[R] grep pattern

[jim holtman]

try this using strsplit:

> x <- round(runif(10)*100000, digits=0)
> y <- as.Date(x, origin="1970-01-01")
> str(y)
Class 'Date'  num [1:10] 26551 37212 57285 90821 20168 ...
> y1 <- as.character(y)
> str(y1)
 chr [1:10] "2042-09-11" "2071-11-19" "2126-11-04" "2218-08-30"
"2025-03-21" "2215-12-22" ...
> x <- strsplit(y1, '-')
> x[1:3]
[[1]]
[1] "2042" "09"   "11"

[[2]]
[1] "2071" "11"   "19"

[[3]]
[1] "2126" "11"   "04"

> x.1 <- sapply(x, '[', 3)
> str(x.1)
 chr [1:10] "11" "19" "04" "30" "21" "22" "24" "03" "31" "02"
>


On Tue, May 24, 2011 at 10:19 AM, Kang Min <ngokangmin at gmail.com> wrote:
> I have another question -
>
> I'd like to extract dates from a vector of yyyy-mm-dd, so I just want
> the dd.
>
> x <- round(runif(10)*100000, digits=0)
> y <- as.Date(x, origin="1970-01-01")
>
> I tried this based on the code that Jim provided, but it just printed
> the whole date. I think I just need to tweak it a little, but haven't
> been able to figure it out.
>
> y[grep("[[:digit:]]{2}$", y)]
>
> Thanks.
> Kang Min
>
> On May 23, 7:22 am, jim holtman <jholt... at gmail.com> wrote:
>> If you want to only match names of length 6, you will have to use thispattern:
>>
>> > x <- c("ZFHSJK", "ZFHJKZ","ZIOPWE","ZLKJSD","ZKFLPZ", "ZAAAAAAZ", "ZAZ",
>>
>> +     "ZAAAAZAZ", "ZRITEZ")
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> > # match exactly values of length 6
>> > len6 <- "^Z[[:alpha:]]{4}Z$"
>> >grep(len6, x)
>> [1] 2 5 9
>>
>> On Sun, May 22, 2011 at 5:10 PM, Kang Min <ngokang... at gmail.com> wrote:
>> > Thanks!
>>
>> > On May 21, 7:09 am, David Winsemius <dwinsem... at comcast.net> wrote:
>> >> On May 20, 2011, at 11:57 AM, Kang Min wrote:
>>
>> >> > Hi all,
>>
>> >> > I'm trying to subset apatternin a vector. Each argument has 6
>> >> > letters, and I need those that start with Z and end with Z.
>>
>> >> > e.g.
>> >> > x <- c("ZFHSJK", "ZFHJKZ","ZIOPWE","ZLKJSD","ZKFLPZ")
>>
>> >> > I've looked up other discussions but still can't seem to find the
>> >> > answer.
>>
>> >> You may need to study the regex page a bit longer
>>
>> >> the "^" is the beginning of a string
>> >> ".+" will math can arbitrarily long string of anything
>> >> and "$" indicates the end of a string
>>
>> >>  > x <- c("ZFHSJK", "ZFHJKZ","ZIOPWE","ZLKJSD","ZKFLPZ")
>> >>  >grep("^Z.+Z$", x)
>> >> [1] 2 5
>> >>  >grep("^Z.+Z$", x, value=TRUE)
>> >> [1] "ZFHJKZ" "ZKFLPZ"
>>
>> >> > Thanks.
>> >> > Kangmin
>>
>> >> > ______________________________________________
>> >> > R-h... at r-project.org mailing list
>> >> >https://stat.ethz.ch/mailman/listinfo/r-help
>> >> > PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html
>> >> > and provide commented, minimal, self-contained, reproducible code.
>>
>> >> David Winsemius, MD
>> >> West Hartford, CT
>>
>> >> ______________________________________________
>> >> R-h... at r-project.org mailing listhttps://stat.ethz.ch/mailman/listinfo/r-help
>> >> PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html
>> >> and provide commented, minimal, self-contained, reproducible code.
>>
>> > ______________________________________________
>> > R-h... at r-project.org mailing list
>> >https://stat.ethz.ch/mailman/listinfo/r-help
>> > PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html
>> > and provide commented, minimal, self-contained, reproducible code.
>>
>> --
>> Jim Holtman
>> Data Munger Guru
>>
>> What is the problem that you are trying to solve?
>>
>> ______________________________________________
>> R-h... at r-project.org mailing listhttps://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help at 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.
>



-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?