This is normal. R is a (mostly) functional language, which means functions normally don't have side effects like changing input data.
Try saving the result of your function calls in a new object. -- Sent from my phone. Please excuse my brevity. On June 21, 2016 3:57:54 PM PDT, Alice Domalik <9a...@queensu.ca> wrote: >Hi List, > > >I'm working with some bird GPS tracking data, and I would like to >exclude points based on the time stamp. > >Some background information- the GPS loggers track each bird for just >over 24 hours, starting in the evening, and continuing through the >night and the following day. What I would like to do is exclude points >taken after 21:30 on the day AFTER deployment (but retain points >between 21:30 and 23:59 on the day of deployment). > >My data is set up like this: > >birdID x y datetime >15K11 492719.9 5634805 2015-06-23 18:25:00 > >I've tried running the code posted below. >The idea is to use the function "mutate" to create a new variable >called newdate that takes the earliest observation for each bird and >sets the date for cutoff as the next day at 21:30:00. > >library(dplyr); library(lubridate) > >df %>% > group_by(birdID) %>% >mutate(newdate=as.POSIXct(date(min(datetime)) + days(1) + hours(21) + >minutes(30))) %>% > filter(datetime<newdate) > >R runs the code, but it doesn't actually change the data frame. I've >double checked that "datetime" is POSIXct. I've also tried running the >code without the the last line to check if R will at least create the >new column "newdate", but it doesn't. >Any insight into why my code isn't working? > > [[alternative HTML version deleted]] > >______________________________________________ >R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >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 -- To UNSUBSCRIBE and more, see 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.
