[R] Selecting rows and columns of a data frame using relational operators

[Ulrik Stervbo]

Hi Tunga,

The function subset() is probably what you are looking for. You might also
want to look at a tutorial to understand the R syntax.

In addition, calling your data data is not a good idea because of the name
clash with the function data().

Hope this helps,
Ulrik

On Mon, 27 Feb 2017 at 13:10 Tunga Kantarcı <tungakantarci at gmail.com> wrote:

> Consider a data frame named data. data contains 4 columns and 1000
> rows. Say the aim is to bring together columns 1, 2, and 4, if the
> values in column 4 is equal to 1. We could use the syntax
>
> data(data[,4] == 1, c(1 2 4))
>
> for this purpose. Suppose now that the aim is to bring together
> columns 1, 2, and 4, if the values in column 4 is equal to 1, for the
> first 20 rows of column 4. We could use the syntax
>
> data(data[1:20,4] == 1, c(1 2 4))
>
> for this purpose. However, this does not produce the desired result.
> This is surprising at least for someone coming from MATLAB because
> MATLAB produces what is desired.
>
> Question 1: The code makes sense but why does it not produce what we
> expect it to produce?
>
> Question 2: What code is instead suitable?
>
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