How do you write a function that will sort a one-dimensional array using looping and conditionals without using the sort or sortrow commands?

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Jose Canseco
Jose Canseco 2012-10-8
In this problem, you are asked to write a function that will sort a one-dimensional array using looping and conditionals without using the sort or sortrow commands. Create a function called MySort.m, which takes as an input a 1-dimensional vector and sorts the values in a specifed order (ascending or descending). If no order is specifed, the default should be to sort in ascending order.
Function Header: function output = MySort(input, method)
The second input to the MySort, method, should be a string 'ascending' or 'descending'. If the function is called with only one argument, i.e. output = MySort(input), then the data in input should be sorted in ascending order. Hint: Use the variable nargin inside MySort and consider making use of the min and max functions and for or while when sorting.
% Test Cases
>> x = [1 5 3 5 2 10];
>> y1 = MySort(x,'ascending')
y1 =
1 2 3 5 5 10
>> y11 = MySort(x)
y11 =
1 2 3 5 5 10
>> y2 = MySort(x, 'descending')
y2 =
10 5 5 3 2 1

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采纳的回答

Sean de Wolski
Sean de Wolski 2012-10-8
编辑：Sean de Wolski 2012-10-8
This oughtta do it. (And steal the win from Greg :) )
function v2 = MySort(v,direction)
[~,~,idx] = unique(v(:));
v2 = cell2mat(accumarray(idx,v(:),[],@(x){x}));
if nargin==2&&strcmp(direction,'descending')
v2 = flipud(v2);
end
for ii = 1
v2 = reshape(v2,size(v));
end

更多回答（3 个）

Greg Heath
Greg Heath 2012-10-8
编辑：Greg Heath 2012-10-8
Find minx = min(x) at index indmin
x(indmax) = [];
y1 = [ y1 minx ];
Hope this helps enough so that you will formally accept my answer.
Greg
  1 个评论
John D'Errico
John D'Errico 2012-10-8
While this offers a poor scheme that can work when coupled with the proper logic, it must be made to work when the array has duplicates, which will take some careful logic. It is poor because it is terribly inefficient, doing far more tests than one should do in a sort. Note also that that this scheme has arrays that are constantly changing in size, so it will be an allocation nightmare.

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Jose Canseco
Jose Canseco 2012-10-8
编辑：Jose Canseco 2012-10-8
function output = MySort(input,method)
for x = 1:length(input)
if(length(input) <= 1)
output=input;
elseif(length(input)>1)
while (length(input)> 1)
if(method(x)==str('ascending'))
output=(min(input):max(input));
elseif(method(x)==str('descending'))
output=(max(input):min(input));
elseif(method(x)==str(''))
output=(min(input):max(input));
end
end
end
end
end
I can't seem to find what the problem is.
Matt J
Matt J 2012-10-8

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