_bytes(test_unicode)
Test interfaces against both Python text types
def ascii_handling_function(ascii_str): ... ascii_str.decode('ascii') ...
Test handling of incorrect encoding
utf8_str = u'UՇF-8 ՇєsՇ'.encode('utf8') !with assertRaises(UnicodeDecodeError): line = ascii_handling_function(utf8_str)
Test handling of incorrect encoding
Best Practices1. Know your encodings
2. Use the Unicode sandwich
3. Test your (text related) code
Issues We Can’t Control
Incorrect encoding
Author Review
G. van Rossum If you decide to design your own car there are thousands sort of car…
R. Ebert Every great car should feel new every time you drive it.
L. Torvalds Volvo isn’t evil, they just make really crappy cars.
Application Processes Text
PSQL
Declared as “CP-1252”!
!
!
!
!
Is actually “UTF-8”
# -*- coding: utf-8 -*- !reviews_file = open("reviews_file.csv")!for row_text in reviews_file: unicode_row = row_text.decode("cp1252") author, date, review_text = unicode_row.split(u",") converted_review = review_text.replace(u"Montreal", u"Montréal") DB.insert(ReviewTable author.encode("utf8" date.encode("utf8"), converted_review.encode("utf8")
UnicodeDecodeError
How to Deal• Ask
How to Deal• Ask
• Guess (with chardet library)
How to Deal• Ask
• Guess (with chardet library)
• You wrote tests, right?
Mixed encodings or corrupted bytes
John Smith’s Autoplex !
Broken text… it’s fantastic! !
Hello ^[[30m; World
John Smith’s Autoplex!
Broken text… it’s fantastic!!
Hello ^[[30m; WorldMOJIBAKE
u"John Smith’s Autoplex"
u"John Smith’s Autoplex" !
>>>u'John Smith’sAutoplex'.encode('cp1252')
u"John Smith’s Autoplex" !
>>>u'John Smith’sAutoplex'.encode('cp1252') !'John Smith\xe2\x80\x99s Autoplex' (bytestring)
'John Smith\xe2\x80\x99s Autoplex' (bytestring)
'John Smith\xe2\x80\x99s Autoplex' (bytestring) !>>>'John Smith\xe2\x80\x99s Autoplex' \ .decode('utf8')
!!
u'John Smith’s Autoplex'
UTF8
U+2019 !’
UTF8
\xe2\x80\x99
U+2019 !’
UTF8
\xe2\x80\x99
U+2019 !’
U+00e2 !
â
U+20ac !€
U+2122 !
™
CP1252
str_dealer = u"John Smith’s Autoplex" !!def manually_convert_encoding(str_dealer): """ Manually replace incorrect, UTF8-encoded bytes with CP1252 bytes for the same character """ ! str_dealer.replace('\xe2\x80\x98', '\x91') # ‘ str_dealer.replace('\xe2\x80\x99', '\x92') # ’ str_dealer.replace('\xe2\x80\x9c', '\x93') # “ str_dealer.replace('\xe2\x80\x9d', '\x94') # ” str_dealer.replace('\xe2\x80\x94', '\x97') # — str_dealer.replace('\xe2\x84\xa2', '\x99') # ™ str_dealer.replace('\xe2\x82\xac', '\x80') # €
dealer_name = u"John Smith’s Autoplex" !>>> from ftfy import fix_text !>>> fix_text(dealer_name) !u"John Smith's Autoplex"
python-ftfy fixes mojibake
Target encoding can’t handle source data
Source Data
(UTF-8)
Target Application
Data (CP-1252)
?
>>>u'☃ Brrrr!'.encode('cp1252', 'strict') !Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/Users/esther/ENV/lib/python2.7/encodings/cp1252.py", line 12, in encode return codecs.charmap_encode(input,errors,encoding_table) UnicodeEncodeError: 'charmap' codec can't encode character u'\u2603' in position 0: character maps to <undefined>
[Python 2.7]
>>>u'☃ Brrrr!'.encode('cp1252', 'ignore') !' Brrrr!'
[Python 2.7]
>>>u'☃ Brrrr!'.encode('cp1252', 'replace') !'? Brrrr!'
[Python 2.7]
!!
U+0004
END OF TRANSMISSION
Cars.com / NewCars.com Tech Team !
SoCal Piggies !
Ned Batchelder (for his Pragmatic Unicode talk)
Thank you ツ
Pragmatic Unicode http://nedbatchelder.com/text/unipain.html !The Absolute Minimum You Must Know http://www.joelonsoftware.com/articles/Unicode.html !Chapter on Strings in “Dive into Python” by Mark Pilgrim http://getpython3.com/diveintopython3/strings.html !General questions, relating to UTF or Encoding Form http://www.unicode.org/faq/utf_bom.html !Unicode HOWTO (Python 2.7) http://docs.python.org/2/howto/unicode.html
The fundamentals
“Just what the dickens is ‘Unicode’?” https://pythonhosted.org/kitchen/unicode-frustrations.html
Differences between these commonly confused encodings http://www.i18nqa.com/debug/table-iso8859-1-vs-windows-1252.html !“Latin-1” in MySQL is more like “CP-1252” https://dev.mysql.com/doc/refman/5.0/en/charset-we-sets.html !Why it's important to write tests with character boundary values http://labs.spotify.com/2013/06/18/creative-usernames/
Further reading
chardet https://pypi.python.org/pypi/chardet !
python-ftfy https://github.com/LuminosoInsight/python-ftfy
Tools