如何使用单元阵列重塑？

Question

不幸的是，我必须使用单元数组的数据集，它们甚至没有相同的输入.. 我的数据集（元胞数组的相关列）如下所示：

Data =
    1      'd2'      
    1      'd3'
    2      'u2'
    2      'd2'
    2      'u3'
    3      'e2'
    ...     ...

我想以某种方式重塑它们，即第一列中包含相同数字的所有行的第二列的所有输入都存储在新列中。因为第一列中每个数字的单行并不总是相同（但最高为 4），所以我编写了以下代码：

% creating 4 new cell arrays for the new columns
cells = cell(length(Data(:,1)),4);
Data = [Data,cells];

% reshaping Data
Data(:,3:6) = reshape(Data(Data(:,1) == 1,2),1,[]);
Data(:,3:6) = reshape(Data(Data(:,1) == 2,2),1,[]);

这可以完美地处理矩阵。但不幸的是，它不适用于单元阵列！ 请你帮我，我必须把大括号放在哪里，这样它会起作用吗？到目前为止我还没有得到它，也许我现在只是在监督它！ ;-)

非常感谢！

Answer 1

我个人认为在这种情况下循环是最简单灵活的解决方案：

mydata={1     'd2'      
    1      'd3'
    2      'u2'
    2      'd2'
    2      'u3'
    3      'e2'}

list = unique([mydata{:,1}])
result = {};

for t=1:numel(list)
    count=0;
    for u =1:size(mydata,1)
        if mydata{u,1}==list(1,t)
            count = count+1;
            result(t,count)=mydata(u,2)
        end
    end
end

请注意，矢量化方法可能会更有效，但除非您的数据很大，否则它应该无关紧要。

Answer 2

这可能是一种使用 bsxfun 的屏蔽功能的方法 -

%// Input
Data = {
    1      'd2'      
    1      'd3'
    2      'u2'
    2      'd2'
    2      'u3'
    3      'e2'}

%// Find the IDs and the unique IDs
ids = cell2mat(Data(:,1))
id_out = num2cell([1:max(ids)]') %//'# To be used as the first col of desired o/p

%// Find the extents of each group/ID members
grp_extents = sum(bsxfun(@eq,[1:max(ids)],ids),1)
%// Or use accumarray which could be faster -
%//        grp_extents = accumarray(ids,ones(1,numel(ids))).'

%// Get a cell array with the members (strings) from the second column of Data 
%// put into specific columns based on their IDs 
string_out = cell(max(grp_extents),numel(grp_extents))
string_out(bsxfun(@le,[1:max(grp_extents)]',grp_extents)) = Data(:,2) %//'# This is 
                           %// where the masking is being used for logical indexing

%// Transpose the string cell array and horizontally concatenate with 1D
%// cell array containing the IDs to form the desired output
Data_out = [id_out string_out']

输出 -

Data_out = 
    [1]    'd2'    'd3'      []
    [2]    'u2'    'd2'    'u3'
    [3]    'e2'      []      []