Plotting struct with out first line

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dpreuben 2019-1-9

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/438917-plotting-struct-with-out-first-line

评论： dpreuben 2019-1-22

采纳的回答： Stephen23

Hi,

I have struct with 1801 X 921 elemants. I want to plot certain fields without the first row

so for example, if I use the following,

plot ([s.a(2,:)], [s.b(2,:)]);

it is giving error

can you please help me on this. Thanks.

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Stephen23 2019-1-10

编辑：Stephen23 2019-1-10

The structure has size 1801*1, and its first element's a and b fields contain arrays with sizes 1*1 and 1*4 respectively. This means that both a and b have exactly one row, so what you ask in your question does not make sense: "I want to plot certain fields without the first row". What data do you want to get from non-existent rows?

Possibly other elements of s have fields with more than one row, but you would still need to explain if single rows (like the ones you have shown) should be ignored, or throw an error, or whatever you need. Please upload the structure in a .mat file by clicking the paperclip button.

dpreuben 2019-1-22

编辑：dpreuben 2019-1-22

s.mat

Please find the matlfile attached. My aim is to plot s.a vs s.b

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采纳的回答

Stephen23 2019-1-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/438917-plotting-struct-with-out-first-line#answer_357462

s.mat

>> X = [s(2:end).a];
>> Y = [s(2:end).b];
>> plot(X,Y)
>> xlabel(s(1).a)
>> ylabel(s(1).b)

Read these to know more:

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists

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Stephen23 2019-1-22

编辑：Stephen23 2019-1-22

Whoever created that structure placed some character vectors (apparently the units of the numeric data) in the first element of s, i.e.:

s(1).a contains the char vector 's' (which has size 1x1).
s(1).b contains the char vector 'kg/h' (which has size 1x4).

All the rest of the data are numeric scalar. You could have easily found this out yourself, by looking at the data itself in the Variable Viewer. Or you could have looked at my answer, where I use those character vectors as the axes labels.

This is certainly an innovative way to store that data, but not a very efficient or clear (the numeric data would be efficiently stored in numeric arrays, and the units in their own fields).

Please remember to accept my answer!

dpreuben 2019-1-22

Thanks a lot Stephen.

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