Re: [R] regular expression in gsub() for strings with leading backslash
That works like a charm! Thanks so much Duncan.
On Fri, Apr 29, 2011 at 6:37 PM, Duncan Murdoch wrote:
> On 29/04/2011 9:34 PM, Miao wrote:
>
>> Thanks Duncan for clarifying this. I'm pretty a newbie to such type of
>> characters and special characters. In R's gsub() what regular
>> expressions shall I use to handle all these situations?
>>
>
> I don't know. This might work:
>
> gsub("[\x01-\x1f\x7f-\xff]", "", x)
>
> (i.e. the range from character 1 to character 31, and 127 to 255) but I
> don't know if our regular expression matcher will accept those characters.
>
> Duncan Murdoch
>
>
>>
>> On Fri, Apr 29, 2011 at 6:07 PM, Duncan Murdoch
>> mailto:murdoch.dun...@gmail.com>> wrote:
>>
>>On 29/04/2011 7:41 PM, Miao wrote:
>>
>>Hello,
>>
>>Can anyone help on gsub() in R? I have a string like something
>>below, and
>>wanted to delete all the strings with leading backslash,
>>including "\xa0On",
>>"\023, "\xab", and many others. How should I write a regular
>>expression
>>pattern in gsub()? I don't care how many characters following
>>backslash.
>>
>>
>>
>>If those are R strings, none of them contain a backslash. In R, a
>>backslash would always be printed as \\.
>>
>>\x is the introduction to a hexadecimal encoding for a character;
>>the next two characters show the hex digits. So your first string
>>contains a single character \xa0, the third one contains \xab, and
>>so on.
>>
>>The \023 is an octal encoding for a single character.
>>
>>Duncan Murdoch
>>
>>
>>
>>txt<- "Is This Thing\xa0On? http://bit.ly/jAbKem wait \023 for
>>people \xab
>>and be patient :"
>>
>>Thanks in advance,
>>Miao
>>
>>[[alternative HTML version deleted]]
>>
>>__
>>R-help@r-project.org mailing list
>>
>>https://stat.ethz.ch/mailman/listinfo/r-help
>>PLEASE do read the posting guide
>>http://www.R-project.org/posting-guide.html
>>and provide commented, minimal, self-contained, reproducible code.
>>
>>
>>
>>
>>
>> --
>> proceed everyday
>>
>
>
--
proceed everyday
[[alternative HTML version deleted]]
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Re: [R] regular expression in gsub() for strings with leading backslash
On Fri, 29 Apr 2011, Duncan Murdoch wrote:
On 29/04/2011 7:41 PM, Miao wrote:
Can anyone help on gsub() in R? I have a string like something below, and
wanted to delete all the strings with leading backslash, including
"\xa0On",
"\023, "\xab", and many others. How should I write a regular expression
pattern in gsub()? I don't care how many characters following backslash.
If those are R strings, none of them contain a backslash. In R, a backslash
would always be printed as \\.
\x is the introduction to a hexadecimal encoding for a character; the next
two characters show the hex digits. So your first string contains a single
character \xa0, the third one contains \xab, and so on.
The \023 is an octal encoding for a single character.
If we were dealing with a leading backslash, I guess this would do it:
gsub("^.*", "", txt)
R would display a double backslash, but I believe that represents a single
backslash. So if the string were saved using write.table, say, only a
single backslash would be stored.
a <- "\\This is a string."
a
[1] "\\This is a string."
gsub("^", "", a)
[1] "This is a string."
a
[1] "\\This is a string."
gsub("^.*", "", a)
[1] ""
gsub("^.*", "", c(a,"Another string","\\more"))
[1] "" "Another string" ""
write.table(a, file="a.txt", quote=F, row.names=F, col.names=F)
$ cat a.txt
\This is a string.
Apparently this is not what the OP really wanted. The OP probably wanted
to remove characters that were not from the regular ASCII set.
Mike
--
Michael B. Miller, Ph.D.
Minnesota Center for Twin and Family Research
Department of Psychology
University of Minnesota
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] regular expression in gsub() for strings with leading backslash
On 29/04/2011 9:34 PM, Miao wrote:
Thanks Duncan for clarifying this. I'm pretty a newbie to such type of
characters and special characters. In R's gsub() what regular
expressions shall I use to handle all these situations?
I don't know. This might work:
gsub("[\x01-\x1f\x7f-\xff]", "", x)
(i.e. the range from character 1 to character 31, and 127 to 255) but I
don't know if our regular expression matcher will accept those characters.
Duncan Murdoch
On Fri, Apr 29, 2011 at 6:07 PM, Duncan Murdoch
mailto:murdoch.dun...@gmail.com>> wrote:
On 29/04/2011 7:41 PM, Miao wrote:
Hello,
Can anyone help on gsub() in R? I have a string like something
below, and
wanted to delete all the strings with leading backslash,
including "\xa0On",
"\023, "\xab", and many others. How should I write a regular
expression
pattern in gsub()? I don't care how many characters following
backslash.
If those are R strings, none of them contain a backslash. In R, a
backslash would always be printed as \\.
\x is the introduction to a hexadecimal encoding for a character;
the next two characters show the hex digits. So your first string
contains a single character \xa0, the third one contains \xab, and
so on.
The \023 is an octal encoding for a single character.
Duncan Murdoch
txt<- "Is This Thing\xa0On? http://bit.ly/jAbKem wait \023 for
people \xab
and be patient :"
Thanks in advance,
Miao
[[alternative HTML version deleted]]
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
--
proceed everyday
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] regular expression in gsub() for strings with leading backslash
Thanks Duncan for clarifying this. I'm pretty a newbie to such type of characters and special characters. In R's gsub() what regular expressions shall I use to handle all these situations? On Fri, Apr 29, 2011 at 6:07 PM, Duncan Murdoch wrote: > On 29/04/2011 7:41 PM, Miao wrote: > >> Hello, >> >> Can anyone help on gsub() in R? I have a string like something below, and >> wanted to delete all the strings with leading backslash, including >> "\xa0On", >> "\023, "\xab", and many others. How should I write a regular expression >> pattern in gsub()? I don't care how many characters following backslash. >> > > > If those are R strings, none of them contain a backslash. In R, a > backslash would always be printed as \\. > > \x is the introduction to a hexadecimal encoding for a character; the next > two characters show the hex digits. So your first string contains a single > character \xa0, the third one contains \xab, and so on. > > The \023 is an octal encoding for a single character. > > Duncan Murdoch > > > >> txt<- "Is This Thing\xa0On? http://bit.ly/jAbKem wait \023 for people >> \xab >> and be patient :" >> >> Thanks in advance, >> Miao >> >>[[alternative HTML version deleted]] >> >> __ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > > -- proceed everyday [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] regular expression in gsub() for strings with leading backslash
On 29/04/2011 7:41 PM, Miao wrote: Hello, Can anyone help on gsub() in R? I have a string like something below, and wanted to delete all the strings with leading backslash, including "\xa0On", "\023, "\xab", and many others. How should I write a regular expression pattern in gsub()? I don't care how many characters following backslash. If those are R strings, none of them contain a backslash. In R, a backslash would always be printed as \\. \x is the introduction to a hexadecimal encoding for a character; the next two characters show the hex digits. So your first string contains a single character \xa0, the third one contains \xab, and so on. The \023 is an octal encoding for a single character. Duncan Murdoch txt<- "Is This Thing\xa0On? http://bit.ly/jAbKem wait \023 for people \xab and be patient :" Thanks in advance, Miao [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
