how to create 3 scatter plots in same one figure in different color

I have three x,y data sets (TS01-TA01, TS10-TA10, TS20-TA20), and I want to read these data sets and create 3 scatter plots in same one figure in different color. but following my code does not overlap. please give me advice.

x1filename = ('TS20040101.txt');
y1filename = ('TA20040101.txt');
x1 = load(x1filename);
y1 = load(y1filename);
x2filename = ('TS20040110.txt');
y2filename = ('TA20040110.txt');
x2 = load(x1filename);
y2 = load(y1filename);
x3filename = ('TS20040120.txt');
y3filename = ('TA20040120.txt');
x3 = load(x1filename);
y3 = load(y1filename);
scatter(x1,y1);
hold on;
scatter(x2,y2,[],'r');
scatter(x3,y3,[],'c');
hold off;
xlabel('surface temperature');
ylabel('near-surface air temperature');

[mizuki]

This is double-posted also in Japanese (and already answered.) -

散布図の重ね合わせ

Answer 1

[Image Analyst]

When you load x2 and y2, you're passing in the x1 and y1 filenames, not the x2 and y2 filenames like you should. Same problem for #3 - you're passing in the x1 filenames instead of the x3 filenames. To fix:

x1filename = ('TS20040101.txt');
y1filename = ('TA20040101.txt');
x1 = load(x1filename);
y1 = load(y1filename);
x2filename = ('TS20040110.txt');
y2filename = ('TA20040110.txt');
x2 = load(x2filename);
y2 = load(y2filename);
x3filename = ('TS20040120.txt');
y3filename = ('TA20040120.txt');
x3 = load(x3filename);
y3 = load(y3filename);
scatter(x1,y1);
hold on;
scatter(x2,y2,[],'r');
scatter(x3,y3,[],'c');
hold off;
xlabel('surface temperature');
ylabel('near-surface air temperature');