Plotting array filtered by column?
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How would I go about graphing columns filtered by specific results in a third column?
The following table as an example, how would I plot only the second and third column entries that are 1.0000 in the first?
A =
1.0000 1.0000 5.5000
1.0000 2.0000 1.2000
0 3.0000 6.4000
1.0000 4.0000 3.7000
0 5.0000 3.6000
0 6.0000 9.6000
1 个评论
Dyuman Joshi
2023-7-19
编辑：Dyuman Joshi
2023-7-19
Try comparing with the first column values with 1.000, ideally with a tolerance, and use logical indexing to get the corresponding values in 2nd and 3rd column.
采纳的回答
% Define example points
A = [
1.0000 1.0000 5.5000
1.0000 2.0000 1.2000
0 3.0000 6.4000
1.0000 4.0000 3.7000
0 5.0000 3.6000
0 6.0000 9.6000];
% Define tolerance for finding rows to plot
tol = 1e-6;
% plot rows meeting critiera that element in first column is a 1
idl = ismembertol(A(:,1),1,tol); % or alternatively idl = abs(A(:,1)-1)<=tol
plot(A(idl,2),A(idl,3))
8 个评论
Jon
2023-7-21
Did this answer your question?
Brandon
2023-7-21
If you are filtering by a string then I assume the match would be exact, no tolerance involved. Also you couldn't store the numerical data and the strings in a double array, you would have to use some other structure, like a cell array. Here are some ways you could filter by a string:
% Define example points
A = {
'ABC' 1.0000 5.5000
'ABC' 2.0000 1.2000
'DEF' 3.0000 6.4000
'ABC' 4.0000 3.7000
'XYZ' 5.0000 3.6000
'PQT' 6.0000 9.6000};
% plot rows meeting critiera that element in first column is 'ABC'
idl = strcmp(A(:,1),'ABC');
figure
plot([A{idl,2}],[A{idl,3}]); % use [] to converts comma separated list to vector
% Or maybe a clearer way to do this, is to use a table
T = cell2table(A); % columns are named by default as A1,A2,A3
idl = strcmp(T.A1,'ABC');
figure
plot(T.A2(idl),T.A3(idl))
Brandon
2023-8-2
If you only want to plot rows where the element in the first column is either a 1 or a 2, then there are no tolerances involved. For this you can use basic logical indexing.
% Define example points
A = [
4 1.0000 5.5000
1 2.0000 1.2000
2 3.0000 6.4000
3 4.0000 3.7000
0 5.0000 3.6000
2 6.0000 9.6000];
% Plot rows meeting critiera that element in first column is a 1 or a 2
idl = A(:,1)==1 | A(:,1)==2
plot(A(idl,2),A(idl,3),'o-')
Brandon
2023-8-2
Dyuman Joshi
2023-8-2
Yes, that's cleaner and connects back to the beginning of the the thread where the match was approximate and we had to use ismembertol.
% Define example points
A = [
4 1.0000 5.5000
1 2.0000 1.2000
2 3.0000 6.4000
3 4.0000 3.7000
0 5.0000 3.6000
2 6.0000 9.6000];
% Plot rows meeting critiera that element in first column is a 1 or a 2
idl = ismember(A(:,1),[1,2])
plot(A(idl,2),A(idl,3),'o-')
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