How can I plot only certain values from an array?

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Ahsan Khan
Ahsan Khan 2014-12-17
回答： Ankit Jain 2017-4-21
hi there, say I have an array [1,3,5,7,1,5,1,7,8,1]. I want to plot ONLY say value 1 from this array in accordance with the index in which the value resides in. so for the above array I want to plot for only value 1 occurrence: the value 1 shows up on index (0,4,6,and 9) so the plot will have an x-axis 1-10 and will only show a spike in the y direction when there is a value of 1 in the array. I have attached a an image as to what the result should look like. please help. thank you in advance. SN

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采纳的回答

Adam
Adam 2014-12-17
编辑：Adam 2014-12-17
a = [1,3,5,7,1,5,1,7,8,1];
idx = find( a == 1 );
figure; hAxes = gca;
stem( hAxes, idx, ones(numel(idx)) );
xlim( hAxes, [1 10] );
If you want to see the spikes more clearly you can also add e.g.
ylim( hAxes, [0 2] );
  1 个评论
Thorsten
Thorsten 2014-12-17
编辑：Thorsten 2014-12-17
Or as a one-liner :-)
stem(find(a==1), ones(numel(find(a==1))), 'k', 'Marker','None', 'LineWidth', 3), box off, axis([0 12 0 2])
and if you want just dots, use plot instead of stem:
plot(find(a==1), ones(numel(find(a==1))), 'ko', 'MarkerSize', 6, 'MarkerFaceColor', 'k')

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更多回答（2 个）

Sudharsana Iyengar
Sudharsana Iyengar 2014-12-17
just another method. This is round about way and will actually take more time to execute.
j=1;
for i=1:length(a)
if a(i)==1
b(j,1)=i;
b(j,2)=1;
j=j+1;
end
end
plot (b(:,1),b(;,2))
This will store the values of i for which the value is equal to 1. Which you can plot.
Ankit Jain
Ankit Jain 2017-4-21
Above all method are only applicable if the value to be plotted is same, what about if one wants varied values to be plotted?

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