Re: [R] Finding unique terms

Tóth Dénes Fri, 12 Oct 2018 00:09:02 -0700



On 10/12/2018 08:58 AM, Dénes Tóth wrote:

On 10/12/2018 04:36 AM, Jeff Newmiller wrote:
You said "add up"... so you did not mean to say that? Denes computedthe mean...
Nice catch, Jeff. Of course I wanted to use 'sum' instead of 'mean'.

Oh, and one more note: If you have NAs in your columns, 'sum' is rarelythe aggregate statistic that you are after. Probably this is why mysubconscious statistician suggested 'mean'.

On October 11, 2018 3:56:23 PM PDT, roslinazairimah zakaria<roslina...@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.de...@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.


--
Dr. Tóth Dénes ügyvezető
Kogentum Kft.
Tel.: 06-30-2583723
Web: www.kogentum.hu

______________________________________________
R-help@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.

Re: [R] Finding unique terms

Reply via email to