Plot range of values as bars

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Thomas Burbey
Thomas Burbey on 22 Aug 2018
Commented: Star Strider on 16 Oct 2020
I'm trying to figure out how to plot a range of y values as bars. For example if my x-axis is days of the month, my bars would represent the range between the max and min temperatures for that day. The bar would be the shaded portion between the min and max values for each day. Kind of like a boxplot without all the statistical information included. Can't figure out how to do this. Any suggestions?

Accepted Answer

Star Strider
Star Strider on 22 Aug 2018
One approach:
Tmax = randi([25 30], 1, 10); % Create Data
Tmin = randi([15 20], 1, 10); % Create Data
days = 1:10; % Create Data
figure
plot([days; days], [Tmin; Tmax], 'LineWidth',5)
xlabel('Day')
ylabel('Temperature Range (°C)')
ylim([10 40])
xlim([0 11])
grid
Experiment to get the result you want.
  10 Comments
Brendan Görres
Brendan Görres on 16 Oct 2020
What if i want the days to be a string? So for exaple instead of 1 it would give out 'Jan 1st'
Star Strider
Star Strider on 16 Oct 2020
Brendan Görres — With this code, it would be necessary to plot against datenum numbers, then use datetick. (Note that I have not done that experiment.)
I am not certain how (or if) this code would work with datetime vectors, and I have not used it with them. See the documentation section on Plot Dates and Durations for details on plotting with them. If you want to do that, post it as a new Question.

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More Answers (4)

dpb
dpb on 22 Aug 2018
Edited: dpb on 22 Aug 2018
OK, the bar option works pretty easily, actually, with some handle-diving for how things are organized.
% first make up some data...
x=1:30; % 30 days hath...
y=[randi(90,size(x)); % max, min temp distributions
randi(70,size(x))];
ix=diff(y)<0; % fixup to make sure all
y(:,ix)=flipud(y(:,ix)); % max are > min
To use bar to get scaled as between min/max for the second bar, the bar definitions are intervals [0 L] and [L H-L] so the sum or max of second bar in the stacked plot is L+(H-L) = H instead of H+L if plot L,H as normal.
hB=bar([y(1,:); diff(y)].', ...
'stacked','FaceColor','flat','EdgeColor','w');
hB(1).CData=ones(length(x),3); % set the color of bottom to background (white)
ends up with
In the end, this doesn't seem much more effort to fix up actual temperature min/max data by the difference than would be to compute the error values for the errorbar solution. It's a little more abstract in needing to set the color for the one bar so with Steven's observation of the new property for the error bar ends lengths being able to be set, that's probably the better solution.
BTW, the idea of simply
delete(hB(1))
to clear the first bar instead of rewriting the 'CData' doesn't work-- bar then turns the plot into a standard bar plot with zero baseline; doesn't keep the 'stacked' property any longer.
  4 Comments
dpb
dpb on 22 Aug 2018
Edited: dpb on 22 Aug 2018
[Thomas Answer moved to comment...dpb]
I still get an error with the line: hB(1).CData =ones(length(x),3) as it doesn't know what CData is. I'm assuming this is trying to access the first column in the hB bar workspace. Is this a version issue? I'm running R2016b? Otherwise I get what you're doing. It seems to me that the bar function is simply too limited. I'd think this would be a fairly common practice to want to do what I'm asking here.
dpb
dpb on 22 Aug 2018
Edited: dpb on 22 Aug 2018
As noted before, hB(1) is the bottom bar; hB(2) is the top; the bar objects aren't by column but by level for 'stacked'
On 'CData', indeed the bar object was redefined sometime after R2016b; I am on R2017b here. For R2016b, modify the above to
hB=bar([y(1,:); diff(y)].','stacked','EdgeColor','w');
hB(1).FaceColor='w'; % set the color of bottom to background (white)
But, it seems to me that while interesting to show what can manage to be done with enough creativity, that Star's simple plot solution is the best way to go, isn't it?
And, yes, I fully agree that bar is terribly limited in both what it can do "out of the box" easily and in subsequently trying to mung on it to do obviously needed/wanted things. I've complained for 20+ years there should be something like 'baseline' on a column basis.

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Yuvaraj Venkataswamy
Yuvaraj Venkataswamy on 22 Aug 2018
  1 Comment
Thomas Burbey
Thomas Burbey on 22 Aug 2018
All the regular bar graphs start at the axis, there's no way to enforce a range where the bar doesn't extend to the axis, but rather the minimum value specified.

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Yuvaraj Venkataswamy
Yuvaraj Venkataswamy on 22 Aug 2018
For example,
if true
x = 1:1:12;
y = [34 23 47 28 41 35 21 18 38 20 30 32];
bar(x,y)
end
  2 Comments
Thomas Burbey
Thomas Burbey on 22 Aug 2018
This isn't what I'm after. I want the lower value of the bar to be a minimum value I specify. This simply has the lower extent of the bar at the axis y=0.
Yuvaraj Venkataswamy
Yuvaraj Venkataswamy on 22 Aug 2018
Edited: Yuvaraj Venkataswamy on 22 Aug 2018
You mean,
if true
ylim([min_value max_value])
end
For example, ylim([0 40]);

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Steven Lord
Steven Lord on 22 Aug 2018
It sounds like you want the errorbar function.
  3 Comments
Steven Lord
Steven Lord on 22 Aug 2018
For at least the first part of your comment, if you're using release R2016b or later you can use the CapSize property introduced in that release. I just checked in release R2018a and setting CapSize to 0 is allowed.
dpb
dpb on 22 Aug 2018
Ah, in that case, probably simpler than the bar...wasn't aware of that modification/new property.

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