R help - Jul 2009 - How to find the min and max of two variables in a data frame

I have two variables in a data frame, I want to generate two additional
variables. For every observations (i.e. every row), I want the first new
variable 'min' to carry the minimum of the two existing variables, and I
want the second new variable 'max' to carry the maximum of the two
existing
variables.  I then want to sort the data frame by min and max, and delete
duplicated rows if both rows has the same min and same max. 

I am new to R so not sure how to fix my code.  Here is my attempt and it is
not working.  Thanks!

edge_dir$min=edge_dir[if (edge_dir$cid_dir1 < edeg_dir$cid_dir2)
edge_dir$cid_dir1 else edge_dir$cid_dir2]
edge_dir$max=edge_dir[if (edge_dir$cid_dir1 > edeg_dir$cid_dir2)
edge_dir$cid_dir1 else edge_dir$cid_dir2]

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try this:

set.seed(123)
dat <- data.frame(x = round(rnorm(10)), y = round(rnorm(10)))

dat$Min <- pmin(dat$x, dat$y)
dat$Max <- pmax(dat$x, dat$y)
dat

ind <- dat$Min != dat$Max
dat[ind, ]


I hope it helps.

Best,
Dimitris


kxk wrote:
> I have two variables in a data frame, I want to generate two additional
> variables. For every observations (i.e. every row), I want the first new
> variable 'min' to carry the minimum of the two existing variables,
and I
> want the second new variable 'max' to carry the maximum of the two
existing
> variables.  I then want to sort the data frame by min and max, and delete
> duplicated rows if both rows has the same min and same max. 
> 
> I am new to R so not sure how to fix my code.  Here is my attempt and it is
> not working.  Thanks!
> 
> edge_dir$min=edge_dir[if (edge_dir$cid_dir1 < edeg_dir$cid_dir2)
> edge_dir$cid_dir1 else edge_dir$cid_dir2]
> edge_dir$max=edge_dir[if (edge_dir$cid_dir1 > edeg_dir$cid_dir2)
> edge_dir$cid_dir1 else edge_dir$cid_dir2]
> 
-- 
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014

edge_dir <- within(edge_dir, {
     vmin <- pmin(cid_dir1, cid_dir2)
     vmax <- pmax(cid_dir1, cid_dir2)
})


________________________________________
From: r-help-bounces at r-project.org [r-help-bounces at r-project.org] On
Behalf Of kxk [kkong at u.washington.edu]
Sent: 24 July 2009 15:31
To: r-help at r-project.org
Subject: [R]  How to find the min and max of two variables in a data frame

I have two variables in a data frame, I want to generate two additional
variables. For every observations (i.e. every row), I want the first new
variable 'min' to carry the minimum of the two existing variables, and I
want the second new variable 'max' to carry the maximum of the two
existing
variables.  I then want to sort the data frame by min and max, and delete
duplicated rows if both rows has the same min and same max.

I am new to R so not sure how to fix my code.  Here is my attempt and it is
not working.  Thanks!

edge_dir$min=edge_dir[if (edge_dir$cid_dir1 < edeg_dir$cid_dir2)
edge_dir$cid_dir1 else edge_dir$cid_dir2]
edge_dir$max=edge_dir[if (edge_dir$cid_dir1 > edeg_dir$cid_dir2)
edge_dir$cid_dir1 else edge_dir$cid_dir2]

--
View this message in context:
http://www.nabble.com/How-to-find-the-min-and-max-of-two-variables-in-a-data-frame-tp24638856p24638856.html
Sent from the R help mailing list archive at Nabble.com.

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