Marna Wagley
2021-Apr-22 23:45 UTC
[R] Conditional extraction of values in a data.frame in r
Hi R Users,
I have been struggling to extract the data based on conditional values in
different columns. I have a very big dataset (rows) and a couple of
columns. here an example of the dataset is:
daT<-structure(list(ID = c("id1", "id2", "id3",
"id4", "id5", "id6",
"id7"), First_detectiondate = c("7/21/2015",
"5/19/2015", "5/27/2015",
NA, "9/25/2015", NA, NA), Second_detectiondate = c(NA, NA,
"6/1/2015",
"5/29/2015", NA, NA, "4/17/2015"), third_detectiondate =
c(NA,
"5/21/2015", "6/20/2015", NA, NA, "", NA)), class
= "data.frame", row.names
= c(NA,
-7L))
head(daT)
I wanted to put conditions such as: if any of the columns of 2.3.4 has a
date, get the date which was latest. If there is no date, put NA. and I was
looking for the output as shown in the following table.
output<-structure(list(ID = c("id1", "id2",
"id3", "id4", "id5", "id6",
"id7"), First_detectiondate = c("7/21/2015",
"5/19/2015", "5/27/2015",
NA, "9/25/2015", NA, NA), Second_detectiondate = c(NA, NA,
"6/1/2015",
"5/29/2015", NA, NA, "4/17/2015"), third_detectiondate =
c(NA,
"5/21/2015", "6/20/2015", NA, NA, "", NA), output1
= c("7/21/2015",
"5/21/2015", "6/20/2015", "5/29/2015",
"9/25/2015", NA, "4/17/2015"
)), class = "data.frame", row.names = c(NA, -7L))
head(output)
Is there a way to get the table similar to the table "output"?
Thank you very much for your help.
Sincerely,
MW
[[alternative HTML version deleted]]
Hi Marna,
This may be what you want:
get_latest<-function(x,format="%m/%d/%Y") {
x<-unlist(x)
x[nchar(x)==0]<-NA
if(all(is.na(x))) return(NA)
else return(format(max(as.Date(x,format),na.rm=TRUE),format))
}
daT$output1<-apply(daT[,2:4],1,get_latest)
The empty value in daT gave a bit of trouble. I have written it to
accept and return character dates.
Jim
On Fri, Apr 23, 2021 at 9:46 AM Marna Wagley <marna.wagley at gmail.com>
wrote:>
> Hi R Users,
> I have been struggling to extract the data based on conditional values in
> different columns. I have a very big dataset (rows) and a couple of
> columns. here an example of the dataset is:
>
> daT<-structure(list(ID = c("id1", "id2",
"id3", "id4", "id5", "id6",
>
> "id7"), First_detectiondate = c("7/21/2015",
"5/19/2015", "5/27/2015",
>
> NA, "9/25/2015", NA, NA), Second_detectiondate = c(NA, NA,
"6/1/2015",
>
> "5/29/2015", NA, NA, "4/17/2015"), third_detectiondate
= c(NA,
>
> "5/21/2015", "6/20/2015", NA, NA, "", NA)),
class = "data.frame", row.names
> = c(NA,
>
> -7L))
>
>
> head(daT)
>
>
> I wanted to put conditions such as: if any of the columns of 2.3.4 has a
> date, get the date which was latest. If there is no date, put NA. and I was
> looking for the output as shown in the following table.
>
>
> output<-structure(list(ID = c("id1", "id2",
"id3", "id4", "id5", "id6",
>
> "id7"), First_detectiondate = c("7/21/2015",
"5/19/2015", "5/27/2015",
>
> NA, "9/25/2015", NA, NA), Second_detectiondate = c(NA, NA,
"6/1/2015",
>
> "5/29/2015", NA, NA, "4/17/2015"), third_detectiondate
= c(NA,
>
> "5/21/2015", "6/20/2015", NA, NA, "", NA),
output1 = c("7/21/2015",
>
> "5/21/2015", "6/20/2015", "5/29/2015",
"9/25/2015", NA, "4/17/2015"
>
> )), class = "data.frame", row.names = c(NA, -7L))
>
> head(output)
>
>
>
> Is there a way to get the table similar to the table "output"?
>
>
> Thank you very much for your help.
>
>
> Sincerely,
>
>
> MW
>
> [[alternative HTML version deleted]]
>
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