matlab scatter with different colors by reading a file data

Hi. I am just a pure beginner of Matlab. I want to use Matlab scatter with different colors by reading a file data.

For example, consider that a.txt file has 6X6 data like following.

10, 20, 30 , 40, 50, 60

14 , 18, 17, 26, 39 ,11

red, blue, red, red, blue, green

10, 20, 30 , 40, 50, 60

19 , 88, 13, 7, 56 ,21

black, red , grey, black, black, red

First,second, the forth, the fifth lows are number. The third and the sixth lows are text.

Now I want to make at first 6 dots on 2-dimension screen with 3 differe colors. (red, blue, green) and (with pause) the next 6 dots on 2-dimension screen with 3 differe colors. (black, grey, red)

First and forth lows are the x value and second and fifth lows are the y value the dots of x-y plane.

How can I code matlab for this problem?

I tried make the code like this for the three lows.

fileID1 = fopen('a.txt','r');
formatSpec = '%f %f %s';
sizeA = [3 Inf];
A = fscanf(fileID1,formatSpec,sizeA)
x=A(1,:)
y=A(2,:)
z=A(3,:)
scatter(x,y,20,z,'filled')

But this failed because I don't know the exact usage of 'formatSpec'. Also I don't know how break the 6 lows with 3X6 matrix.

I hope your help.

Answer 1

[Walter Roberson]

Break it up into several pieces:

cnames = {'black', 'blue', 'green', 'grey', 'red'};
cmap = [
    0 0 0; %black
    0 0 1; %blue
    0 1 0; %green
    .5 .5 .5; %grey
    1 0 0;  %red
    ];

fileID1 = fopen('a.txt','r');

while true
   tx = fgetl(fileID1);
   ty = fgetl(fileID1);
   tc = fgetl(fileID1);
   if ~ischar(tx) || ~ischar(ty) || ~ischar(tc); break; end  %end of file
   x = sscanf(tx, '%f,', [1 inf]);
   y = sscanf(ty, '%f,', [1 inf]);
   innames = regexp(tc, '\s*,\s*', 'split');
   [found, idx] = ismember(innames, cnames);
   if ~all(found)
     error('color "%s" is unknown', innames{find(~found,1)});
   end
   c = cmap(idx,:);
   scatter(x, y, 200, c, 'filled');
end

[호철 신]

It works! great. Thank you!