In MATLAB I can define multiple functions in one file, with only the first defined function being visible external to that file. Alternatively, I can put each function in its own file and make them all globally visible through the path. I'm writing a menu driven application, where each menu item runs a different function. Currently, these are all in one big file, which is getting increasingly difficult to navigate. What I'd like to do is put groups of related functions into separate files.
I think I can do something like this by putting all the child functions into a separate directory and then adding the directory to the path in my parent function, but this feels a bit messy and inelegant.
Can anyone make a better suggestion?
Note: I'm most familiar with MATLAB 2006, but I'm in the process of upgrading to MATLAB 2009.
One suggestion, which would avoid having to modify the MATLAB path, is to use a private function directory. For example:
Let's say you have a function called test.m in the directory \MATLAB\temp\ (which is already on the MATLAB path). If there are local functions in test.m that you want to place in their own m-files, and you only want test.m to have access to them, you would first create a subdirectory in \MATLAB\temp\ called private. Then, put the individual local function m-files from test.m in this private subdirectory.
The private subdirectory doesn't need to be added to the MATLAB path (in fact, it shouldn't be added to the path for things to work properly). Only the file test.m and other m-files in the directory immediately above the private subdirectory have access to the functions it contains. Using private functions, you can effectively emulate the behavior of local functions (i.e. limited scope, function overloading, etc.) without having to put all the functions in the same m-file (which can get very big for some applications).
Maybe something like this,
function foobar
addpath C:\Include\ModuleX
%% Script file residing in ModuleX
some_func();
end
Of course, ModuleX will remain in your search path after exiting foobar. If you want to set it to the default path without restarting, then add this line:
path(pathdef)
See ADDPATH for more details.
You can use sub-folders that begin with "+" to separate functions into namespaces.
For example:
Place a function "bar" in the folder "+foo"
function bar()
print('hello world');
This function can be used as:
foo.bar() % prints hello world
More information can be found here:
What is the closest thing MATLAB has to namespaces?
Related
Where can i save my document "function.m", so i can call this function from any code in any path of my pc?
I already made some custom functions, but i dont know where to save those codes to be able to call them from any part.
Save them in a logical place where you can find them back. Then, use addpath to add that folder to MATLAB's search path, i.e. when you use a function it will try that folder as well to find it.
You can do this either per script, or edit startup.m with this, so that it's automatically included when MATLAB starts.
Alternatively to Adriaan's best practice answer, the fastest option is to save your function.m in the %USERPROFILE%/Documents/MATLAB directory on your PC ($home/Documents/MATLAB on Linux and Mac). This directory is on your MATLAB Search Path by default. This might be an acceptable solution if you use the function commonly across different projects.
Finally, there is a "manual" solution: Execute pathtool in MATLAB, add the directory containing your function.m via the GUI and hit save.
I have many small functions in matlab, is it possible to put them all in one file so my work will look clearer?
i tried writing a small script and then adding the functions but is didn't work
any idea on how do do it?
It is not possible to have several functions in one file, because the function is accessed via the file name. That is why a function has to have the same name as the file name.
If you only access the "small" functions inside one other function, then you can put the small functions in the file of the other function, but then they are only accessible to this one function. This is called local functions in MATLAB. For example you have a file test.m with:
function x=test(y,z)
x = add(y,z)
end
function a=add(b,c)
a = b + c;
end
You can then only use add inside test, but you can use test just as usual.
What I usually do is put functions in subfolders. This helps you keep your path clean without any limitations. This also allows you to capsule your software better. The only thing you have to do is add the folder to your path with
addpath('subfolder');
If you have a function file, you can add other functions in that file.
If you have a script, you cannot add functions to it.
Note that if you put a function in a file, you cannot access the functions directly from outside your 'main' function scope.
In general I would recommend the use of folders, or proper file names to organize your functions, not stacking many of them in one file.
Extra
If your functions are really small and trivial, you could write a script with the declaration of anonymous functions for easy reuse. However this is probably not what you want.
I have created a few general function in MATLAB that I intend to use for a few separate projects. However I do not want to copy the function into each separate project function.
I have created a folder called Misc_Function when I have placed these general functions. I know I can reference this functions explicitly by using the path and function name when trying to call the functions.
I believe you can add a path (in my case 'H:\MyTeam\Matlab\Misc_Function') when MATLAB loads up is that correct and if so how do you do this?
Assuming the above can be done I'm interested to know how MATLAB finds the correct function. In my understanding (guess work) MATLAB has a list of paths that it check trying to find a function with the name specified - is that correct? If so what happens when there are functions with the same name?
MATLAB indeed has its own search path which is a collection of folders that MATLAB will search when you reference a function or class (and a few other things). To see the search path, type path at the MATLAB prompt. From the documentation:
The order of folders on the search path is important. When files with the same name appear in multiple folders on the search path, MATLAB uses the one found in the folder nearest to the top of the search path.
If you have a set of utility functions that you want to make available to your projects, add the folder to the top of the search path with the addpath function, like so
addpath('H:\MyTeam\Matlab\Misc_Function');
You have to do this everytime you start MATLAB. Alternatively, and more conveniently, save the current search path with the savepath command or add the above commands to your startup.m file.
You can check the actual paths where Matlab searches for functions using
path
You will notice, that the most top path (on start up) is a path in your home folder. For Linux this is e.g. /home/$USER/Documents/MATLAB. For Windows it is somewhere in the the c:\Users\%USER%\Documents\Matlab (I think). Placing a file startup.m in this folder allows to add additional paths using
addpath('H:\MyTeam\Matlab\Misc_Function');
or
addpath(genpath('H:\MyTeam\Matlab\Misc_Function'));
on start up of Matlab. The latter (genpath) allows to also add all subdirectories. Simply write a file startup.m and add one of above lines there.
