[R] Finding unique terms

[roslinazairimah zakaria]

Hi Denes,

It works perfectly as I want!

Thanks a lot.

On Fri, Oct 12, 2018 at 6:29 AM Dénes Tóth <toth.denes using kogentum.hu> wrote:

>
>
> On 10/12/2018 12:12 AM, roslinazairimah zakaria wrote:
> > Dear r-users,
> >
> > I have this data:
> >
> > structure(list(STUDENT_ID = structure(c(1L, 1L, 1L, 1L, 1L, 1L,
> > 2L, 2L, 2L, 2L, 2L), .Label = c("AA15285", "AA15286"), class = "factor"),
> >      COURSE_CODE = structure(c(1L, 2L, 5L, 6L, 7L, 8L, 2L, 3L,
> >      4L, 5L, 6L), .Label = c("BAA1113", "BAA1322", "BAA2113",
> >      "BAA2513", "BAA2713", "BAA2921", "BAA4273", "BAA4513"), class =
> > "factor"),
> >      PO1M = c(155.7, 48.9, 83.2, NA, NA, NA, 48.05, 68.4, 41.65,
> >      82.35, NA), PO1T = c(180, 70, 100, NA, NA, NA, 70, 100, 60,
> >      100, NA), PO2M = c(NA, NA, NA, 37, NA, NA, NA, NA, NA, NA,
> >      41), PO2T = c(NA, NA, NA, 50, NA, NA, NA, NA, NA, NA, 50),
> >      X = c(NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA), X.1 = c(NA,
> >      NA, NA, NA, NA, NA, NA, NA, NA, NA, NA)), .Names = c("STUDENT_ID",
> > "COURSE_CODE", "PO1M", "PO1T", "PO2M", "PO2T", "X", "X.1"), class =
> > "data.frame", row.names = c(NA,
> > -11L))
> >
> > I want to combine the same Student ID and add up all the values for PO1M,
> > PO1T,...,PO2T obtained by the same ID.
>
> dat <- structure(list(STUDENT_ID = structure(c(1L, 1L, 1L, 1L, 1L, 1L,
> 2L, 2L, 2L, 2L, 2L), .Label = c("AA15285", "AA15286"), class = "factor"),
>      COURSE_CODE = structure(c(1L, 2L, 5L, 6L, 7L, 8L, 2L, 3L,
>      4L, 5L, 6L), .Label = c("BAA1113", "BAA1322", "BAA2113",
>      "BAA2513", "BAA2713", "BAA2921", "BAA4273", "BAA4513"), class =
> "factor"),
>      PO1M = c(155.7, 48.9, 83.2, NA, NA, NA, 48.05, 68.4, 41.65,
>      82.35, NA), PO1T = c(180, 70, 100, NA, NA, NA, 70, 100, 60,
>      100, NA), PO2M = c(NA, NA, NA, 37, NA, NA, NA, NA, NA, NA,
>      41), PO2T = c(NA, NA, NA, 50, NA, NA, NA, NA, NA, NA, 50),
>      X = c(NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA), X.1 = c(NA,
>      NA, NA, NA, NA, NA, NA, NA, NA, NA, NA)), .Names = c("STUDENT_ID",
> "COURSE_CODE", "PO1M", "PO1T", "PO2M", "PO2T", "X", "X.1"), class =
> "data.frame", row.names = c(NA,
> -11L))
>
> # I assume you would like to add up the values with na.rm = TRUE
> meanFn <- function(x) mean(x, na.rm = TRUE)
>
> # see ?aggregate
> aggregate(dat[, c("PO1M", "PO1T", "PO2M")],
>            by = dat["STUDENT_ID"],
>            FUN = meanFn)
>
> # if you have largish or large data
> library(data.table)
> dat2 <- as.data.table(dat)
> dat2[, lapply(.SD, meanFn),
>       by = STUDENT_ID,
>       .SDcols = c("PO1M", "PO1T", "PO2M")]
>
>
> Regards,
> Denes
>
>
> >
> > How do I do that?
> > Thank you for any help given.
> >
>


-- 
*Roslinazairimah Zakaria*
*Tel: +609-5492370; Fax. No.+609-5492766*

*Email: roslinazairimah using ump.edu.my <roslinazairimah using ump.edu.my>;
roslinaump using gmail.com <roslinaump using gmail.com>*
Faculty of Industrial Sciences & Technology
University Malaysia Pahang
Lebuhraya Tun Razak, 26300 Gambang, Pahang, Malaysia

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