Provide variable argument list - matlab

Question

I have a function which accepts a variable number of input variables. The problem is, the number of input arguments I'm going to provide varies. As such, I store all the arguments in a structure:
function grandAvg(datafiles)
% Load up all averaged datafiles
avgs = struct();
for n=1:length(datafiles)
avgs(n).avg = load(datafiles{n});
end
My question is, is there a way to expand this argument for the function? I need a way to convert this:
% DOES NOT WORK
avg = ft_timelockgrandaverage(cfg, avgs);
to this:
% WOULD WORK, BUT DO NOT WANT TO TYPE IT OUT
avg = ft_timelockgrandaverage(cfg, avgs(1).avg, ..., avgs(n).avg);
EDIT TO ADD: So apparently my question wasn't clear. I know how to construct the function using varargin. My question was, if I am trying to use a build-in function which I don't want to or can't modify, how can I provide arguments in a variable manner? I.e., I don't know ahead of time how many argument's I'll be providing, so when I call the function, I'll have to call it with X number of arguments. In effect, I'm looking for a way to turn this:
someVar <1xN struct>
into this:
someVar1 <1x1 struct>
someVar2 <1x1 struct>
...
someVarN <1x1 struct>
in a programmatic manner. Thanks!

Answer 1

An alternative to using a structure array to store your data would be to use a cell array. For example:
nFiles = numel(datafiles); %# Number of files
avgs = cell(1,nFiles); %# Initialize an empty cell array
for iFile = 1:nFiles %# Loop over the files
avgs{iFile} = load(datafiles{iFile}); %# Load the data into each cell
end
avg = ft_timelockgrandaverage(cfg, avgs{:}); %# Pass the contents to a function
The syntax avgs{:} dumps the contents of the cell array into what's called a comma-separated list. It is equivalent to typing avgs{1}, avgs{2}, ... , avgs{end}. The syntax foo(:).bar from the answer you found also creates a comma-separated list, but I find that using cell arrays for such a purpose is generally cleaner than using a structure array.

Answer 2

yes you can use variable length input argument list
varargin
http://www.mathworks.com/help/techdoc/ref/varargin.html

Answer 3

So, after playing around, I've got it. Using the example from above:
Given an 1xN struct named foo, where each foo(n) contains the field bar, I would call the function as:
function(foo(:).bar);
This is the same as typing
function(foo(1).bar, foo(2).bar, ..., foo(N).bar);
In this way, I can dynamically expand or shrink foo and still have no problem calling the function.

Answer 4

You can surely do such a thing, by means of the varargin construct in MATLAB. This will be something like:
avg = ft_timelockgrandaverage(cfg, avgs.avg);
And for the function ft_timelockgrandaverage
function output = ft_timelockgrandaverage(config, varargin)
% your code here
varargin will be a cell array: {avgs(1).avg, avgs(2).avg, ..., avgs(3).avg} which you can process.