Stair plot to vertical bar plot in Matlab - matlab

Question

I want to create a vertical bar plot. This is my code:
bar (x, sensiv);
title ('Promedio X')
xlabel('Nm')
ylabel('Refl.')
The problem is it looks like a stair plot. I've tried to add (x,sensiv, 'stacked') but it doesn't work. It looks grouped, as you can see in the next image:
graph http://imageshack.us/a/img689/9449/capturawv.jpg
I think it's because of x-axis but I couldn't change it. How can I do it? Does somebody knows how can I do it?
EDIT
Thanks Colin! I've tried to zoom and I understand what you mean and I've tried with different values, as slayton and you said.
I think that maybe it's the way I've code the plot, it is possible?
abc=0;
for p=(61:201)
abc(p)=out1_c;
end
for p=(151:301)
abc(p)=out2_c;
end
for p=(231:380)
abc(p)=out3_c;
end
for p=(381:596)
abc(p)=out4_c;
end
for p=(1152:1531)
abc(p)=out5_c;
end
for p=(1651:2051)
abc(p)=out7_c;
end
for p=(2052:2151)
abc(p)= 0;
end

Answer 1

The default value for the width of the bars in a bar plot is 0.8, so given that you're not currently specifying the width, you should have gaps in between each bar. This is going to sound really obvious, but have you tried zooming in on the bar plot that is created? For some datasets, the bar function will return a plot that looks like a stair plot, but in fact has gaps if you zoom in far enough. If this is the case, then you should be able to get the gaps you want by tinkering with the width parameter as suggested by slayton.
EDIT
Okay. First things first. If you want to post additional information, you should add it to your question, NOT post it as a new answer! You can do this by clicking the edit button just below where your question is on the page. To make things more readable, you might preface your edit with a capitalized bold-face heading "EDIT" as I have done here. If you are able, try now to move the additional information you've given back into your question, and then delete the answer.
Second, I have to be honest, the additional information you posted was somewhat confusing. However, I think I understand what you want now. You want 7 bars coming up to the heights out1_c, out2_c, ..., out7_c (variable names taken from your additional information) with a small gap between each bar, and the x-axis to reflect (approximately) the intervals 450-550, 550-650, etc.
Well, if you want 7 bars, then you want your input to only have seven elements. Set:
y = [out1_c; out2_c; out3_c; out4_c; out5_c; out6_c; out7_c];
y now gives you the heights your bars will come up to on the y-axis. To locate the bars on the x-axis, define a vector x that also has seven elements, where each element gives the midpoint of where you want the bar to be on the x-axis. For example:
x = [100; 200; 300; 400; 500; 600; 700];
Then just use bar(x, y). This should get you started.
A final point on the code you posted, you can actually completely avoid the loops: read up on vectorization. But if you are going to insist on loops, the first and most important rule is to preallocate your vectors/matrices. In your code abc starts out as a scalar (a 1 by 1 matrix), but then for every p, you are adding an element at index p. What is actually happening in the background is for every p, matlab is scrapping the current abc you have in memory, and building it again from scratch with the additional element. As you might expect, this will slow down your code by many orders of magnitude.

Answer 2

You can set the width of the individual bars by passing a value between 0 and 1 to bar. Passing 1 indicates that there should be no space between the bars
bar(x,y,1)
Passing anything less than 1 will reduce the bar sizes and introduce spacing between the individual bars
bar(x,y,.5)