R help - Jun 2022 - Build a data.table via two string lists

Hello everyone,

I have the following two structures:

# str(cl)
# chr [1:5] "timestamp" "assess" "catheter"
"service" "ref"

# str(rw)
# chr [1:5] "1654508112" "3" "gel"
"2785" ?16545081121a8d8f956cb871053a3f56b782b70a76"

From which I would like to generate a 5 col x 1 row data.table; the question is
?how??

?cl? represents the column names; ?rw? the row values.

With anticipatory thanks ?
John

You could turn your row values in a list, attach names to that list, and
pass the list to data.frame():
> cl <- c("timestamp", "assess", "catheter",
"service", "ref")
> rw <- c("1654508112", "3", "gel",
"2785",
"16545081121a8d8f956cb871053a3f56b782b70a76")
> df <- data.frame(setNames(as.list(rw), nm=cl))
> df
   timestamp assess catheter service
 ref
1 1654508112      3      gel    2785
16545081121a8d8f956cb871053a3f56b782b70a76

At this point all the columns have type "character".  You may want to
convert some columns to more meaningful types, e.g., "timestamp" to a
date/time class and "assess" to a number. 
E.g.,
> df[["timestamp"]] <-
as.POSIXct(as.numeric(df[["timestamp"]]),
origin=as.POSIXct("1970/01/01"))
> df[["assess"]] <- as.numeric(df[["assess"]])
> df
            timestamp assess catheter service
         ref
1 2022-06-06 10:35:12      3      gel    2785
16545081121a8d8f956cb871053a3f56b782b70a76
> str(df)
'data.frame':   1 obs. of  5 variables:
 $ timestamp: POSIXct, format: "2022-06-06 10:35:12"
 $ assess   : num 3
 $ catheter : chr "gel"
 $ service  : chr "2785"
 $ ref      : chr "16545081121a8d8f956cb871053a3f56b782b70a76"

-Bill


On Mon, Jun 6, 2022 at 9:51 AM John RF Staples via R-help <
r-help at r-project.org> wrote:
> Hello everyone,
>
> I have the following two structures:
>
> # str(cl)
> # chr [1:5] "timestamp" "assess" "catheter"
"service" "ref"
>
> # str(rw)
> # chr [1:5] "1654508112" "3" "gel"
"2785"
> ?16545081121a8d8f956cb871053a3f56b782b70a76"
>
> From which I would like to generate a 5 col x 1 row data.table; the
> question is ?how??
>
> ?cl? represents the column names; ?rw? the row values.
>
> With anticipatory thanks ?
> John
> ______________________________________________
> 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.
>
	[[alternative HTML version deleted]]

Hi, thanks for the comprehensive reply; it is appreciated.
John Staples

Sent from my iPad
> On 6 Jun 2022, at 14:05, John RF Staples <john.staples at me.com>
wrote:
> 
> ?Hello everyone,
> 
> I have the following two structures:
> 
> # str(cl)
> # chr [1:5] "timestamp" "assess" "catheter"
"service" "ref"
> 
> # str(rw)
> # chr [1:5] "1654508112" "3" "gel"
"2785" ?16545081121a8d8f956cb871053a3f56b782b70a76"
> 
> From which I would like to generate a 5 col x 1 row data.table; the
question is ?how??
> 
> ?cl? represents the column names; ?rw? the row values.
> 
> With anticipatory thanks ?
> John