I have imported a data frame that looks like this:
Measurement.Date.and.Time Z.Average..nm. PDI
572 Dienstag, 22. M?rz 2005 11:05:59 366,4 0,468
573 Dienstag, 22. M?rz 2005 11:09:30 353,4 0,532
574 Dienstag, 22. M?rz 2005 11:12:59 343 0,428
575 Dienstag, 22. M?rz 2005 11:16:28 354,1 0,433
576 Dienstag, 22. M?rz 2005 11:19:59 341,9 0,349
577 Dienstag, 22. M?rz 2005 11:23:29 334,9 0,429
...
Would there be a way to extract the time in numerical form from the
Measurement.Date.and.Time field? What I would like to do is a time
series where, for example,
Dienstag, 22. M?rz 2005 11:05:59 is time=0 min
Dienstag, 22. M?rz 2005 11:09:30 is time=3.5 min, etc.
Thank you in advance for your help.
Luis
Luis Tercero <luis.tercero <at> ebi-wasser.uni-karlsruhe.de> writes:
:
: I have imported a data frame that looks like this:
:
: Measurement.Date.and.Time Z.Average..nm. PDI
: 572 Dienstag, 22. M?rz 2005 11:05:59 366,4 0,468
: 573 Dienstag, 22. M?rz 2005 11:09:30 353,4 0,532
: 574 Dienstag, 22. M?rz 2005 11:12:59 343 0,428
: 575 Dienstag, 22. M?rz 2005 11:16:28 354,1 0,433
: 576 Dienstag, 22. M?rz 2005 11:19:59 341,9 0,349
: 577 Dienstag, 22. M?rz 2005 11:23:29 334,9 0,429
: ...
:
: Would there be a way to extract the time in numerical form from the
: Measurement.Date.and.Time field? What I would like to do is a time
: series where, for example,
: Dienstag, 22. M?rz 2005 11:05:59 is time=0 min
: Dienstag, 22. M?rz 2005 11:09:30 is time=3.5 min, etc.
:
: Thank you in advance for your help.
:
: Luis
Make sure that you are in a German locale:
# this works on Windows XP. On other OS, "ge" code may differ.
Sys.setlocale("LC_TIME", "ge")
Then if DF is your data frame use strptime (see ?strptime for more
on the % codes):
dat <- strptime(DF[,1], "%A, %d. %B %Y %H:%M:%S")
dat - dat[1] # difference in time since the first date time
Gabor Grothendieck <ggrothendieck <at> myway.com> writes:> > Luis Tercero <luis.tercero <at> ebi-wasser.uni-karlsruhe.de> writes: > > : > : I have imported a data frame that looks like this: > : > : Measurement.Date.and.Time Z.Average..nm. PDI > : 572 Dienstag, 22. M?rz 2005 11:05:59 366,4 0,468 > : 573 Dienstag, 22. M?rz 2005 11:09:30 353,4 0,532 > : 574 Dienstag, 22. M?rz 2005 11:12:59 343 0,428 > : 575 Dienstag, 22. M?rz 2005 11:16:28 354,1 0,433 > : 576 Dienstag, 22. M?rz 2005 11:19:59 341,9 0,349 > : 577 Dienstag, 22. M?rz 2005 11:23:29 334,9 0,429 > : ... > : > : Would there be a way to extract the time in numerical form from the > : Measurement.Date.and.Time field? What I would like to do is a time > : series where, for example, > : Dienstag, 22. M?rz 2005 11:05:59 is time=0 min > : Dienstag, 22. M?rz 2005 11:09:30 is time=3.5 min, etc. > : > : Thank you in advance for your help. > : > : Luis > > Make sure that you are in a German locale: > > # this works on Windows XP. On other OS, "ge" code may differ. > Sys.setlocale("LC_TIME", "ge") > > Then if DF is your data frame use strptime (see ?strptime for more > on the % codes): > > dat <- strptime(DF[,1], "%A, %d. %B %Y %H:%M:%S") > dat - dat[1] # difference in time since the first date timeOne other comment. I assumed your data time field is stored as character in the data frame. If its stored as a factor then you need to convert it to character first using as.character. If its already stored as a POSIXct date time then all you have to do is subtract off the first one. (Note that if you put the output of dput(DF) in your post then people will be able to exactly recreate your data frame and then know what you have.) Also, RNews 4/1 has a table with lots of date time processing idioms.
I have imported a data frame that looks like this:
Measurement.Date.and.Time Z.Average..nm. PDI
572 Dienstag, 22. M?rz 2005 11:05:59 366,4 0,468
573 Dienstag, 22. M?rz 2005 11:09:30 353,4 0,532
574 Dienstag, 22. M?rz 2005 11:12:59 343 0,428
575 Dienstag, 22. M?rz 2005 11:16:28 354,1 0,433
576 Dienstag, 22. M?rz 2005 11:19:59 341,9 0,349
577 Dienstag, 22. M?rz 2005 11:23:29 334,9 0,429
...
Would there be a way to extract the time in numerical form from the
Measurement.Date.and.Time field? What I would like to do is a time
series where, for example,
Dienstag, 22. M?rz 2005 11:05:59 is time=0 min
Dienstag, 22. M?rz 2005 11:09:30 is time=3.5 min, etc.
Thank you in advance for your help.
Luis