big edge list to adjacency matrix

An embedded and charset-unspecified text was scrubbed...
Name: not available
URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20130312/3fae0624/attachment.pl>
Hello,

The following is a bit convoluted but will do it.

dat <- read.table(text = "
a1 b1 1
a2 b2 2
a3 b3 3
a1 b1 4
a3 b1 5
")

xtabs(V3 ~ V1 + V2, data = aggregate(V3 ~ V1 + V2, data = dat, FUN = max))

Hope this helps,

Rui Barradas

Em 12-03-2013 21:45, avinash sahu escreveu:
I have huge list of edges with weights.
a1 b1 w1
a2 b2 w2
a3 b3 w3
a1 b1 w4
a3 b1 w5
I have to convert it into 2 dim matrix
      b1                b2          b3
a1  max(w1,w4)   0           0
a2            0        w2         0
a3        w5          0           w3

if edges repeated take the maximum weights. How do this efficiently without
using for loop? Any idea.

thanks
Avi

	[[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Hi,

You could also do:
library(reshape2)
?dcast(dat,V1~V2,value.var="V3",max,fill=0)
#? V1 b1 b2 b3
#1 a1? 4? 0? 0
#2 a2? 0? 2? 0
#3 a3? 5? 0? 3

A.K.

----- Original Message -----
From: Rui Barradas <ruipbarradas at sapo.pt>
To: avinash sahu <avinash.sahu at gmail.com>
Cc: r-help at r-project.org
Sent: Tuesday, March 12, 2013 7:10 PM
Subject: Re: [R] big edge list to adjacency matrix

Hello,

The following is a bit convoluted but will do it.

dat <- read.table(text = "
a1 b1 1
a2 b2 2
a3 b3 3
a1 b1 4
a3 b1 5
")

xtabs(V3 ~ V1 + V2, data = aggregate(V3 ~ V1 + V2, data = dat, FUN = max))

Hope this helps,

Rui Barradas

Em 12-03-2013 21:45, avinash sahu escreveu:
I have huge list of edges with weights.
a1 b1 w1
a2 b2 w2
a3 b3 w3
a1 b1 w4
a3 b1 w5
I have to convert it into 2 dim matrix
? ? ?  b1? ? ? ? ? ? ? ? b2? ? ? ? ? b3
a1? max(w1,w4)?  0? ? ? ? ?  0
a2? ? ? ? ? ? 0? ? ? ? w2? ? ? ?  0
a3? ? ? ? w5? ? ? ? ? 0? ? ? ? ?  w3

if edges repeated take the maximum weights. How do this efficiently without
using for loop? Any idea.

thanks
Avi

??? [[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.