R help - Aug 2007 - rectify a program of seasonal dummies matrix

Hi friends, 
I would like to construct a matrix of seasonal dummies with number of rows
(observations)=100. such matrix is written as follows:[1 0 0 0;0 1 0 0;0 0 1 0;0
0 0 1;1 0 0 0;0 1 0 0;0 0 1 0;0 0 0 1;etc...] . I wrote the following program:
T=100
br=matrix(0,T,4)
{
for (i in 1:T)
for (j in 1:4)
if i==j
br[i,j]=1 
if else (abs(i-j)%%4==0
br[i,j]=1
else 
br[i,j]=0
}
z<-br
z 

but unfortunately I obtained from the console the following
message:
> {
+ for (i in 1:T)
+      for (j in 1:4)
+         (if i==j)
Erreur : syntax error, unexpected SYMBOL, expecting '(' dans :
"
"
>             br[i,j]=1
Erreur dans br[i, j] = 1 : objet "i" non
trouvé
> 
>         (if else (abs(i-j)%%4==0)
Erreur : syntax error, unexpected ELSE, expecting '(' dans "       
(if else"
>             br[i,j]=1
Erreur dans br[i, j] = 1 : objet "i" non
trouvé
>         else 
Erreur : syntax error, unexpected ELSE dans "       
else"
>             br[i,j]=0
Erreur dans br[i, j] = 0 : objet "i" non
trouvé
>               }
Erreur : syntax error, unexpected '}' dans "             
}"
>  
Can you please rectify my smal program, I tried to rectify it but I can't.
Many thanks in advance.
	[[alternative HTML version deleted]]

Your syntax is wrong; e.g.,
if i==j

should be

if (i == j)

same with your use of 'if else'.  You need to use the correct syntax.
Your example is hard to follow without the correct indentation since
you are using the incorrect syntax.

On 8/21/07, hassen62 at voila.fr <hassen62 at voila.fr>
wrote:
> Hi friends,
> I would like to construct a matrix of seasonal dummies with number of rows
(observations)=100. such matrix is written as follows:[1 0 0 0;0 1 0 0;0 0 1 0;0
0 0 1;1 0 0 0;0 1 0 0;0 0 1 0;0 0 0 1;etc...] . I wrote the following program:
> T=100
> br=matrix(0,T,4)
> {
> for (i in 1:T)
> for (j in 1:4)
> if i==j
> br[i,j]=1
> if else (abs(i-j)%%4==0
> br[i,j]=1
> else
> br[i,j]=0
> }
> z<-br
> z
>
> but unfortunately I obtained from the console the following message:
> > {
> + for (i in 1:T)
> +      for (j in 1:4)
> +         (if i==j)
> Erreur : syntax error, unexpected SYMBOL, expecting '(' dans :
> "
> "
> >             br[i,j]=1
> Erreur dans br[i, j] = 1 : objet "i" non trouv?
> >
> >         (if else (abs(i-j)%%4==0)
> Erreur : syntax error, unexpected ELSE, expecting '(' dans "  
(if else"
> >             br[i,j]=1
> Erreur dans br[i, j] = 1 : objet "i" non trouv?
> >         else
> Erreur : syntax error, unexpected ELSE dans "        else"
> >             br[i,j]=0
> Erreur dans br[i, j] = 0 : objet "i" non trouv?
> >               }
> Erreur : syntax error, unexpected '}' dans "             
}"
> >
> Can you please rectify my smal program, I tried to rectify it but I
can't. Many thanks in advance.
>        [[alternative HTML version deleted]]
>
>
> ______________________________________________
> R-help at stat.math.ethz.ch 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.
>
>

-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?

Hello, 
 
the main problem seems to be the "if else", should be "else
if".

Your code is hard to read, maybe you should consider using more () {}: 

T <- 100;
br <- matrix(0,T,4);

for (i in 1:T) {
   for (j in 1:4) {
      if (i==j) {
         br[i,j] <- 1;
       }
       else if ((abs(i-j)%%4)==0) {
          br[i,j] <- 1;
        }
        else {
          br[i,j] <- 0;
        }
    }
 }

A simpler approach is creating a diagonal matrix and multply it : 

# create small diagonal matrix
mat = diag(x=1, nrow=4, ncol=4);
mat
# multiply diagonal matrix and re-dimension it   to 4 cols
br <- rep(mat, 25);
dim(br) <- c(100, 4);
br;

Hope this helps, 
FS

-- 

Friedrich Schuster
mail at friedrich-schuster.de

Friedrich Schuster wrote:
> Hello, 
>  
> the main problem seems to be the "if else", should be "else
if".
> 
> Your code is hard to read, maybe you should consider using more () {}: 
> 
> T <- 100;
> br <- matrix(0,T,4);
Thanks for the contribution. Please note:
a) It is a bad idea to have a variable called T. Some people still use 
it as a logical value even if they should not.
b) R does not need any ";" at the end of a line.

Uwe Ligges

> for (i in 1:T) {
>    for (j in 1:4) {
>       if (i==j) {
>          br[i,j] <- 1;
>        }
>        else if ((abs(i-j)%%4)==0) {
>           br[i,j] <- 1;
>         }
>         else {
>           br[i,j] <- 0;
>         }
>     }
>  }
> 
> A simpler approach is creating a diagonal matrix and multply it : 
> 
> # create small diagonal matrix
> mat = diag(x=1, nrow=4, ncol=4);
> mat
> # multiply diagonal matrix and re-dimension it   to 4 cols
> br <- rep(mat, 25);
> dim(br) <- c(100, 4);
> br;
> 
> Hope this helps, 
> FS
>