Unrecognized method, property, or field 'randi' for class 'rl.util.r​lFiniteSet​Spec'.

Hello,

I am trying to sample an action from the actionspace which is in the predefined MATLAB environment 'BasicGridWorld'.

env = rlPredefinedEnv('BasicGridWorld');
obsInfo = getObservationInfo(env);
actInfo = getActionInfo(env);
disp(obsInfo)
disp(actInfo)
a= actInfo.randi()

However the actInfo belongs to the class rl.util.rlFiniteSetSpec which does not support rand or randi method and is of type string.

I suppose I have to first convert it to type num and then randomly select 1 out of the 4 actions from that class?

Is this approach correct?

Answer 1

[Geoff Hayes]

@Ankita Tondwalkar - from here, actInfo is an array of rlNumericSpec objects | array of rlFiniteSetSpec objects. I think that you need to first determine the length of the array and then choose an integer between one and that length using randi.

[Ankita Tondwalkar]

@Geoff Hayes I did the following and this work.

A = ["N";"S";"E";"W"]

B= []

s = strrep(A,"N","1")

s1= strrep(s,"S","2")

s2= strrep(s1,"E","3")

s3 = strrep(s2,"W","4")

B = [s3]

Actions = cell2mat(arrayfun(@str2num,B,'uni',0))

randomIndex = randi(length(Actions), 1)

selected_A_value = Actions(randomIndex)