[Tutor] Removing control characters

[Dinesh B Vadhia]

Okay, here is a combination of Mark's suggestions and yours:

> # string of all chars
> a = ''.join([chr(n) for n in range(256)])
> a
'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff'

> # string of wanted chars
> b = ''.join([n for n in a if ord(n) >= 32 and ord(n) <= 126])
> b
' !"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~'

> # string of unwanted chars > ord(126)
> c = ''.join([n for n in a if ord(n) < 32 or ord(n) > 126])
> c
'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff'

> # the string to process
> s = "Product Concepts\xe2\x80\x94Hard candy with an innovative twist, Internet Archive: Wayback Machine. [online] Mar. 25, 2004. Retrieved from the Internet <URL: http://www.confectionery-innovations.com>."

> # replace unwanted chars in string s with " "
> t = "".join([(" " if n in c else n) for n in s if n not in c])
> t
'Product ConceptsHard candy with an innovative twist, Internet Archive: Wayback Machine. [online] Mar. 25, 2004. Retrieved from the Internet <URL: http://www.confectionery-innovations.com>.'

This last bit doesn't work ie. replacing the unwanted chars with " " - eg. 'ConceptsHard'.  What's missing?

Dinesh



From: Kent Johnson 
Sent: Thursday, February 19, 2009 12:36 PM
To: Dinesh B Vadhia 
Cc: tutor at python.org 
Subject: Re: [Tutor] Removing control characters


On Thu, Feb 19, 2009 at 2:25 PM, Dinesh B Vadhia
<dineshbvadhia at hotmail.com> wrote:

> # 3) Replacing a set of characters with a single character ie.
>
> for c in str:
>     if c in set:
>         string.replace (c, r)
>
> to give
>
>> 'Chris Perkins : $$$-$$$$'
> My solution is:
>
> print ''.join[string.replace(c, r) for c in str if c in set]

With the syntax corrected this will not do what you want; the "if c in
set" filters the characters in the result, so the result will contain
only the replacement characters. You would need something like
''.join([ (r if c in set else c) for c in str])

Note that both 'set' and 'str' are built-in names and therefore poor
choices for variable names.

Kent
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