CODEWITHSUNDEEP
rdata.table
sacvf
sacvf

Reputation: 2533

How to extract all columns when using data.table?

library(data.table)

I am trying to do this.

wd <- structure(list(Year = c(2006L, 2006L, 2006L), day = c(361L, 361L, 
360L), hour = c(14L, 8L, 8L), mint = c(30L, 0L, 30L), valu1 = c(0.5, 
0.3, 0.4), Date = structure(c(1167229800, 1167206400, 1167121800
), class = c("POSIXct", "POSIXt"), tzone = "UTC")), .Names = c("Year", 
"day", "hour", "mint", "valu1", "Date"), row.names = c(NA, -3L
), class = "data.frame")

wg <- c("2006/12/27 14:23:59", "2006/12/27 16:47:59", "2006/12/27 19:12:00")
w <- c("0.4", "0.2", "0.5")
wf=data.frame(wg,w)
wg <- as.POSIXct(wf$wg, format = "%Y/%m/%d %T", tz = "UTC") 
WG <- data.table(start = wg, end = wg)
setkey(WG)
## Do the same for `wd` adding +/- 30 minutes 
setDT(wd)[, `:=`(start = Date - 1800L, end = Date + 1800L)]
## Run foverlaps and extract the match `valu1` column
foverlaps(wd, WG, nomatch = 0L)[, .(wdDate = Date, valu1, WGDate = start)]
                    wdDate valu1              WGDate
   1: 2006-12-27 14:30:00   0.5 2006-12-27 14:23:59

As you can see in the final results only valu1 was extracted from wd but I would like also to extract the corresponding values from w in wf.

So I want something like this:

                     wdDate valu1              WGDate      w
    1: 2006-12-27 14:30:00   0.5 2006-12-27 14:23:59      0.4

Any idea is welcome.

Real data:

  head(wf)
       date1  date2        date3n               wg         w    whyt
1     <NA> 2003-01-01      <NA>                <NA>        NA   NA
2     <NA> 2003-01-02      <NA>                <NA>        NA   NA
3     <NA> 2003-01-03      <NA> 2003/01/03 10:30:00 0.2137352 0.34
4     <NA> 2003-01-04      <NA>                <NA>        NA   NA

Facing a problem here:

Upvotes: 2

Views: 88

Answers (1)

David Arenburg
David Arenburg

Reputation: 92300

In my previous answer I've created WG because you provided wg as a single vector. If you already have a data set called wf, this whole proccess is not needed. You just need to adjust wf correctly and then run foverlaps. In other words, forget about WG and do the following

setDT(wf)[, wg := as.POSIXct(wg, format = "%Y/%m/%d %T", tz = "UTC")]
wf[, `:=`(start = wg, end = wg)]
setkey(wf, start, end)
setDT(wd)[, `:=`(start = Date - 1800L, end = Date + 1800L)]

foverlaps(wd, wf, nomatch = 0L)[, .(wdDate = Date, valu1, WGDate = start, w)]
#                 wdDate valu1              WGDate   w
# 1: 2006-12-27 14:30:00   0.5 2006-12-27 14:23:59 0.4

Upvotes: 5

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