# [R] How to get the rowindices without using which?

Dimitris Rizopoulos dimitris.rizopoulos at med.kuleuven.be
Mon Sep 26 10:51:41 CEST 2005

```try this:

dat <- iris[sample(1:nrow(iris), 10), ]
dat
match(rownames(dat), rownames(iris))

I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://www.med.kuleuven.be/biostat/
http://www.student.kuleuven.be/~m0390867/dimitris.htm

----- Original Message -----
From: "Martin Lam" <tmlammail at yahoo.com>
To: "R" <r-help at stat.math.ethz.ch>
Sent: Monday, September 26, 2005 10:37 AM
Subject: [R] How to get the rowindices without using which?

> Hi,
>
> I was wondering if it is possible to get the
> rowindices without using the function "which" because
> I don't have a restriction criteria. Here's an example
> of what I mean:
> # take 10 randomly selected instances
> iris[sample(1:nrow(iris), 10),]
>
> # output
>    Sepal.Length Sepal.Width Petal.Length Petal.Width
>  Species
> 76           6.6         3.0          4.4         1.4
> versicolor
> 105          6.5         3.0          5.8         2.2
> virginica
> 131          7.4         2.8          6.1         1.9
> virginica
> 79           6.0         2.9          4.5         1.5
> versicolor
> 69           6.2         2.2          4.5         1.5
> versicolor
> 42           4.5         2.3          1.3         0.3
>   setosa
> 25           4.8         3.4          1.9         0.2
>   setosa
> 129          6.4         2.8          5.6         2.1
> virginica
> 60           5.2         2.7          3.9         1.4
> versicolor
> 80           5.7         2.6          3.5         1.0
> versicolor
>
> What I want to get are their rownumbers: 76, 105, 131,
> 79, 69, 42, 25, 129, 60, 80.
>
> Thanks in advance,
>
> Martin
>
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