Creating and filling Matrix, graphing results in STATA

[John Singer]

Hello all,
I'd like to fill a blank matrix in STATA with 2 columns and 5 rows I found this post from 2011 that suggested (for an 8 by 8 matrix).

 matrix mat1 = J(8,8,.)

so I tried

 matrix mat1 = J(5,2)

, which yielded an "invalid syntax error." Perhaps the command has changed and one should use MATA instead?

EDIT: I noticed I was missing the ,. so now I've managed to create the empty matrix and just have to do the rest.

After I have the matrix, I'd like the first column to be a value that I define. For example, in R the code would be:

mat[1, 1] <- log(10)
mat[2, 1] <- log(20)
mat[3, 1] <- log(30)
mat[4, 1] <- log(40)
mat[5, 1] <- log(50)

followed by filling the other columns for different observations (in this case, country years) and then plotting the results of the matrix. Again, the code in R is (where 1:50 refers to the number of observations and 1:5 is the matrix defined above).

for (j in 1:50) {
for (i in 1:5) {
  mat[i, 2] <- log(df[j, 1 + i])
}
mat <- as.data.frame(mat)
plot(mat$V2, mat$V1)
}

What is the best way to do this in STATA? Or do I necessarily have to use MATA instead? I'm not familiar with the latter. Basically, the end result should be 50 graphs, where the y-coordinate corresponds to column 1 in the matrix (and stays the same for each graph) and the x-coordinate corresponds to column 2. I just included the code in R in case it's helpful for explaining what I'm trying to do.

Let me know if this makes sense. Thank you in advance!

[Andrew Musau]

Assignment is straightforward in Stata

mat[1, 1] <- log(10)

mat mat1[1,1] = log(10)

See

help matrix

then plotting the results of the matrix.

In Stata, you normally don't create graphs using matrices. If you give a data example and explain what you want, suggestions may be forthcoming. Otherwise

help svmat

to convert the matrix to a dataset.

[Nick Cox]

I agree with Andrew Musau

 
 matrix mat1 = J(8,8,.)

in Stata creates a matrix with 8 rows and 8 columns and missing as every entry. In contrast

matrix mat1 = J(5,2)

offers two arguments to the function, but not three as are required. Hence it is illegal. It's certainly not a special case of the first command yielding a matrix with that size but no content, as you must have something in each matrix entry. . On the big picture I note that I wrote the post you cite from 2011 but I would have to do a lot of reading to re-discover the context. But it was true in 2011 and remains true that (with minor exceptions that don't undermine the major idea) that you need variables, not matrices, to draw a graph/

[Romildo Andrade]

hello nick
congrats on your posts!
By the way, I would like to ask if you are aware of how to "plot" in stata a graphic matrix like the one presented with the histograms on the diagonal and the correlation coefficients in the upper half and the scatter plots in the lower half?

[Nick Cox]

There is no quick way to do that in Stata that I know of.

[Romildo Andrade]

Do you think the support people could help or be interested in developing this type of output?
Any idea of someone who could 'develop' this command?