Re: [R] sort a data.frame

[David Winsemius]

But you should both be warned that would only be correct for a species  
where there were 24  chromosomes. This would work for humans and  
species with a higher number:

dd[ order(as.numeric(substring(dd$b, 4), substring(dd$b, 4))), ]
--
David Winsemius, MD
West Hartford, CT


On May 20, 2010, at 10:24 PM, Jorge Ivan Velez wrote:

Hi Yuan,

One way would be:

dd[order(factor(substring(dd$b, 4), levels = c(1:22,  
LETTERS[1:25]))),]

HTH,
Jorge


On Thu, May 20, 2010 at 10:18 PM, Yuan Jian <> wrote:

it's a excellent solution. I am sorry I missed something in my  
question.
the column b consists of not only number but also one letter after  
"chr",
for example chrX, chrY. I want to put them after number but in the  
order of
ASCII.
i.e. chr1<chr2<....<chr9<chr10<...<chr22<chrA<...chrX<chrY

if I have dataframe
dd <- data.frame(b = c("chr2", "chr1", "chrY", "chr13", "chrX"),
     x = c("A", "D", "A", "C", "C"), y = c(8, 3, 9, 9,7),
      z = c(1, 1, 1, 2, 8))

the expected result

      b x y z
1  chr1 D 3 1
2  chr2 A 8 1
3  chr13 C 9 2
4  chrX C 7 8
5  chrY A 9 1





--- On *Thu, 20/5/10, Jorge Ivan Velez <jorgeivanve...@gmail.com>*  
wrote:


From: Jorge Ivan Velez <jorgeivanve...@gmail.com>
Subject: Re: [R] sort a data.frame
To: "Yuan Jian" <jayuan2...@yahoo.com>
Cc: r-help@r-project.org
Received: Thursday, 20 May, 2010, 1:31 PM


Hi Yuan,

Try

dd[order(as.numeric(gsub("[^0-9]", "", dd$b))), ]

HTH,
Jorge

On Thu, May 20, 2010 at 8:28 AM, Yuan Jian <> wrote:

Hello,

I have a dataframe:
dd <- data.frame(b = c("chr2", "chr1", "chr15", "chr13"),
     x = c("A", "D", "A", "C"), y = c(8, 3, 9, 9),
      z = c(1, 1, 1, 2))

dd
     b x y z
1  chr2 A 8 1
2  chr1 D 3 1
3 chr15 A 9 1
4 chr13 C 9 2

Now I want to sort them according column "b", but only its number is
considered:
     b x y z
1  chr1 D 3 1
2 chr13 C 9 2
3 chr15 A 9 1
4  chr2 A 8 1

thanks
jian

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