How to get rid of certain xticklabels?

I have a plot that use log2 for x-axis. Now I want to get rid of xticklabels such as 1.41421, 2.82843, etc., and add 28 to the xticklabels. Namely, I would like to have xticklabels as [1, 2, 4, 8, 16, 28, 32]. Note that the constraint is to use log2 instead of original datapoints for x-axis because I want to somehow show linear speedup. How to do that?

compTime_1by1 = [1088.43, 603.71, 354.15, 236.48, 180.46, 159.06];
compTime_2by1 = [2196.49, 1179.91, 648.38, 413.79, 299.63, 268.45];
compTime_3by1 = [3238.68, 1729.27, 930.70, 590.57, 419.56, 337.15];

speedup_1by1 = compTime_1by1(1) ./ compTime_1by1;
speedup_2by1 = compTime_2by1(1) ./ compTime_2by1; 
speedup_3by1 = compTime_3by1(1) ./ compTime_3by1; 

numberOfCPUCores = [1, 2, 4, 8, 16, 28];

h1 = plot(log2(numberOfCPUCores), speedup_1by1, '-ob');
set(h1, 'MarkerFaceColor', get(h1,'Color'));

hold on;
h2 = plot(log2(numberOfCPUCores), speedup_2by1, '-or');
set(h2, 'MarkerFaceColor', get(h2,'Color'));

hold on;
h3 = plot(log2(numberOfCPUCores), speedup_3by1, '-ok');
set(h3, 'MarkerFaceColor', get(h3,'Color'));

xt = get(gca, 'XTick');
set(gca, 'XTickLabel', 2.^xt);

set(gca, 'FontSize', 14);
title('Parallel Scalability Test');
legend('Aspect ratio = 1 : 1', 'Aspect ratio = 2 : 1', 'Aspect ratio = 3 : 1', 'Location', 'best');
xlabel('Number of CPU cores');
ylabel('Speed-up');

grid on; grid minor;

Answer 1

[Star Strider]

‘Namely, I would like to have xticklabels as [1, 2, 4, 8, 16, 28, 32].’

It does exactly that when I plot it using the online Run feature here —

compTime_1by1 = [1088.43, 603.71, 354.15, 236.48, 180.46, 159.06];
compTime_2by1 = [2196.49, 1179.91, 648.38, 413.79, 299.63, 268.45];
compTime_3by1 = [3238.68, 1729.27, 930.70, 590.57, 419.56, 337.15];

speedup_1by1 = compTime_1by1(1) ./ compTime_1by1;
speedup_2by1 = compTime_2by1(1) ./ compTime_2by1; 
speedup_3by1 = compTime_3by1(1) ./ compTime_3by1; 

numberOfCPUCores = [1, 2, 4, 8, 16, 28];

h1 = plot(log2(numberOfCPUCores), speedup_1by1, '-ob');
set(h1, 'MarkerFaceColor', get(h1,'Color'));

hold on;
h2 = plot(log2(numberOfCPUCores), speedup_2by1, '-or');
set(h2, 'MarkerFaceColor', get(h2,'Color'));

hold on;
h3 = plot(log2(numberOfCPUCores), speedup_3by1, '-ok');
set(h3, 'MarkerFaceColor', get(h3,'Color'));

xt = get(gca, 'XTick');
set(gca, 'XTickLabel', 2.^xt);

set(gca, 'FontSize', 14);
title('Parallel Scalability Test');
legend('Aspect ratio = 1 : 1', 'Aspect ratio = 2 : 1', 'Aspect ratio = 3 : 1', 'Location', 'best');
xlabel('Number of CPU cores');
ylabel('Speed-up');

grid on; grid minor;

Since it is apparenlty not doing that for you, perhaps defining —

set(gca, 'XTick',(1:5), 'XTickLabel',2.^(1:5))

will provide the desired result.

.

Answer 2

[Matt J]

    h1 = plot(log2(numberOfCPUCores), speedup_1by1, '-ob');
    set(h1, 'MarkerFaceColor', get(h1,'Color'));

hold on;

    h2 = plot(log2(numberOfCPUCores), speedup_2by1, '-or');
    set(h2, 'MarkerFaceColor', get(h2,'Color'));
    
    h3 = plot(log2(numberOfCPUCores), speedup_3by1, '-ok');
    set(h3, 'MarkerFaceColor', get(h3,'Color'));
    
hold off
   
xticks(log2(numberOfCPUCores));
xticklabels(numberOfCPUCores);


set(gca, 'FontSize', 14);
title('Parallel Scalability Test');
legend('Aspect ratio = 1 : 1', 'Aspect ratio = 2 : 1', 'Aspect ratio = 3 : 1', 'Location', 'best');
xlabel('Number of CPU cores');
ylabel('Speed-up');
grid on; grid minor;