Non-uniform axis spacing in a plot

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Gianluca Ligresti
Gianluca Ligresti on 1 Feb 2019
Answered: Jianye Xu on 13 Aug 2022
Hi all,
I have two vectors: A = [0.5,0.65,0.7,0.66,0.81] and B = [5,10,20,100,1000]
I would like to plot A on the y-axis and B on the x-axis, so that the x-axis has a UNIFORM spacing of the 5 elements in B. Instead, if I simply use plot(B,A) I obtain the usual Matlab plot, in which the point 5,10,20,100 are very close one to the other on the x-axis, while 1000 is very distant.
How can I make this plot, having uniform spacing between the distante values in B?
Thanks
  2 Comments
madhan ravi
madhan ravi on 1 Feb 2019
xlim([0 1000])
xticks(linspace(min(B),max(B),numel(B)))
Gianluca Ligresti
Gianluca Ligresti on 1 Feb 2019
Sorry, probably I didn't explain well my problem.
On the x-axis I want to have ONLY the values 5, 10, 20, 100, 1000
Corresponding to 5 I want have 0.5 on the y-axis
Corresponding to 10 I want have 0.65 on the y-axis and so on
But I would like to have on the x-axis an equal distance between the value 5 and 10, between 10 and 20 I would have the same distance, between 20 and 100 I would have the same distance and so on

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Answers (4)

Steven Lord
Steven Lord on 1 Feb 2019
Edited: Steven Lord on 1 Feb 2019
About the only way you'll be able to get what you want is to lie a little bit.
A = [0.5,0.65,0.7,0.66,0.81];
B = [5,10,20,100,1000];
Plot the A data with X coordinates 1, 2, ... instead of the data in B. Don't worry, we'll use B soon.
plot(A);
Show only the ticks corresponding to those integer coordinates.
xticks(1:length(A));
Set the labels for those ticks to be the elements in B.
xticklabels(string(B))

Star Strider
Star Strider on 1 Feb 2019
Try this:
x = 10.^(rand( 1, 20)*3); % Create Data
y = rand(1, 20); % Create Data
A = [0.5,0.65,0.7,0.66,0.81];
B = [5,10,20,100,1000];
figure
plot(x, y, 'p')
set(gca, 'XScale','log', 'XTick',B, 'XTickLabel',B, 'YTick',sort(A))
The x-axis spacing is not absolutely uniform, however this is as likely as close as it is possible to get to what you want.

KSSV
KSSV on 1 Feb 2019
Edited: KSSV on 1 Feb 2019
Do interpolation....read about interp1
A = [0.5,0.65,0.7,0.66,0.81] ;
B = [5,10,20,100,1000] ;
plot(B,A,'*r')
hold on
Bi = linspace(min(B),max(B),100) ; % or you may use Bi = min(B):10:max(Bi)
Ai = interp1(B,A,Bi) ;
plot(Bi,Ai,'.-b')
  2 Comments
Gianluca Ligresti
Gianluca Ligresti on 1 Feb 2019
Sorry, probably I didn't explain well my problem.
On the x-axis I want to have ONLY the values 5, 10, 20, 100, 1000
Corresponding to 5 I want have 0.5 on the y-axis
Corresponding to 10 I want have 0.65 on the y-axis and so on
But I would like to have on the x-axis an equal distance between the value 5 and 10, between 10 and 20 I would have the same distance, between 20 and 100 I would have the same distance and so on
KSSV
KSSV on 1 Feb 2019
Edited: KSSV on 1 Feb 2019
That what the bove code does....or may be this fileexchange might be of your interest:

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Jianye Xu
Jianye Xu on 13 Aug 2022
Firstly, turn x-data to categorical data. Then, use plot():
A = [0.5,0.65,0.7,0.66,0.81];
B = [5,10,20,100,1000];
B_cat = categorical(B);
figure
plot(B_cat,A)
Hope that helps.

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