Opening mat files with uiopen and copying data to array

Question

banco freno 2019-4-17

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/456971-opening-mat-files-with-uiopen-and-copying-data-to-array

评论： Walter Roberson 2019-4-18

I have some mat files organized as cell arrays. All my mat files have the same structure and have progressive names, like MyFile_001, MyFile_002 and so on.

Copying data to arrays is an easy operation, such as

load('MyFile_001.mat')
Data1 = MyFile_001.Y(1).Data;
Data2 = MyFile_001.Y(2).Data;

but what if I want to choose which mat file to open instead of 'MyFile_001'?

The first row becomes

uiopen('load')

so I choose through GUI the file to be opened. How can I save data to arrays now?

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Stephen23 2019-4-17

It is not clear from your question: do the structures (very unfortunately) all have the same names as the file names (e.g. MyFile_001), or do they (sensibly) all have the same name (e.g. Y)?

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Stephen23 2019-4-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/456971-opening-mat-files-with-uiopen-and-copying-data-to-array#answer_371178

编辑：Stephen23 2019-4-18

在 MATLAB Online 中打开

It seems that whoever created those .mat files unfortunately named each structure with the same name as the filename, which just makes accessing the data more complex (it is much simpler to process a sequence of .mat files when their variable names are the same for each file).

Assuming that each .mat file contains exactly one variable (i.e. the structure), then you can work with these badly designed .mat files by ignoring the variable name entirely:

T = load(...);
T = struct2cell(T);
Data1 = T{1}.Y(1).Data;
Data2 = T{1}.Y(2).Data;

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

banco freno 2019-4-18

It works now, thanks!

请先登录，再进行评论。

Answer 2

Bob Thompson 2019-4-17

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/456971-opening-mat-files-with-uiopen-and-copying-data-to-array#answer_371080

It seems like your issue isn't so much opening specific files, but identifying new variables. With a bit of trickery you can identify what variables are new using who.

A = who;
uiopen;
Aprime = who;
new = cellfun(@(x) sum(ismember(A,x)),Aprime,'UniformOutput',0);
new = [Aprime([new{:}]~=1)];

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Stephen23 2019-4-17

Introspective programming (e.g. who) is slow and complex. See:

https://www.mathworks.com/help/matlab/matlab_prog/techniques-for-improving-performance.html

Simpler and more efficient to simply load into an output variable.

请先登录，再进行评论。

Answer 3

Walter Roberson 2019-4-17

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/456971-opening-mat-files-with-uiopen-and-copying-data-to-array#answer_371087

在 MATLAB Online 中打开

[filename, pathname] = uigetfile('*.mat');
if isnumeric(filename); error('cancel'); end
fullname = fullfile(pathname, filename);
datastruct = load(fullname, 'Y');
Data1 = datastruct.Y(1).Data;
Data2 = datastruct.Y(2).Data;

4 个评论
显示 2更早的评论隐藏 2更早的评论

Stephen23 2019-4-18

编辑：Stephen23 2019-4-18

"The mat files contain many fields and Y is one of them. Why do I get this message?"

Because this answer does not take into account the description of your .mat files, which apparently contain nested structures with the variable name the same as the filename (i.e. the files contain badly designed data).

Walter Roberson 2019-4-18

在 MATLAB Online 中打开

[filename, pathname] = uigetfile('*.mat');
if isnumeric(filename); error('cancel'); end
fullname = fullfile(pathname, filename);
datastruct = load(fullname);
fn = fieldnames(datastruct);    %data is stored in a struct named for the file
Data1 = datastruct.(fn{1}).Y(1).Data;
Data2 = datastruct.(fn{1}).Y(2).Data;