apply text values to elements in a vector

I have a vector that is a sequence of number and NaN values. Is there a way for me to save values for these numbers and NaN values and then have the entire vector display with those text values inserted? For example:

If my vector is the column on the left below, and my variables are defined as

5 = turn left
4 = turn right
6 = go straight
NaN = not moving

can I get it to display as the column on the right after saving the variables?

5       turn left
5       turn left
5       turn left
4       turn right
4       turn right
4       turn right
6       go straight
6       go straight
6       go straight
NaN     not moving
5       turn left

Thanks in advance for the help!

Answer 1

[Cedric]

If you are allowed to remap "not moving" to e.g. code 1, you can proceed as follows:

 actions = [5,5,5,4,4,4,6,6,6,NaN,5] ;
 labels  = {'not moving', '', '', 'turn right', 'turn left', 'go straight'} ;

 % - NaN -> 1.
 actions(isnan(actions)) = 1 ;

 % - Display.
 for k = 1 : numel( actions )
    fprintf( '%d\t%s\n', actions(k), labels{actions(k)} ) ;
 end

With that, you get

 5  turn left
 5  turn left
 5  turn left
 4  turn right
 4  turn right
 4  turn right
 6  go straight
 6  go straight
 6  go straight
 1  not moving
 5  turn left

If you don't want that remap (NaN->1), it is easy to use an IF statement in a loop for managing NaN entries..

 actions = [5,5,5,4,4,4,6,6,6,NaN,5] ;
 labels  = {'turn right', 'turn left', 'go straight'} ;

 for k = 1 : numel( actions )
    if isnan( actions(k) )
        fprintf( 'NaN\tnot moving\n' ) ;
    else
        fprintf( '%d\t%s\n', actions(k), labels{actions(k)-3} ) ;
    end
 end

With that, you get

 5  turn left
 5  turn left
 5  turn left
 4  turn right
 4  turn right
 4  turn right
 6  go straight
 6  go straight
 6  go straight
 NaN  not moving
 5  turn left

[Muneer]

Thanks for the help, Cedric. If I had a 0 in my "actions" vector, when I assigned my labels in the "labels" vector, would the first label be for 0 or for 1?

[Cedric]

You're welcome. Indices in MATLAB start at 1, so you have to either add a condition in the FOR loop, e.g.

 for k = 1 : numel( actions )
    if isnan( actions(k) )
        fprintf( 'NaN\tnot moving\n' ) ;
    elseif actions(k) == 0
        fprintf( '0\tsome text\n' ) ;
    else
        fprintf( '%d\t%s\n', actions(k), labels{actions(k)-3} ) ;
    end
 end

Or you can just add 1 to actions and change NaN values into the first available integer > 1 which is not in regular actions.

[Muneer]

Thanks this seems to be working well. Can fprint be used to save the displayed column in its own vector? If not, I'm trying to define an output vector and have it write to the vector in the for loop. However, I'm confused about how to write string values within a vector.

[Cedric]

What would be the purpose? Any string is a vector of characters, or character array. If you wanted to save multiple strings (with various lengths), you could use a cell array. If the purpose is to create a log file, however, you can avoid saving these strings in variables but store them directly in the file.

[Muneer]

I wanted to be able to save the column of "text labels" so that I can display it again and verify accuracy in the next phase of the code that I'm working on. If I could type in the variable name, hit enter and have the entire column show up, it would make things a lot easier. Do you mean store them directly in the file created by fprintf? That may also be an acceptable option.

[Cedric]

You could generate a long string using SPRINTF ..

 actions = [5,5,5,4,4,4,6,6,6,NaN,5] ;
 labels  = {'not moving', '', '', 'turn right', 'turn left', 'go straight'} ;
 actions(isnan(actions)) = 1 ;
 temp   = [num2cell(actions); labels(actions)] ;
 report = sprintf( '%d\t%s\n', temp{:}) ;

With that, what was outputted to screen previously is now stored as a string in variable report, that you can display by typing its name in the command window.

A better option (up to me) would be to pack the code for printing the report in a function, and call the function when you want the report. This way you can easily get a dynamic report if actions evolve.

 function displayReport( actions )
    labels  = {'not moving', '', '', 'turn right', 'turn left', ...
               'go straight'} ;
    actions(isnan(actions)) = 1 ;
    for k = 1 : numel( actions )
       fprintf( '%d\t%s\n', actions(k), labels{actions(k)} ) ;
    end
 end

Saving this in file displayReport.m, you can then call it passing actions from the command window at any time (or from your script)..

 >> actions = [5,5,5,4] ;
 >> displayReport( actions ) ;
 5  turn left
 5  turn left
 5  turn left
 4  turn right

and a moment later, with more actions having stacked in your actions buffer ..

 >> actions = [5,5,5,4,4,4,6,6,6,NaN,5] ;
 >> displayReport( actions ) ;
 5  turn left
 5  turn left
 5  turn left
 4  turn right
 4  turn right
 4  turn right
 6  go straight
 6  go straight
 6  go straight
 1  not moving
 5  turn left