Choose Language Hide Translation Bar  pmroz
Super User

## Simple Matrix Creation Question

I have some code where I need to pass a matrix with one value to highlight one row in a table box:

``````nw = new window("test",
tb = table box(
string col box("Col1", {"aa", "bb", "cc"}),
number col box("Col2", [1, 2, 3])
)
);
rm = ;
tb << set selected rows(rm);
``````

The row number to be highlighted is a variable.  I would like to use the simplest syntax to create the row number matrix using this variable.  These methods don't work:

``````a = 2;		// Need a matrix holding this variable value
b = [a];	// Doesn't work
c = [expr(a)];	// No
d = [eval(a)];	// No
e = [eval(expr(a))];	// No``````

These are the methods I came up with that do work:

``````// Works but so complicated...
f = eval(parse(evalinsert("[^a^]")));	// Yes

// Works too
g = ;
g = a;	// Yes``````

Is there a simpler one-liner that I'm missing?  I just want to create a matrix like  dynamically.

2 ACCEPTED SOLUTIONS

Accepted Solutions  Jeff_Perkinson Community Manager

## Re: Simple Matrix Creation Question

I think the Matrix() function will do what you're looking for:

``````//:*/
a=2;
b=matrix(a);
/*:

``````

``````a = 2;
nw = New Window( "test",
tb = Table Box(
String Col Box( "Col1", {"aa", "bb", "cc"} ),
Number Col Box( "Col2", [1, 2, 3] )
)
);
rm = Matrix( a );
tb << set selected rows( rm );``````
-Jeff

## Re: Simple Matrix Creation Question

The original process was to make a matrix from a scalar, so I guess you are asking how to return a scalar from a matrix. Use subscript to access any element in the matrix.

``````// make 1x1 matrix (one element)
a = ;

// obtain element with a script using row-wise index or [row,col] coordinate
b = a;
b = a[1,1];``````
Learn it once, use it forever!
5 REPLIES 5  Jeff_Perkinson Community Manager

## Re: Simple Matrix Creation Question

I think the Matrix() function will do what you're looking for:

``````//:*/
a=2;
b=matrix(a);
/*:

``````

``````a = 2;
nw = New Window( "test",
tb = Table Box(
String Col Box( "Col1", {"aa", "bb", "cc"} ),
Number Col Box( "Col2", [1, 2, 3] )
)
);
rm = Matrix( a );
tb << set selected rows( rm );``````
-Jeff  pmroz
Super User

## Re: Simple Matrix Creation Question

Ha - perfect!  Thanks Jeff.

## Re: Simple Matrix Creation Question

Hi,

How do I perform this concept in reverse?

a=

b=2

?

## Re: Simple Matrix Creation Question

The original process was to make a matrix from a scalar, so I guess you are asking how to return a scalar from a matrix. Use subscript to access any element in the matrix.

``````// make 1x1 matrix (one element)
a = ;

// obtain element with a script using row-wise index or [row,col] coordinate
b = a;
b = a[1,1];``````
Learn it once, use it forever!

## Re: Simple Matrix Creation Question

This works too:

``````a = 2;
// Concat scalar with empty matrix
b = a || [];
// Same, but in place
a ||= [];

Show(a, b);
/*:

a = ;
b = ;``````