I am trying to randomize a marker color

I have a graph that randomizes a point on the graph. I am also trying to randomize the marker color and edge color but then never change. He is what i have but I dont know how to fix it.

[Amanda]

Im trying to have one marker change colors everytime the code is ran

[Star Strider]

I have no idea what that means.

[Amanda]

I have a graph and there is a point with a marker color I need the color of the marker to change everytime

Answer 1

[Maik]

I assume the randi in your program was the problem. Here below we use it to generate a single

value everytime and pass it to the markersize plot handle.

close all 
x = sin(0:2*pi/100:2*pi);

x = 1×101

0 0.0628 0.1253 0.1874 0.2487 0.3090 0.3681 0.4258 0.4818 0.5358 0.5878 0.6374 0.6845 0.7290 0.7705 0.8090 0.8443 0.8763 0.9048 0.9298 0.9511 0.9686 0.9823 0.9921 0.9980 1.0000 0.9980 0.9921 0.9823 0.9686

figure;
plot(x, '-b*');

markerSize = [1:10]; 
% randi syntax [1,10] range of numbers to choose the random value, 
% 1,1 - number of random values to generate 
rand_idx = randi([1,10],1,1);
randMarkerSize = markerSize(rand_idx); 
figure;
h = plot(x, '-b*') 

h = 
  Line with properties:

              Color: [0 0 1]
          LineStyle: '-'
          LineWidth: 0.5000
             Marker: '*'
         MarkerSize: 6
    MarkerFaceColor: 'none'
              XData: [1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 … ]
              YData: [0 0.0628 0.1253 0.1874 0.2487 0.3090 0.3681 0.4258 0.4818 0.5358 0.5878 0.6374 0.6845 0.7290 0.7705 0.8090 0.8443 0.8763 0.9048 0.9298 0.9511 0.9686 0.9823 0.9921 0.9980 1 0.9980 0.9921 0.9823 0.9686 0.9511 0.9298 0.9048 0.8763 … ]

  Show all properties

h.MarkerSize = randMarkerSize;

Answer 2

[Walter Roberson]

'b':'r':'g'

ans = 'b'

You have used the colon operator. 'b' <= 'g' so you get at least one value, but 'b' + 'r' > 'g' so you only get one value, the 'b'

You perhaps wanted ['b', 'r', 'g'] -- which is exactly the same as 'brg' in MATLAB.

You randi(5) but 5 has no relationship to the number of marker colors you have to select from. You should numel() the color vector to find the number of items to select from. Then once you have your random number, use it to index the color array.

disp random_markerSize

random_markerSize

Notice that displays the literal text random_markerSize . If you want to display the content of the variable random_markerSize then you need to use disp(random_markerSize)