[R] Dplyr question

[Rui Barradas]

Hello,

Right, intuitive is (very) relative. I was thinking of base function 
stats::reshape. Its main difficulty is, imho, to reshape to both wide 
and long formats. Compared to it, tidyr::pivot_* are (much?) easier to 
understand.

Here is a stats::reshape solution.


df_long <- reshape(
   data = df1,
   idvar = "Time_stamp",
   varying = list(2:3),
   v.names = "Measurement",
   direction = "long")

df_long$time <- sort(names(df1)[-1])[df_long$time]
names(df_long)[2] <- "Location"
df_long
#>                  Time_stamp Location Measurement
#> Jun-10 10:34.1 Jun-10 10:34 P190-90D   -0.000208
#> Jun-10 10:51.1 Jun-10 10:51 P190-90D   -0.000228
#> Jun-10 11:02.1 Jun-10 11:02 P190-90D   -0.000234
#> Jun-10 11:17.1 Jun-10 11:17 P190-90D   -0.000220
#> Jun-10 11:25.1 Jun-10 11:25 P190-90D   -0.000238
#> Jun-10 10:34.2 Jun-10 10:34  P1A0B0D   -0.000195
#> Jun-10 10:51.2 Jun-10 10:51  P1A0B0D   -0.000188
#> Jun-10 11:02.2 Jun-10 11:02  P1A0B0D   -0.000204
#> Jun-10 11:17.2 Jun-10 11:17  P1A0B0D   -0.000205
#> Jun-10 11:25.2 Jun-10 11:25  P1A0B0D   -0.000195


Hope this helps,

Rui Barradas

Às 19:25 de 21/06/2022, Bert Gunter escreveu:
> Heh heh. Well "intuitiveness" is in the mind of the intuiter. ;-)
> One might even say that Jeff's and John's solutions were the most 
> "intuitive" as they involved nothing more than the "straightforward" 
> application of standard base R functionality. (Do note the scare quotes 
> around 'straightforward'.) Of course, other factors may well be 
> decisive, such as efficiency, generalizability to the *real* problem and 
> data, and so forth.
> 
> Best to all,
> Bert
> 
> On Tue, Jun 21, 2022 at 10:50 AM Rui Barradas <ruipbarradas using sapo.pt 
> <mailto:ruipbarradas using sapo.pt>> wrote:
> 
>     Hello,
> 
>     pivot_longer is a package tidyr function, not dplyr. I find its syntax
>     very intuitive. Here is a solution.
> 
> 
> 
>     x <- "Time_stamp    P1A0B0D P190-90D
>     'Jun-10 10:34'  -0.000208   -0.000195
>     'Jun-10 10:51'  -0.000228   -0.000188
>     'Jun-10 11:02'  -0.000234   -0.000204
>     'Jun-10 11:17'  -0.00022    -0.000205
>     'Jun-10 11:25'  -0.000238   -0.000195"
>     df1 <- read.table(textConnection(x), header = TRUE, check.names = FALSE)
> 
>     suppressPackageStartupMessages({
>         library(dplyr)
>         library(tidyr)
>     })
> 
>     df1 %>%
>         pivot_longer(
>           cols = -Time_stamp,     # or starts_with("P1")
>           names_to = "Location",
>           values_to = "Measurement"
>         ) %>%
>         arrange(desc(Location), Time_stamp)
>     #> # A tibble: 10 × 3
>     #>    Time_stamp   Location Measurement
>     #>    <chr>        <chr>          <dbl>
>     #>  1 Jun-10 10:34 P1A0B0D    -0.000208
>     #>  2 Jun-10 10:51 P1A0B0D    -0.000228
>     #>  3 Jun-10 11:02 P1A0B0D    -0.000234
>     #>  4 Jun-10 11:17 P1A0B0D    -0.00022
>     #>  5 Jun-10 11:25 P1A0B0D    -0.000238
>     #>  6 Jun-10 10:34 P190-90D   -0.000195
>     #>  7 Jun-10 10:51 P190-90D   -0.000188
>     #>  8 Jun-10 11:02 P190-90D   -0.000204
>     #>  9 Jun-10 11:17 P190-90D   -0.000205
>     #> 10 Jun-10 11:25 P190-90D   -0.000195
> 
> 
> 
>     Hope this helps,
> 
>     Rui Barradas
> 
>     Às 17:22 de 21/06/2022, Thomas Subia escreveu:
>      > Colleagues:
>      >
>      > The header of my data set is:
>      > Time_stamp    P1A0B0D P190-90D
>      > Jun-10 10:34  -0.000208       -0.000195
>      > Jun-10 10:51  -0.000228       -0.000188
>      > Jun-10 11:02  -0.000234       -0.000204
>      > Jun-10 11:17  -0.00022        -0.000205
>      > Jun-10 11:25  -0.000238       -0.000195
>      >
>      > I want my data set to resemble:
>      >
>      > Time_stamp    Location        Measurement
>      > Jun-10 10:34  P1A0B0D -0.000208
>      > Jun-10 10:51  P1A0B0D -0.000228
>      > Jun-10 11:02  P1A0B0D -0.000234
>      > Jun-10 11:17  P1A0B0D -0.00022
>      > Jun-10 11:25  P1A0B0D -0.000238
>      > Jun-10 10:34  P190-90D        -0.000195
>      > Jun-10 10:51  P190-90D        -0.000188
>      > Jun-10 11:02  P190-90D        -0.000204
>      > Jun-10 11:17  P190-90D        -0.000205
>      > Jun-10 11:25  P190-90D        -0.000195
>      >
>      > I need some advice on how to do this using dplyr.
>      >
>      > V/R
>      > Thomas Subia
>      >
>      > FM Industries, Inc. - NGK Electronics, USA | www.fmindustries.com
>     <http://www.fmindustries.com>
>      > 221 Warren Ave, Fremont, CA 94539
>      >
>      > "En Dieu nous avons confiance, tous les autres doivent apporter
>     des donnees"
>      >
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