# How to make directories within directories within directories

34 views (last 30 days)

Show older comments

Hi,

The first loop 'for i=1..' creates 3 directories, '1,2,3'. The second loop, 'for n=1:..', then creates two directories inside each of them called 'a' and 'b'. The code is successful thus far. The final loop (list3) attempts to create two further directories 'q' and 'r' within 'a' and 'b'. This loop produces another a,b containing q,r, which is fine, but at the same level as 1,2,3 which is not. So I obtain mainfolder\(1&2&3)\(a&b) + mainfolder\(a&b)\(q+r), rather than the required mainfolder\(1&2&3)\(a&b)\(q+r). I was attempting to use mkdir as in the example: mkdir(Parentfolder, foldername) which creates the foldername within Parentfolder. Thanks in advance! Sorry for the long winded explanation and awkward notation

function testforum();

list1=["1","2","3"]

list2=["a","b"]

list3=["q","r"]

for i=1:length(list1)

x=list1(i)

mkdir(sprintf('%s',x))

for n=1:length(list2)

y=list2(n)

mkdir (sprintf('%s',x),sprintf('%s',y))

for p=1:length(list3)

z=list3(p)

mkdir (sprintf('%s',y),sprintf('%s',z))

end

end

end

end

### Accepted Answer

Jan
on 21 May 2018

Edited: Jan
on 21 May 2018

Use absolute paths for the folders. You cannot create a subfolder using the mkdir(parent, sub) notation, if parent is not found. Example:

base = 'D:\Temp'; % Assumed to be existing

cd(base);

mkdir('A'); % C:\Temp\A created

mkdir('A', 'B'); % C:\Temp\A\B created, because 'A' is found in current directory

mkdir('B', 'C'); % This creates C:\Temp\B\C, not C:\Temp\A\B\C

mkdir('A\B', 'C'); % This creates C:\Temp\A\B\C

Much easier:

mkdir(fullfile(base, 'A', 'B', 'C'))

Use full path names to avoid any troubles. The notation mkdir(parent, sub) was needed in Matlab R5.3, but after 20 years I suggest to use the modern power of mkdir to create a complete folder tree at once.

A fixed version of your code:

base = 'D:\Temp'; % Set as needed

list1 = {'1', '2', '3'}

list2 = {'a', 'b'}

list3 = {'q', 'r'}

for i = 1:length(list1)

x = list1{i}

for n = 1:length(list2)

y = list2{n}

for p=1:length(list3)

z = list3{p}

mkdir(fullfile(base, x, y, z));

end

end

end

##### 2 Comments

Guillaume
on 21 May 2018

### More Answers (1)

Guillaume
on 21 May 2018

Numbered variables are always an indication of a flawed design. Your algorithm is not easily extensible to adding more levels to your directory structure since it means adding another numbered variable and another for loop.

It would be much simpler to have a single variable and a recursion or a single loop. But since mkdir will create all the directories necessary, I would just build all the full paths and pass that in a loop:

lists ={["1","2","3"], ["a","b"], ["q","r"]};

%build the cartesian product of elements of lists:

cartprod = cell(size(lists));

[cartprod{:}] = ndgrid(lists{:});

%pass the cartesian product to fullfile to build the paths

allpaths = fullfile(cartprod{:});

%now iterate over all the paths

for pidx = 1:numel(allpaths)

mkdir(allpaths(pidx)); %will create all inexistant directories in the path

end

The above works with any number of levels, just add the extra level(s) to lists, up to the combinatorial limit of ndgrid.

### See Also

### Categories

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!