Python: Regex and String Length in byte

Question

I am writing a program in python and have some question (I am 100% new to python):

import re

rawData = '7I+8I-7I-9I-8I-'

print len(rawData)

rawData = re.sub("[0-9]I\+","",rawData)
rawData = re.sub("[0-9]I\-","",rawData)

print rawData

How to merge the 2 regex into one using |? It means it will get rid of both 9I- and 9I+ using just one regex operation.
Does len(rawData) return the length of rawData is byte?

Thank you.

In Python 2.x rawData would be just some bytes but in Python 3 it would be Unicode text. — Facundo Casco
– Facundo Casco, Commented Jul 1, 2011 at 16:14

Facundo Casco · Accepted Answer · 2011-07-01 17:18:37Z

5

See the difference:

$ python3
Python 3.1.3 (r313:86834, May 20 2011, 06:10:42) 
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> len('día')   # Unicode text
3
>>> 

$ python
Python 2.7.1 (r271:86832, May 20 2011, 17:19:04) 
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> len('día')   # bytes
4
>>> len(u'día')  # Unicode text
3
>>>


Python 3.1.3 (r313:86834, May 20 2011, 06:10:42) 
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> len(b'día')
  File "<stdin>", line 1
SyntaxError: bytes can only contain ASCII literal characters.
>>> len(b'dia')
3
>>>

edited Jul 1, 2011 at 17:18

answered Jul 1, 2011 at 16:19

Facundo Casco

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3 Comments

Tu Hoang Over a year ago

Wow. I never knew that :( I am using python 2.6.5 on the server.

Tu Hoang Over a year ago

Then how do you get len in bytes in python 3? Is there an universal way of getting the length in bytes of a string in both python 2 and python 3?

Facundo Casco Over a year ago

In Python 3, if you want bytes you must use b'bytes'

Fitoria · Accepted Answer · 2011-07-01 15:58:36Z

0

Why don't you take a different approach. With replace method?

answered Jul 1, 2011 at 15:58

Fitoria

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Comments

cwallenpoole · Accepted Answer · 2011-07-01 16:47:23Z

0

len refers to the number of characters when applied to a unicode string (this is nuanced, other answers flush that out more), bytes in a encoded string, items in a list (or set, or keys in a dictionary)...

rawData = re.sub("[0-9]I(\+|-)","",rawData)

edited Jul 1, 2011 at 16:47

answered Jul 1, 2011 at 15:55

cwallenpoole

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1 Comment

cwallenpoole Over a year ago

@MRAB I've read it. as F.C. put it len('día') is 3 in Python 3 is 3, while it is 4 in Python 2.x. I use Python 3 primarily. "encoded" did nor refer to unicode (used the wrong word there), I was referring to strings such as: '\x03'. While that may appear to have a length of 4, that only has a len of 1 (as it is only one character when printed)

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