Bar diagram as subplot in a for loop from a cell

So i have a for loop which calculates some data and after i plot everything i want a subplot as a bar diagramm. I fit a linear curve to my data and want the gradient of the linear regression as the bar value. for each dataset is should take out the first value. If i try it with a simple example as at the end with a and b(i) it works fine but my bar diagramm only shows the value of p{1,1}(1) with the color of c{2} ? I am so confused and thankful for evey help.

number = numel(data)
for i = 1:number 
    p{i} = polyfit(x_relevant{i}, y_relevant{i},1)
    subplot(4,1,4)
    b(i) = bar(p{1,i}(1),'FaceColor',c{i})         % each data set, take out first value
    hold on 
    a = {[1 2], [3 4]}
    b(i) = a{1,i}(1)
end

Answer 1

[Adam Danz]

The goal is unclear but I think this is what your looking for,

number = numel(data);
for i = 1:number 
    p{i} = polyfit(x_relevant{i}, y_relevant{i},1);
end
coefs = cell2mat(p(:));
subplot(4,1,4)
b = bar(coefs(:,1));
bh.FaceColor = 'flat'; 
bh.CData = c;  % where c is something like c=jet(numel(b.XData));

If not, please provide more details.

[Patrick Petre]

Yes thats exactly what i was looking for. Could you explain why my approach was wrong or didnt work?

[Adam Danz]

I'd be happy to.

The main idea is to use the loop to gather the data and then organize the data into a matrix rather that using the loop to do the plotting. If you want a single bar plot with n-bars, you need a vector of n-values. Instead, your vector only contained 1 value on each iteration and you were merely adding another bar on top of the existing bars at x=1.

number = numel(data);  % <--- minor, but add semicolon suppression 
for i = 1:number 
    p{i} = polyfit(x_relevant{i}, y_relevant{i},1)
    subplot(4,1,4)  % <--- not necessary to call within the loop
    b(i) = bar(p{1,i}(1),'FaceColor',c{i}) % <--- **All bars will be at x=1, on top of each other
    hold on  % <--- not necessary at all
    a = {[1 2], [3 4]} % <--- ??? this is a mystery to me
    b(i) = a{1,i}(1) % <--- ??? this is a mystery to me
end

[Patrick Petre]

The last 2 rows was to test the syntax and the b(i) actually contained the values 1 and 3 after running the for loop. Thats why i was confused why my bar plot only contains one value.

On the other hand.. while running the for loop each loop contains one color stored in c which gives all the plots from one set of data the same color.