Seperating data into matrices based on names
显示 更早的评论
Hi,
I have a matrix of raw data stored in data.rawdata. Each row corresponds to a measurement which is labeled and the labels are stored at data.label. Labels could be repeated. So I want to seperate the data into different groups based on labels which I have been doing with the followid code:
data.labels=labels;
data.rawdata=rawdata;
groups=unique(data.labels);
for i=1:length(groups);
measurements{i,:}=data.rawdata((data.labels)==groups(i)),:);
end
I want to use the measurements that are seperated to save tt pp and pr results into seperate cells but brace indexing is not supported for this format inside the brackets...
for i=1:length(groups)
[tt{i,:},pp{i,:},pr{i,:}]=pca(measurements{i,:},10);
end
How can I do the pca calculations on different groups seperately? And how can I store the tt, pp, and pr seperately for different measurement groups?
I could do all this manually but the point is that I want to speed up the calculations by automizing
Another question which is of less importance:
is it possible to save the data in a cell array with different names with a code like: (I know this doesn'T work in the current format'
measurements.gourps(i)=data.rawdata((data.labels)==groups(i)),:);
I am looking forward to answers.
Thanks!
1 个评论
Ameer Hamza
2020-3-26
For the first part, you can directly use splitapply() instead of for loop to split your matrix; however, for this purpose, your code is also fine.
Now the error is actually caused by the left-hand side of
[tt{i,:},pp{i,:},pr{i,:}]=pca(measurements{i,:},10);
Can you make sure that the variables tt, pp, pr are not already defined with some other datatype.
采纳的回答
Peng Li
2020-3-26
I'm not sure what type do you use for data. Is that a table or a struct? I prefer using table. You can do findgroups first and a splitapply second on data, if it is a table.
[G, res] = findgroups(data(:, "labels"));
s = splitapply(@(x) {pca(x)}, data.rawdata, G);
the result s will be a cell array of length equaling to your number of unique labels.
If you data is a struct, you can use struct2table to convert it to table. prerequisite: data.labels is column vector with length equal to the row of data.rawdata.
8 个评论
Ameer Hamza
2020-3-26
The splitapply() will only capture the first output of pca(). The OP's code show that he want three outputs of the pca() function.
Peng Li
2020-3-26
s = splitapply(@(x){myPca(x)}, data.rawdata, G);
function y = myPca(x)
[a, b, c] = pca(x);
y{1} = a;
y{2} = b;
y{3} = c;
end
ardeshir moeinian
2020-3-26
编辑：ardeshir moeinian
2020-3-26
ardeshir moeinian
2020-3-26
Ameer Hamza
2020-3-26
ardeshir, You can use splitapply() without converting to table. Try
[G, ~] = findgroups(data.labels);
s = splitapply(@(x) {pca(x)}, data.rawdata, G);
function y = myPca(x)
[a, b, c] = pca(x);
y{1} = a;
y{2} = b;
y{3} = c;
end
Peng Li
2020-3-26
it doesn't matter if labels are integers or not. in above script, replace pca in splitapply with myPca in order for it to run.
Peng Li
2020-3-26
re your post on error regarding [G, res] = findgroups(data(:, "labels"));
after you convert from struct to table, what table variable names you have? Supposedly, labels should be a variable name. you can try [G, res] = findgroups(data.labels);
ardeshir moeinian
2020-4-30
更多回答（0 个）
类别
在 帮助中心 和 File Exchange 中查找有关 Logical 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
