使用matlab进行文件夹内所有图片的顺序读取
文件夹：RBG25
在此，使用两种不同的方法来进行文件的读取，以及验证读取的顺序。（方法1符合大多数人的需求）
方法1：使用[路径，特定前缀，序号，后缀]
file_path = '.\RGB25\';% 图像文件夹路径 img_path_list = dir(strcat(file_path,'25_*.tif'));%dir 列出当前文件夹中的文件信息img_num = length(img_path_list)%获取图像总数量fprintf('正在读取的图像为：\n');if img_num > 0 %有满足条件的图像for j = 1:img_num %逐一读取图像img_name = [file_path,'25_',int2str(j),'.tif'];pitch=imread(img_name);%4色通道的fprintf('第%02d个：%s\n',j,img_name);endend
运行结果1为：
方法2：使用strcat和.name方法
file_path = '.\RGB25\';% 图像文件夹路径 img_path_list = dir(strcat(file_path,'25_*.tif'));%dir 列出当前文件夹中的文件信息img_num = length(img_path_list)%获取图像总数量fprintf('正在读取的图像为：\n');if img_num > 0 %有满足条件的图像for j = 1:img_num %逐一读取图像image_name = img_path_list(j).name;% 图像名image = imread(strcat(file_path,image_name));fprintf('第%d个：%s\n',j,strcat(file_path,image_name)); %显示正在处理的图像名endend
运行结果2为：
==========分界线哦~~=
问题：如果采用第二种方法（.name）来对图像进行自然排序读取可不可以呢？
答案是可以的。
先做个测试：试试.name的读序。
file_path = '.\RGB25\';img_path_list = dir(strcat(file_path,'*.tif'));img_num = length(img_path_list)img_path_list.name
结果如下所示：
也就是说：
采用img_path_list.name的读取方法，会先进行所有范围内最高位的最低数值读取；
什么意思呢？
1-29的所有图像，会先读取由1 开头的，故而顺序是：1-10-11-12-…-19-2-20-21…-29。
要怎么才能使得.name可以按人类思维一样，1-2-3-4…顺序读取呢？、
很简单，排序就好了。
通过编写一个排序函数sort_net.m，调用它来对文件夹内的图像进行排序。
img_name =sort_nat({img_path_list.name})
排序函数为：
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 % 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 < 2mode = '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_strnum_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, p = 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_descendindex = index(end:-1:1);endindex = reshape(index,size(c));cs = c(index);
这时候可以看看采用自然排序函数对文件名的读取：
file_path = '.\RGB25\';img_path_list = dir(strcat(file_path,'*.tif'));img_num = length(img_path_list);img_path_list.name;DirCell = struct2cell(img_path_list);Dir = sort_nat(DirCell(1,:))
显示结果如下，为cell数组型。
读取为cell数据：
Dir1 = Dir(1)
读取结果为：（cell）
读取为string数据：
Dir1 = Dir{1}
读取结果为：
将sort_net.m与string方式读取结合
最终代码为：
% 文件部分file_path = '.\RGB25\';img_path_list = dir(strcat(file_path,'*.tif'));img_num = length(img_path_list);% 文件名的数据类型处理DirCell = struct2cell(img_path_list);%把结构体数组转换成元胞数组Dir = sort_nat(DirCell(1,:)) %DirCell(1,:)表示第一1列（文件名）% 读取部分if img_num > 0 for j = 1:img_num Dir1 = Dir{j}image = imread(strcat(file_path,Dir1));fprintf('第%d个：%s\n',j,strcat(file_path,Dir1)); endend
最终效果为：
实现了对第2种读取方法的改写，使之能够按照自然排序方式读取。即1-2-3-4…
======END=
写在最后：*
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