[R] Finding unique terms

[roslinazairimah zakaria]

Yes you are right, I want the sum. I wll change the formula accordingly.

On Fri, Oct 12, 2018 at 10:36 AM Jeff Newmiller <jdnewmil using dcn.davis.ca.us>
wrote:

> You said "add up"... so you did not mean to say that? Denes computed the
> mean...
>
> On October 11, 2018 3:56:23 PM PDT, roslinazairimah zakaria <
> roslinaump using gmail.com> wrote:
> >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.
> >> >
> >>
>
> --
> Sent from my phone. Please excuse my brevity.
>


-- 
*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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