Regexp: extract first occurrence of date in string

library(gsubfn)
strapply(txt, "(\\d{1,2}\\.\\d{1,2}\\.\\d{4}).*")[[1]]

strapply(txt, "(\\d{1,2}\\.\\d{1,2}\\.\\d{4}).*", ~ as.Date(x, "%m.%d.%Y"))[[1]]

strapply(txt, "\\d{1,2}\\.\\d{1,2}\\.\\d{4}")[[1]][1]

I would like to extract first date from a string:

txt <- "first date is 05.12.2009. Second date is 06.12.2009."
txt

[1] "first date is 05.12.2009. Second date is 06.12.2009."

I tried:

sub("^.*?\\s(\\d{1,2}\\.\\d{1,2}\\.\\d{4})", "\\1", txt, extended=T, perl=T)

[1] "05.12.2009. Second date is 06.12.2009."

How to modify this?

-J

Try this which uses a slightly simpler regexp:

library(gsubfn)
strapply(txt, "(\\d{1,2}\\.\\d{1,2}\\.\\d{4}).*")[[1]]

[1] "05.12.2009"

or we could convert it to Date class at the same time where we have
assumed month.day.year:

strapply(txt, "(\\d{1,2}\\.\\d{1,2}\\.\\d{4}).*", ~ as.Date(x, "%m.%d.%Y"))[[1]]

[1] "2009-05-12"

or this even simpler regexp extracting all the dates and then picking
off the first:

strapply(txt, "\\d{1,2}\\.\\d{1,2}\\.\\d{4}")[[1]][1]

[1] "05.12.2009"

On Sat, Jan 2, 2010 at 10:08 AM, johannes rara <johannesraja at gmail.com> wrote:

I would like to extract first date from a string:

txt <- "first date is 05.12.2009. Second date is 06.12.2009."
txt

[1] "first date is 05.12.2009. Second date is 06.12.2009."

I tried:

sub("^.*?\\s(\\d{1,2}\\.\\d{1,2}\\.\\d{4})", "\\1", txt, extended=T, perl=T)

[1] "05.12.2009. Second date is 06.12.2009."

How to modify this?

-J

Thanks, is the same possible using basic gsub/sub/grep etc. functions?

-J

2010/1/2 Gabor Grothendieck <ggrothendieck at gmail.com>:

Try this which uses a slightly simpler regexp:

library(gsubfn)
strapply(txt, "(\\d{1,2}\\.\\d{1,2}\\.\\d{4}).*")[[1]]

[1] "05.12.2009"

or we could convert it to Date class at the same time where we have
assumed month.day.year:

strapply(txt, "(\\d{1,2}\\.\\d{1,2}\\.\\d{4}).*", ~ as.Date(x, "%m.%d.%Y"))[[1]]

[1] "2009-05-12"

or this even simpler regexp extracting all the dates and then picking
off the first:

strapply(txt, "\\d{1,2}\\.\\d{1,2}\\.\\d{4}")[[1]][1]

[1] "05.12.2009"

On Sat, Jan 2, 2010 at 10:08 AM, johannes rara <johannesraja at gmail.com> wrote:

I would like to extract first date from a string:

txt <- "first date is 05.12.2009. Second date is 06.12.2009."
txt

[1] "first date is 05.12.2009. Second date is 06.12.2009."

I tried:

sub("^.*?\\s(\\d{1,2}\\.\\d{1,2}\\.\\d{4})", "\\1", txt, extended=T, perl=T)

[1] "05.12.2009. Second date is 06.12.2009."

How to modify this?

-J

txt <- "first date is 05.12.2009. Second date is 06.12.2009."
txt

l <- regexpr("\\d{1,2}\\.\\d{1,2}\\.\\d{4}", txt, perl=T)
substr(txt, l, l+9)

Use regexpr to get the offset into the string and its length and then
use substr to pick extract it.

On Sat, Jan 2, 2010 at 10:43 AM, johannes rara <johannesraja at gmail.com> wrote:

Thanks, is the same possible using basic gsub/sub/grep etc. functions?

-J

2010/1/2 Gabor Grothendieck <ggrothendieck at gmail.com>:

Try this which uses a slightly simpler regexp:

library(gsubfn)
strapply(txt, "(\\d{1,2}\\.\\d{1,2}\\.\\d{4}).*")[[1]]

[1] "05.12.2009"

or we could convert it to Date class at the same time where we have
assumed month.day.year:

strapply(txt, "(\\d{1,2}\\.\\d{1,2}\\.\\d{4}).*", ~ as.Date(x, "%m.%d.%Y"))[[1]]

[1] "2009-05-12"

or this even simpler regexp extracting all the dates and then picking
off the first:

strapply(txt, "\\d{1,2}\\.\\d{1,2}\\.\\d{4}")[[1]][1]

[1] "05.12.2009"

On Sat, Jan 2, 2010 at 10:08 AM, johannes rara <johannesraja at gmail.com> wrote:

I would like to extract first date from a string:

txt <- "first date is 05.12.2009. Second date is 06.12.2009."
txt

[1] "first date is 05.12.2009. Second date is 06.12.2009."

I tried:

sub("^.*?\\s(\\d{1,2}\\.\\d{1,2}\\.\\d{4})", "\\1", txt, extended=T, perl=T)

[1] "05.12.2009. Second date is 06.12.2009."

How to modify this?

-J