Subset()
Hi Elise,
If I create a CSV file like your example and read it into a data frame:
eldf<-read.csv("el.csv")
Then convert the first field to POSIXt dates:
eldf$DateTime<-strptime(eldf$DateTime,"%Y-%m-%d %H:%M:%S")
class(eldf$DateTime)
[1] "POSIXlt" "POSIXt"
I can subset the file like this:
time_after<-strptime("2017-01-09 18:00:00","%Y-%m-%d %H:%M:%S")
time_after
[1] "2017-01-09 18:00:00 AEDT"
eldf[eldf$DateTime >= time_after,]
DateTime RECORD PTemp PPFD_Avg Air_Temp_Avg RH_avg Soil_Temp 7 2017-01-09 18:00:00 6 21.26 -48.83 -38.49 -0.415 79 8 2017-01-09 18:15:00 7 21.21 -52.23 -39.00 -0.642 79 9 2017-01-09 18:30:00 8 21.12 -54.68 -39.41 -0.805 79 10 2017-01-09 18:45:00 9 21.04 -56.44 .39.74 -0.939 79 11 2017-01-09 19:00:00 10 20.99 -57.71 -40.01 -1.046 79 12 2017-01-09 19:15:00 11 20.91 -58.66 -40.25 -1.137 79 13 2017-01-09 19:30:00 12 21.83 -59.39 -40.46 -1.208 79 Perhaps this will do what you want. No need to apologize for your English, I could not make myself understood in French. Jim On Sun, Jan 22, 2017 at 4:15 AM, Elise LIKILIKI
<elise.likiliki at gmail.com> wrote:
Hi Jim, Yes exactly it returns "POSIXct" "POSIXt" Find attached a screenshot showing my data in "data" object. I don't need the data before 2017-01-10 11:00:00 nor columns : Records and Ptemp. I've tried with subset() and with [ ] but I still have some rows containing data before 2017-01-10 11:00:00. I'm french so I am really sorry about my english 2017-01-21 11:41 GMT+01:00 Jim Lemon <drjimlemon at gmail.com>:
Hi Elise,. I would ask: class(data$DateTime) and see if it returns: "POSIXct" "POSIXt" Jim On Sat, Jan 21, 2017 at 3:02 AM, Elise LIKILIKI <elise.likiliki at gmail.com> wrote:
Hello, I have a dataset containing Date Time, Air Temperature, PPFD, Sol Temperature... The first data are false so I would like to extract the other ones. I've tried :
data1<-subset(data,DateTime>=as.POSIXct("2017-01-10
11:00:00",format="%Y-%m-%d
%H:%M:%S"),select=c(DateTime,PPFD_Avg,Air_Temp_Avg,RH_Avg,Soil_Temp_Avg))
But I still have 4 rows with data from 2017-01-10 10:00:00 to 2017-01-10
10:45:00 and I don't understand why.
Does anyone could help me please.
Thanks,
Elise LIKILIKI
[[alternative HTML version deleted]]
______________________________________________ R-help at 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.