[R] efficiently replacing values in a matrix

[Nnamdi]

Still it is pretty slow when entering values into a large matrix. Case in
point:

> a <- matrix(nrow=10000,ncol=10000)
> system.time(a[1,1] <- 1903908.80385)
   user  system elapsed
 30.840   6.226  41.416
> is.matrix(a)
[1] TRUE

Is there a better way to enter values into large matrices? If I have to
spend 41 secs each time I enter into a cell and I have 10000x10000 cells to
enter that is impractical! 

--Nnamdi

Rolf Turner-3 wrote:
> 
> 
> On 17/04/2008, at 9:33 AM, Charles C. Berry wrote:
> 
> 	<snip>
> 
>> I'll lay odds that Matthew's 'matrix' is actually a data.frame, and  
>> I'll not be surprised if the columns are factors.
> 
> 	<snip>
> 
> I suspect that you're right.
> 
> ***Why*** can't people distinguish between data frames and matrices?
> If they were the same <expletive deleted> thing, there wouldn't be two
> different terms for them, would there?
> 
> 	cheers,
> 
> 		Rolf Turner
> 
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