作者：tongqingliu

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# matlab对文件目录进行自然排序
[原博客阅读效果更佳。](http://www.cnblogs.com/liutongqing/p/7072878.html)
比如我新建一个tmp文件夹，在该文件夹下新建以下txt文件进行测试
```
a1.txt
a2.txt
a3.txt
a11.txt
a12.txt
b10.txt
```
返回到tmp的上一层文件夹，编写代码，查看该文件夹下的所有文件。
```matlab
clear;clc;close all
d = dir('tmp');
for i = 3:length(d)
disp(d(i).name)
end
```
MATLAB返回的结果是
```
a1.txt
a11.txt
a12.txt
a2.txt
a3.txt
b10.txt
```
WTF，什么鬼，有些时候我们不希望得到这样的结果，吓得我赶紧百度了一下
http://blog.csdn.net/g0m3e/article/details/52982737
看到这个人的博客，实现了我想要的结果，但是链接挂掉了。

换个地，找到了解决办法。

新建函数sort_nat.m

function [cs,index] = sort_nat(c,mode)

%sort_nat: Natural order sort of cell array of strings.

% usage:  [S,INDEX] = sort_nat(C)

%

% where,

%    C is a cell array (vector) of strings to be sorted.

%    S is C, sorted in natural order.

%    INDEX is the sort order such that S = C(INDEX);

%

% Natural order sorting sorts strings containing digits in a way such that

% the numerical value of the digits is taken into account.  It is

% especially useful for sorting file names containing index numbers with

% different numbers of digits.  Often, people will use leading zeros to get

% the right sort order, but with this function you don't have to do that.

% For example, if C = {'file1.txt','file2.txt','file10.txt'}, a normal sort

% will give you

%

%       {'file1.txt'  'file10.txt'  'file2.txt'}

%

% whereas, sort_nat will give you

%

%       {'file1.txt'  'file2.txt'  'file10.txt'}

%

% See also: sort

% Version: 1.4, 22 January 2011

% Author:  Douglas M. Schwarz

% Email:   dmschwarz=ieee*org, dmschwarz=urgrad*rochester*edu

% Real_email = regexprep(Email,{'=','*'},{'@','.'})

% Set default value for mode if necessary.

if nargin < 2

	mode = 'ascend';

end

% Make sure mode is either 'ascend' or 'descend'.

modes = strcmpi(mode,{'ascend','descend'});

is_descend = modes(2);

if ~any(modes)

	error('sort_nat:sortDirection',...

		'sorting direction must be ''ascend'' or ''descend''.')

end

% Replace runs of digits with '0'.

c2 = regexprep(c,'\d+','0');

% Compute char version of c2 and locations of zeros.

s1 = char(c2);

z = s1 == '0';

% Extract the runs of digits and their start and end indices.

[digruns,first,last] = regexp(c,'\d+','match','start','end');

% Create matrix of numerical values of runs of digits and a matrix of the

% number of digits in each run.

num_str = length(c);

max_len = size(s1,2);

num_val = NaN(num_str,max_len);

num_dig = NaN(num_str,max_len);

for i = 1:num_str

	num_val(i,z(i,:)) = sscanf(sprintf('%s ',digruns{i}{:}),'%f');

	num_dig(i,z(i,:)) = last{i} - first{i} + 1;

end

% Find columns that have at least one non-NaN.  Make sure activecols is a

% 1-by-n vector even if n = 0.

activecols = reshape(find(~all(isnan(num_val))),1,[]);

n = length(activecols);

% Compute which columns in the composite matrix get the numbers.

numcols = activecols + (1:2:2*n);

% Compute which columns in the composite matrix get the number of digits.

ndigcols = numcols + 1;

% Compute which columns in the composite matrix get chars.

charcols = true(1,max_len + 2*n);

charcols(numcols) = false;

charcols(ndigcols) = false;

% Create and fill composite matrix, comp.

comp = zeros(num_str,max_len + 2*n);

comp(:,charcols) = double(s1);

comp(:,numcols) = num_val(:,activecols);

comp(:,ndigcols) = num_dig(:,activecols);

% Sort rows of composite matrix and use index to sort c in ascending or

% descending order, depending on mode.

[unused,index] = sortrows(comp);

if is_descend

	index = index(end:-1:1);

end

index = reshape(index,size(c));

cs = c(index);

调用这个函数，在之前的代码中添加几行

clear;clc;close all

d = dir('tmp');

nameCell = cell(length(d)-2,1);

for i = 3:length(d)

    disp(d(i).name)

    nameCell{i-2} = d(i).name;

end

d2 = sort_nat(nameCell)

下面是见证奇迹的时刻

d2 =

    'a1.txt'

    'a2.txt'

    'a3.txt'

    'a11.txt'

    'a12.txt'

    'b10.txt'

这样就方便处理文件了。

参考：

http://cn.mathworks.com/matlabcentral/fileexchange/34464-customizable-natural-order-sort