R help - Dec 2010 - from table to matrix

I have a table like this:

Date TIME  Q

A     a    1
A     b    2
A     c    3  
B     a    4
B     b    5
B     c    6
C     a    7
C     b    8
C     c    9

I want use R language to turn it to a matrix like :
    a  b  c 
A  1  2  3
B  4  5  6
C  7  8  9


I am new to R , anyone can help? Thanks in advance! have a table like this:

Date TIME  Q

A     a    1
A     b    2
A     c    3  
B     a    4
B     b    5
B     c    6


______________________________________
This email was sent by JESSICA (via Nabble)
Your replies will appear at
http://r.789695.n4.nabble.com/from-table-to-matrix-tp3087972p3087972.html
To receive all replies by email, subscribe to this discussion:
http://r.789695.n4.nabble.com/template/NamlServlet.jtp?macro=subscribe_by_code&node=3087972&code=ci1oZWxwQHItcHJvamVjdC5vcmd8MzA4Nzk3MnwtNzg0MjM1NTA4

	[[alternative HTML version deleted]]

Here's one way:
> df =
data.frame(Date=rep(LETTERS[1:3],each=3),TIME=rep(letters[1:3],3),Q=1:9)
> df
   Date TIME Q
1    A    a 1
2    A    b 2
3    A    c 3
4    B    a 4
5    B    b 5
6    B    c 6
7    C    a 7
8    C    b 8
9    C    c 9
> mat = matrix(0,3,3,dimnames=list(LETTERS[1:3],letters[1:3]))
> mat[as.matrix(df[,1:2])] = df[,3]
> mat
   a b c
A 1 2 3
B 4 5 6
C 7 8 9

 					- Phil Spector
 					 Statistical Computing Facility
 					 Department of Statistics
 					 UC Berkeley
 					 spector at stat.berkeley.edu

On Tue, 14 Dec 2010, JESSICA [via R] wrote:
>
> I have a table like this:
>
> Date TIME  Q
>
> A     a    1
> A     b    2
> A     c    3
> B     a    4
> B     b    5
> B     c    6
> C     a    7
> C     b    8
> C     c    9
>
> I want use R language to turn it to a matrix like :
>    a  b  c
> A  1  2  3
> B  4  5  6
> C  7  8  9
>
>
> I am new to R , anyone can help? Thanks in advance! have a table like this:
>
> Date TIME  Q
>
> A     a    1
> A     b    2
> A     c    3
> B     a    4
> B     b    5
> B     c    6
>
>
> ______________________________________
> This email was sent by JESSICA (via Nabble)
> Your replies will appear at
http://r.789695.n4.nabble.com/from-table-to-matrix-tp3087972p3087972.html
> To receive all replies by email, subscribe to this discussion:
http://r.789695.n4.nabble.com/template/NamlServlet.jtp?macro=subscribe_by_code&node=3087972&code=ci1oZWxwQHItcHJvamVjdC5vcmd8MzA4Nzk3MnwtNzg0MjM1NTA4
>
> 	[[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.
>

For contour plots,  some of the contour functions in graphics packages 
(lattice for one IIRC) are pretty good at understanding that columns in 
a matrix correspond to x,y, and z values already.





********

There are many ways to do this in R. For very simple problems, this one 
is convenient:

library(ecodist)
newdata <- crosstab(mydata$x, mydata$y, mydata$z)

For more complicated problems, reshape is very powerful.

Sarah

On Tue, Dec 14, 2010 at 5:13 PM, jonathan <jon_at_than.biz> wrote:
 >
 > That's so weird, I just signed up on here to ask exactly the same 
question!
 >
 > However, I think my issue is like Jessica's who says that her data is 
like
 > that, not actually that...
 >
 > So the issue is not in generating that data on-the-fly but in 
transforming
 > it from a data frame to a matrix.
 >
 > As a more concrete example, I have read the following data in from a file
 > (around 300,000 rows):
 >
 > x    y     z
 > 0    0    687
 > 0    1    64
 > 0    2    71
 > 0    3    55
 > 0    4    52
 > 0    5    51
 > 0    6    38
 > 0    7    38
 > 0    8    54
 > 0    9    49
 > .........
 > .........
 > .........
 > 304979    282977    1
 > 351377    1547980    1
 > 383835    1740541    1
 > 418133    6024710    1
 > 421549    1028572    1
 > 471314    1751836    1
 > 579602    1817393    1
 > 713515    5524385    1
 >
 >
 > So what I want to do is transform this into a matrix where at 
position (x,y)
 > in the matrix I have value z. I am doing this so that I can then do a
 > filled.contour plot on the data.
 >
 > I think this is the same as what Jessica is asking...
 >
 > Regards and many thanks,
 >
 > Jonathan
 > UCL Computer Science

______________________________________________
R-help@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.

	______________________________________
	View message @
http://r.789695.n4.nabble.com/from-table-to-matrix-tp3087972p3088156.html
	
	To unsubscribe from from table to matrix, visit
http://r.789695.n4.nabble.com/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=3087972&code=ci1oZWxwQHItcHJvamVjdC5vcmd8MzA4Nzk3MnwtNzg0MjM1NTA4
	[[alternative HTML version deleted]]

Thank you guys I learnt a lot .

But when I tried to run the library(ecodist) function,  R says there is no
package called "ecodist".
why? 
	______________________________________
	View message @
http://r.789695.n4.nabble.com/from-table-to-matrix-tp3087972p3088184.html
	
	To unsubscribe from from table to matrix, visit
http://r.789695.n4.nabble.com/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=3087972&code=ci1oZWxwQHItcHJvamVjdC5vcmd8MzA4Nzk3MnwtNzg0MjM1NTA4
	[[alternative HTML version deleted]]