Can't get data from input string

2021 6 22
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更新时间：2021 6 24
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Hi! I have gotten a data file which contains 57 different "keys" like 'XPOS' (x-position), YPOS (y-position), etc. Within these "keys" the data is stored in arrays. I want to ask the user "which dataset do you want to work with" and thus use this input in further calcualtions. I approached this in the same way I would in Python, but I have not gotten a usable result. My current code is attached.
For information, I would like the user to write "XPOS" as input.
The error I get is at the bottom of the code.
Thank you in advance!
data = load('x.mat');
name = input('Which dataset do you wanna work with? ','s');
if isempty(name)
reply = 'Y';
end
pos = data.name;
plot(data.Time,pos); %Just a simple plot of position against time
%%%%%% Mean, max, min calc %%%%%%
Mean = mean(pos);
Max = max(pos);
Min = min(pos);
Column = [['Max_ : ', num2str(Max)];['Min_ : ', num2str(Min)];['Mean : ', num2str(Mean)]];
disp(Column);
%%% MY ERROR %%%
Reference to non-existent field 'name'.
Error in plotter (line 20)
pos = data.name;

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Walter Roberson
Walter Roberson 2021-6-22

0 个投票

if ~isfield(data, 'name')
error('dataset "%s" is not loaded', name)
end
pos = data.(name);

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Vilde Solberg
Vilde Solberg 2021-6-22
Thank you for the respons.
When I try with you code, I get the error "dataset "%s" is not loaded". The problem is that it should be. When I manually use data.XPOS, everything runs smoothly, but when using pos = data.(name), it seems that it don't recognize XPOS.
For information, I have tried to calculate the mean (just for testing) as follows:
Mean = mean(pos);
Walter Roberson
Walter Roberson 2021-6-24
编辑：Walter Roberson 2021-6-24
if ~isfield(data, name)
error('dataset "%s" is not loaded', name)
end
pos = data.(name);
If data.XPOS works but name = 'XPOS'; data.(name) does not work, then please show
fn = fieldnames(data);
if ismember(name, fn)
fprintf('field "%s" IS found as a field name\n', name);
else
fprintf('field "%s" is NOT found as a field name\n\n', name);
for K = 1 : length(fn)
thisfield = fn{K};
fprintf('field #%d is %d characters long "%s". chars are: ', K, length(thisfield), thisfield);
fprintf('%s\n\n', mat2str(double(thisfield)));
end
end
This is intended as debugging code. It might, for example, help you through a situation where the stored field name turns out to be XP0S instead of XPOS

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