[R] DROP and KEEP statements in R

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My preferred solution would be to use the select option of the subset function.

> data ( iris )

> names ( iris )
[1] "Sepal.Length" "Sepal.Width"  "Petal.Length" "Petal.Width"  "Species"   

# KEEP-like way  
> iris_subset_by_keep <- subset ( iris, select = c( "Sepal.Length", "Species" ) )

# DROP-like way
> iris_subset_by_drop <- subset ( iris, select = c ( -Sepal.Width, -Petal.Length, -Petal.Width) )

> identical ( iris_subset_by_keep , iris_subset_by_drop )
[1] TRUE

> names ( iris_subset_by_keep )
[1] "Sepal.Length" "Species"     
>

p.s.
data NeweRa ( drop = SAS );
    set Much_Better;
    

eRic



----- Original message -----
From: "Wensui Liu" <liuwensui at gmail.com>
To: sarjinder at yahoo.com
Cc: r-help at r-project.org
Date: Sat, 19 Dec 2009 20:19:51 -0500
Subject: Re: [R] DROP and KEEP statements in R

drop example.
> data(iris)
> summary(iris)
  Sepal.Length    Sepal.Width     Petal.Length    Petal.Width
 Min.   :4.300   Min.   :2.000   Min.   :1.000   Min.   :0.100
 1st Qu.:5.100   1st Qu.:2.800   1st Qu.:1.600   1st Qu.:0.300
 Median :5.800   Median :3.000   Median :4.350   Median :1.300
 Mean   :5.843   Mean   :3.057   Mean   :3.758   Mean   :1.199
 3rd Qu.:6.400   3rd Qu.:3.300   3rd Qu.:5.100   3rd Qu.:1.800
 Max.   :7.900   Max.   :4.400   Max.   :6.900   Max.   :2.500
       Species
 setosa    :50
 versicolor:50
 virginica :50

> iris$Species <- NULL
> summary(iris)
  Sepal.Length    Sepal.Width     Petal.Length    Petal.Width
 Min.   :4.300   Min.   :2.000   Min.   :1.000   Min.   :0.100
 1st Qu.:5.100   1st Qu.:2.800   1st Qu.:1.600   1st Qu.:0.300
 Median :5.800   Median :3.000   Median :4.350   Median :1.300
 Mean   :5.843   Mean   :3.057   Mean   :3.758   Mean   :1.199
 3rd Qu.:6.400   3rd Qu.:3.300   3rd Qu.:5.100   3rd Qu.:1.800
 Max.   :7.900   Max.   :4.400   Max.   :6.900   Max.   :2.500

On Sat, Dec 19, 2009 at 3:21 PM, <sarjinder at yahoo.com> wrote:

> What is equivalent to DROP or KEEP statements of SAS in R?
>
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-- 
==============================
WenSui Liu
Blog   : statcompute.spaces.live.com
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