bar plot with different color bars depending on height

Hello to all,

I have two matrices, lets say the below:

x = [1:10]
y= [13, 25, 34, 65, 78, 92, 54, 46, 39, 5]

I need a bar plot (x,y) where each bar has a different color depending on its height (y value). Colors should be from blue (low values) to red (high values). I also need to create the respective colorbar with an asceding step of 10

How can I create this bar plot?

Thanks in advance

Answer 1

[Mathieu NOE]

hello Giannis

see code below and ouput here :

clc
clearvars
x = [1:10];
y= [13, 25, 34, 65, 78, 92, 54, 46, 39, 5];


%% main code
map = colormap('jet');
[mmap,nmap] = size(map);
data_min = min(y);
data_max = max(y);

f= figure(1), hold on
for k = 1:length(y)
      h=bar(x(k),y(k));
    % now define col value based on data value (min data value maps to colormap map index 1
      % and max data value maps to colormap map last index);
      ind = fix(1+(mmap-1)*(y(k)-data_min)/(data_max-data_min));
      set(h, 'FaceColor', map(ind,:)) ;
    % Display the values as labels at the tips of the  bars. 
    xtips1 = h.XEndPoints;
    ytips1 = h.YEndPoints + 3;
    labels1 = string(h.YData);
    text(xtips1,ytips1,labels1,'HorizontalAlignment','center')
end

xlabel('X axis')
ylabel('Y axis')
hold off

CBAR_ticks = 10*(fix(min(y)/10):ceil(max(y)/10));
caxis([min(CBAR_ticks),max(CBAR_ticks)])

hcb=colorbar('Ticks',CBAR_ticks,'TickLabels',split(num2str(CBAR_ticks)));
hcb.Title.String = "Y range";
hcb.Title.FontSize = 13;

[Giannis Nikolopoulos]

Hello!! thank you for your answer. I wanted exactly that!! However when I run your code to my matlab (2019a) there is an error. It says:

"Unrecognized method, property, or field 'XEndPoints' for class 'matlab.graphics.chart.primitive.Bar'.

Error in test (line 18)

xtips1 = h.XEndPoints; "

There is something wrong with the XEndPoints... do you know what is going on?

Thank you

Giannis

[Giannis Nikolopoulos]

ok I commented these lines and now it runs ok!!

I didnt understand the formula of 'ind' !! where you based to use this function?is it a common methodology?

By thw way, I understand that you are trying to find the respective row of the color from the map matrix based on the y value...

[Mathieu NOE]

hello

I don't have the error (I run R2020b)

the ind formula is to actually set the color according to the colormap scale and the bar height.

[Giannis Nikolopoulos]

thank you very much!

[Vartika Agarwal]

I want to plot a 10 bars in bar graph with different colors

y=[20 10 5 3 12 18 25 20 30 40];

bar(y)

Can you help me for acheiving this