R help - Apr 2009 - use the value of variable to quote certain elements in matrix

Hi, I want to use the value of variable to quote elements in matrix.
For example, I have a matrix like:
              y1   y2m1         1      2m2         3      4
where y1,y2,m1,m2 are column and row names.  I have two random character
variable, say x,  that could be either  y1 or y2  and  y that could be either m1
or m2.  So can I  do like   Matrix[y,x] to quote elements?  I've tried this
way but it simply use "x" and "y" itself  rather its value
as column or row names. I want to use the value of x and y as colunm or row
names.  So when x="y1" and y="m1" in cases,  I want to
matrix[x,y]=1. 
please help.



      
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Hi Weicheng,

Did you forget to add " " to index your elements? The following
example
works perfectly fine.

test.matrix = matrix(1:4,nrow=2) ;
rownames(test.matrix)=c("hi1","hi2") ;
colnames(test.matrix)=c("bye1","bye2") ;
test.matrix

    bye1 bye2
hi1    1    3
hi2    2    4

test.matrix["hi1","bye2"] ;

[1] 3

ran.row = sample(x=rownames(test.matrix),size=1) ;
ran.col = sample(x=colnames(test.matrix),size=1) ;
test.matrix[ran.row,ran.col] ;

Is this in a way what you were trying to get?

Best of luck,

Luc

weicheng wang wrote:
> Hi, I want to use the value of variable to quote elements in matrix.
> For example, I have a matrix like:
>               y1   y2m1         1      2m2         3      4
> where y1,y2,m1,m2 are column and row names.  I have two random character
variable, say x,  that could be either  y1 or y2  and  y that could be either m1
or m2.  So can I  do like   Matrix[y,x] to quote elements?  I've tried this
way but it simply use "x" and "y" itself  rather its value
as column or row names. I want to use the value of x and y as colunm or row
names.  So when x="y1" and y="m1" in cases,  I want to
matrix[x,y]=1.
> please help.
>
>
>
>       
> 	[[alternative HTML version deleted]]
>
>   
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