[R] how to find number of unique rows for combination of r columns

[Gerrit Eichner]

Hi, Ana,

doesn't

udt <- unique(dt[c("chr", "pos", "gene_id")])
nrow(udt)

get close to what you want?

  Hth  --  Gerrit

---------------------------------------------------------------------
Dr. Gerrit Eichner                   Mathematical Institute, Room 212
gerrit.eichner using math.uni-giessen.de   Justus-Liebig-University Giessen
Tel: +49-(0)641-99-32104          Arndtstr. 2, 35392 Giessen, Germany
http://www.uni-giessen.de/eichner
---------------------------------------------------------------------

Am 08.11.2019 um 15:38 schrieb Ana Marija:
> Hello,
> 
> I have a data frame like this:
> 
>> head(dt,20)
>       chr    pos         gene_id pval_nominal  pval_ret       wl      wr
>   1: chr1  54490 ENSG00000227232    0.6084950 0.7837780 31.62278 21.2838
>   2: chr1  58814 ENSG00000227232    0.2952110 0.8975820 31.62278 21.2838
>   3: chr1  60351 ENSG00000227232    0.4397880 0.8679590 31.62278 21.2838
>   4: chr1  61920 ENSG00000227232    0.3195280 0.6018090 31.62278 21.2838
>   5: chr1  63671 ENSG00000227232    0.2377390 0.9880390 31.62278 21.2838
>   6: chr1  64931 ENSG00000227232    0.2766790 0.9070370 31.62278 21.2838
>   7: chr1  81587 ENSG00000227232    0.6057930 0.6167630 31.62278 21.2838
>   8: chr1 115746 ENSG00000227232    0.4078770 0.7799110 31.62278 21.2838
>   9: chr1 135203 ENSG00000227232    0.4078770 0.9299130 31.62278 21.2838
> 10: chr1 138593 ENSG00000227232    0.8464560 0.5696060 31.62278 21.2838
> 
> it is very big,
>> dim(dt)
> [1] 73719122        8
> 
> To count number of unique rows for all 3 columns: chr, pos and gene_id
> I could just join those 3 columns and than count. But how would I find
> unique number of rows for these 4 columns without joining them?
> 
> Thanks
> Ana
> 
> ______________________________________________
> R-help using 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.
>