按升序排序,但最后保持零

时间:2013-06-02 11:03:39

标签: matlab sorting

假设我有一个矩阵A,在下面的表格中。

A =
    35     1     6
     3    32     0
     0     9     0
     0     0     0

我想按升序排序,但最后保留零。

我知道我可以使用inf替换所有零,对其进行排序,并再次将inf替换为零,如this question中所提议的那样。

我认为有一种更简单的方法。至少因为我的零已经在底行。我可以一行完成吗?

我想要的是什么:

A =
     3     1     6
     35    9     0
     0     32    0
     0     0     0

谢谢!

更新

关于Eitan答案的开销存在疑问。以下是结果(平均值和热身后):

B =  kron(A,ceil(rand(2000)*1000));  % 8000x6000 matrix
C = B;

%% Eitan's solution:
t1 = tic; B(B ~= 0) = nonzeros(sort(B)); toc(t1)
Elapsed time is  1.768782 seconds.

%% From question text:
B = C;
t1 = tic; B(B==0)=Inf; B = sort(B); B(B==Inf)=0; toc(t1) 
Elapsed time is 1.938374 seconds.

%% evading's solution (in the comments):
B = C;
t1 = tic; for i = 1:size(B,2)  index = B(:,i) ~= 0; B(index, i) = sort(B(index, i)); end
toc(t1)
Elapsed time is 1.954454 seconds.

%% Shai's solution (in the comments):
B = C;
t1 = tic; sel = B==0; B(sel)=inf;B=sort(B);B(sel)=0; toc(t1)
Elapsed time is 1.880054 seconds.

1 个答案:

答案 0 :(得分:8)

如果您可以保证零只位于每列的底部,则可以执行以下操作:

A(A ~= 0) = nonzeros(sort(A));