I believe 'addpath' will add the folder to MATLAB path only for the current MATLAB session. To save the updated path for other sessions, you need to execute 'savepath' command.
As mentioned in the previous comments, adding the folder in startup.m is a good idea since it will be added to the path on MATLAB startup.
To answer your question about how MATLAB finds the correct function, MATLAB maintains a list of directories in its path in a file called pathdef.m. Any changes to the path will be written to this file (when you execute 'savepath'). The path variable is initialized with the contents of this file.
Tried Googling, but couldn't find anything.
I have a few files and folders in my current MATLAB folder.
One of those folders is called 'Map' and it has a 'map1.m' file which I want to call from my code in the current MATLAB folder.
In my code, I can't call it like this:
/Map/map1;
but I can do so like this:
cd Map;
map1;
cd ..;
Somehow the above method seems incorrect. Is there a more elegant way to do it?
You can run the file without adding the folder to your path manually, using the run command, which is specifically for such cases. From the documentation:
run is a convenience function that runs scripts that are not currently on the path.
You call your function/script as
run /Map/map1
If you want to run the function/script by merely entering its name and not with the full (or relative) path, then you should add the folder to your path.
As noted by #mutzmatron, you cannot use run to call functions with input/output arguments. So, unless if it's a script/function without input/output arguments, using run will not work and you'll have to add the folder to your path.
EDIT
Just as a matter of good coding practice, and to work in cases where your function has inputs/outputs, adding/removing the folder from your path is the correct way to go. So for your case,
addpath /Map
...
map1;
...
rmpath /Map
The important thing is that your function call is sandwiched between the addpath and rmpath commands. If you have functions of the same name in both folders, then you should sandwich it tighter i.e., a line before and a line after, so as to avoid conflicts.
Just add all those directories to the Matlab path with addpath like gnovice suggests. Then you'll be able to call the functions normally, and they'll be visible to which(), help(), depfun(), and the other Matlab meta-programming commands. You can put the addpath() calls in your startup.m file to have them automatically appear each time you start Matlab.
Changing the path with addpath/map1()/rmpath each time has some drawbacks.
It's a performance hit because you're adding path manipulation to each call.
Functions in different directories won't be able to see each other.
It'll be harder to write and debug functions because the path context in which they execute will change dynamically, and won't be the same as what you see when you're in the editor and the base workspace.
You need additional error handling code to make sure the path is properly restored if the called function errors out.
This won't work with the Matlab Compiler, if you want to deploy this code at some point.
And using run() or cd() yourself is ugly, because relative paths are going to have problems.
If you really want to separate the functions in the subdirectories so they can't "see" each other, you can make those directories namespaces by putting a "+" in front of their names, and then qualify the function calls with the namespace, like Map.map1().
Just to contribute to the path-altering debate...
One way to make it a bit "safer" is to write
% start of my code: create function handles
% to the functions I need:
try
cd Map
map1_func = #map1;
catch mexception
end
cd ..
This tries to preserve the current directory, and you get a handle to the function in a different directory.
Only thing is, this method won't work if map1 relies upon other functions in the Map directory.
I'm a total newbie to MATLAB but I have to write some code in it. I've had problems with making MATLAB see functions I've defined in external .m files. This is what I've done: I've created a file named, say, foo.m in my home dir with the following contents:
function [y] = foo(x)
% description
y = x + 1
When I run matlab (my home dir is matlab's workdir) it does not see foo function - it replies with standard ??? Undefined function or variable 'foo' message. BUT help foo or which foo return correct data printing help text and pointing on foo.m file respectively.
I must be missing something but I have no idea what it is. This is getting very annoying.
Oh, after several trial and error attempts I've managed to call that function. Unfortunately I can't remember the sequence of steps I've performed. Moreover after restarting matlab it returns to its usual 'Undefined function or variable' response.
I have 7.11.0.584 matlab running on linux.
MATLAB needs to be told which directories to search over to access those m-files. Clearly it cannot be left to search over your entire disk drives. The MATLAB search path is a list of directories that will be searched in specific order to find your functions.
help addpath
help pathtool
You should never put those files anywhere in the official MATLAB toolbox directories. Choose an entirely separate directory.
Finally, be careful not to name your own functions to match the names of existing MATLAB functions. Otherwise, your very next question here will be why your code does not work properly. This is a common cause of strange and confusing bugs.
It seems you're having some trouble with addpath. Try opening the file in the matlab editor and adding a break point in the file. If the file is not on Matlab's path, matlab should ask if you want to change directory or add the file to the path, choose add to the path.
If this doesn't work, try changing the current working directory (displayed in the main window) to the same location as the m file and calling the function. If this doesn't work you're either getting the name wrong ar there's possibly something wrong with your installation.
Occasionally matlab has problems if it does not have write permission to the directory the file's in, so check that too, i.e. make sure admin rights aren't required for the directory or m file.
Oh, and try:
clear functions
to reload all functions into memory.
The function needs to be in MATLAB's path. Use pathtool to tell MATLAB where to find your function. Note that if you name a function the same name as an existing function, MATLAB will use whichever function it finds first according to the order that the paths are listed as you see them in pathtool.
Although coming late but I hope it will help someone.
If in the folder where the function you are calling is residing, there is any other function with the same name as one of the functions from MATLAB toolboxes, then Matlab will not recognize its license and therefore will disable the whole folder from execution, no matter it is properly added to the path. The help will display though.
In order to check it, type:
which name_of_func.m
and you will get the path with "%Has no license available" message.
If it is your own function, you should not get this message but only the path.
Therefore, find the function in this folder which has the same name as a MATLAB toolbox functions, and rename it. I will solve the problem :).
Best Regards
Wajahat