根据索引使用元素填充单元格数组 [英] Fill cell array with elements based on the indices MATLAB
问题描述
我有一个n * m个单元格Cell_In:
I have a n*m cell array Cell_In:
a b
* *
* *
c *
* d
* *
* f
*->表示空字符串('').这是我需要的:
* --> represents empty string (''). Here is what I need:
a b
a b
a b
c b
c d
c d
c f
对于特定的列,我需要用先前的非空单元格填充空单元格,直到找到另一个非空单元格为止.以下是我编写的代码.
For a particular column I need to fill the empty cell with the previous non-empty cell until another non-empty cell is found. Following is the code what I wrote.
b = ~cellfun(@isempty,a);
c = [find(b(:,1) == 1);size(a,1)+1]; e = diff(c);
d = [find(b(:,2) == 1);size(a,1)+1]; f = diff(d);
s1 = ''; s2 = '';
for i = 1:length(e)
s1 = [s1,repmat(a(c(i),1),1,e(i))];
end
for i = 1:length(f)
s2 = [s2,repmat(a(d(i),2),1,f(i))];
end
Cell_Out = [s1',s2'];
它工作正常,但我想知道最好的解决方案?
It's working fine but I want to know the best solution?
推荐答案
假定A
是输入单元格数组,这里可能有两种方法.
Assuming A
to be the input cell array, there could be two approaches here.
方法1
%// Initlialize output array
Aout = cell(size(A));
for k = 1:size(A,2)
%// Select one column
Ak = A(:,k);
%// Logical array with size of Ak and ones at places with non-empty strings
pos = cellfun(@(x) ~isempty(x), Ak);
%// Find unique strings and find indices for all places in that column
%// with respect to those unique strings
[unq_str,~,str_idx] = unique(Ak,'stable');
%// Perform cumsum on pos to get an array with a "stepped" array that
%// steps up at each non-empty string position.
%// Then replace each stepping number with the string IDs
idx = changem(cumsum(pos),str_idx(pos),1:sum(pos));
%// Index into each column with those replaced IDs for the final output
Aout(:,k) = unq_str(idx);
end
为了稍微更积极地测试解决方案代码,输入略有更改,我们在代码运行后就拥有了
With the input slightly changed for testing out the solution code a bit more aggressively, we had after code run -
A =
'a' 'b'
'' ''
'' 'a'
'c' ''
'' 'd'
'a' ''
'' 'f'
'c' 'a'
Aout =
'a' 'b'
'a' 'b'
'a' 'a'
'c' 'a'
'c' 'd'
'a' 'd'
'a' 'f'
'c' 'a'
方法2 [紧凑,效率更高]
您可以将输入单元格数组整形为单列单元格数组,因此,您无需遍历 单元阵列,这可能会导致更高效,更紧凑的代码-
You can reshape the input cell array into a single columned cell array and as such you won't need to loop through the columns of the cell array and this could lead to a more efficient and compact code -
%// Reshape all cells into a single columned cell array
A1 = A(:);
%// Rest of the code borrowed from previous approach with reshaping added
%// at the end to bring the output back to the size of input array
pos = ~cellfun('isempty', A1);
[unq_str,~,str_idx] = unique(A1,'stable');
Aout = reshape(unq_str(changem(cumsum(pos),str_idx(pos),1:sum(pos))),size(A));
奖金:changem
Bonus: Customized implementation of changem
之前列出的代码使用 changem
,需要 Mapping Toolbox
.因此,如果有的话,这是它的自定义版本,使用bsxfun
和max
实现,并且只是
The codes listed earlier uses changem
that needs Mapping Toolbox
. So, if you do have it, here's a customized version of it, implemented with bsxfun
and max
and is merely a polished version of an earlier solution code posted here. Here goes the custom function code -
%// CHANGEM_CUSTOM Home-cooked vesion of CHANGEM with MAX, BSXFUN
function A = changem_custom(A,newvals,oldvals)
[valid,id] = max(bsxfun(@eq,A(:),oldvals(:).'),[],2); %//'
A(valid) = newvals(id(valid));
return;
因此,要使用此自定义函数替换changem
,只需替换先前代码中的函数调用名称即可.
So, to use this custom function to replace changem
, just replace the function call name there in the earlier codes.
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