Reading a UTF8 CSV file with Python

Question

I am trying to read a CSV file with accented characters with Python (only French and/or Spanish characters). Based on the Python 2.5 documentation for the csvreader (http://docs.python.org/library/csv.html), I came up with the following code to read the CSV file since the csvreader supports only ASCII.

def unicode_csv_reader(unicode_csv_data, dialect=csv.excel, **kwargs):     # csv.py doesn't do Unicode; encode temporarily as UTF-8:     csv_reader = csv.reader(utf_8_encoder(unicode_csv_data),                             dialect=dialect, **kwargs)     for row in csv_reader:         # decode UTF-8 back to Unicode, cell by cell:         yield [unicode(cell, 'utf-8') for cell in row]  def utf_8_encoder(unicode_csv_data):     for line in unicode_csv_data:         yield line.encode('utf-8')  filename = 'output.csv' reader = unicode_csv_reader(open(filename)) try:     products = []     for field1, field2, field3 in reader:         ... 

Below is an extract of the CSV file I am trying to read:

0665000FS10120684,SD1200IS,Appareil photo numérique PowerShot de 10 Mpx de Canon avec trépied (SD1200IS) - Bleu 0665000FS10120689,SD1200IS,Appareil photo numérique PowerShot de 10 Mpx de Canon avec trépied (SD1200IS) - Gris 0665000FS10120687,SD1200IS,Appareil photo numérique PowerShot de 10 Mpx de Canon avec trépied (SD1200IS) - Vert ... 

Even though I try to encode/decode to UTF-8, I am still getting the following exception:

Traceback (most recent call last):   File ".\Test.py", line 53, in <module>     for field1, field2, field3 in reader:   File ".\Test.py", line 40, in unicode_csv_reader     for row in csv_reader:   File ".\Test.py", line 46, in utf_8_encoder     yield line.encode('utf-8', 'ignore') UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 68: ordinal not in range(128) 

How do I fix this?

Answer 1

The .encode method gets applied to a Unicode string to make a byte-string; but you're calling it on a byte-string instead... the wrong way 'round! Look at the codecs module in the standard library and codecs.open in particular for better general solutions for reading UTF-8 encoded text files. However, for the csv module in particular, you need to pass in utf-8 data, and that's what you're already getting, so your code can be much simpler:

import csv  def unicode_csv_reader(utf8_data, dialect=csv.excel, **kwargs):     csv_reader = csv.reader(utf8_data, dialect=dialect, **kwargs)     for row in csv_reader:         yield [unicode(cell, 'utf-8') for cell in row]  filename = 'da.csv' reader = unicode_csv_reader(open(filename)) for field1, field2, field3 in reader:   print field1, field2, field3  

PS: if it turns out that your input data is NOT in utf-8, but e.g. in ISO-8859-1, then you do need a "transcoding" (if you're keen on using utf-8 at the csv module level), of the form line.decode('whateverweirdcodec').encode('utf-8') -- but probably you can just use the name of your existing encoding in the yield line in my code above, instead of 'utf-8', as csv is actually going to be just fine with ISO-8859-* encoded bytestrings.

Answer 2

Python 2.X

There is a unicode-csv library which should solve your problems, with added benefit of not naving to write any new csv-related code.

Here is a example from their readme:

>>> import unicodecsv >>> from cStringIO import StringIO >>> f = StringIO() >>> w = unicodecsv.writer(f, encoding='utf-8') >>> w.writerow((u'é', u'ñ')) >>> f.seek(0) >>> r = unicodecsv.reader(f, encoding='utf-8') >>> row = r.next() >>> print row[0], row[1] é ñ 

Python 3.X

In python 3 this is supported out of the box by the build-in csv module. See this example:

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