Bar graph doesn't show bars

Question

Batuhan Arik 2021-10-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1468766-bar-graph-doesn-t-show-bars

评论： Batuhan Arik 2021-10-9

Hello everyone, I am trying to plot a bar graph with duplicate x values. I want to sum the y values of the duplicate x values. I found some help on the internet which seems to be working. However, when I try to run the code, axes appear bur bars don't appear.

here is my code;

clc
close all
x=X(:,1);
y=X(:,2);
[xnew,~,idx] = unique(x,'rows');
ynew = accumarray(idx(:),y(:));
hold on
bar(xnew,ynew);
hold on
title('X-Ray');
xlabel('E (kEV)');
ylabel('Yıllık Kullanım Yüzde Miktarı (mCi)');
grid minor

and here how it looks when I run it

I couldn't figure out the reason. Any help is appreciated. Thanks in advance.

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Walter Roberson 2021-10-7

在 MATLAB Online 中打开

As outside observers, we do not know that any of the ynew values are non-zero and not nan.

min(x), max(x)
min(y), max(y)
min(ynew), max(ynew)

Batuhan Arik 2021-10-7

oh sorry, I forgot to mention it. I checked the data, y_new, x_new, x, y are all as they are supposed to be.

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Answer 1

Prateek Rai 2021-10-9

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1468766-bar-graph-doesn-t-show-bars#answer_804976

在 MATLAB Online 中打开

Figure 1.png

To my understanding, you are trying to plot a bar graph with duplicate x values bur bars don't appear.

I think the problem is that the y values for duplicate x values are summing up to zero which is why you are not able to see the bars.

I will illustrate this with your example but with some arbitrary values.

x=[7,1,2,3,1,4,5,1,2,3,7,7,]';
y=[1,1,2,3,4,5,6,7,8,9,0,-1]';

I am using arbitrary x and y values here such that:

We have duplicate x values
We have duplicate x = 7 such that corresponding y value sums to 0 ( x = 7 y =1 , x = 7 y =0, x = 7 y = -1 ==> x = 7 y = 0)

Now, I will use a code similar to the code provided, and let's look at the possible bar graph.

clc

close all

x=[7,1,2,3,1,4,5,1,2,3,7,7,]';

y=[1,1,2,3,4,5,6,7,8,9,0,-1]';

[xnew,~,idx] = unique(x,'rows');

ynew = accumarray(idx(:),y(:));

hold on

bar(xnew,ynew);

hold on

title('X-Ray');

xlabel('E (kEV)');

ylabel('Yıllık Kullanım Yüzde Miktarı (mCi)');

grid minor

You can see the resultant plot in the attachment.

It is clear from the plot that we cannot see a bar for the case when x=7 because at that time the corresponding y sums to 0.

You can also refer to bar MathWorks documentation page to learn more on bar graph.

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Batuhan Arik 2021-10-9

Thanks for your effort. I have solved the problem. Actually, there was not even an actual problem. My array included too many elements. Thus, the bars were so tiny that they were invisible. Only thing I had to do was to increase bar width to 700000. It wass all my carelessness. Sorry for wasting your time.

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