I want to remove hyphens (-), slashes (/) and white space () from a string name(i) so that I can use it as a structure field name.
This is the ugly way I am currently doing it using the function strrep:
cell2mat(strrep(strrep(strrep(name(i), '-',''),'/',''),' ', ''))
I have also tried other variations, such as:
strrep(name(i),{'-','/'},{'',''});
strrep(name(i),['-','/'],['','']);
What is a more efficient way of doing this?
Note: I'm guessing your variable name is a cell array of strings, in which case you will want to use {} (i.e. content indexing) instead of () (i.e. cell indexing) to get the strings from it...
As with many problems in MATLAB, there are a number of different ways you can solve this...
Option 1: You could use the function REGEXPREP. The following removes hyphens, forward slashes, and whitespace:
newName = regexprep(name{i},'[-/\s]','');
The benefit here is that the \s will match and replace all whitespace characters, which includes a normal space (ASCII code 32) as well as tabs, newlines, etc..
If you want to be safe and remove every character that is not valid in a MATLAB variable/field name, you can simplify the above to this:
newName = regexprep(name{i},'\W','');
Option 2: If you don't need to worry about removing anything other than the 3 characters you listed, you could use the function ISMEMBER like so:
newName = name{i};
newName(ismember(newName,'-/ ')) = [];
Option 3: If you want to just keep everything that is an alphanumeric character and dump the rest (hyphens, whitespace, underscores, etc.), you could use the function ISSTRPROP:
newName = name{i};
newName = newName(isstrprop(newName,'alphanum'));
The easiest way is to use the built in function genvarname. It will make the name look uglier, but its guaranteed to be a valid name AND it will retain you original uniqueness.
If you just want to remove specific characters, you can use regexprep:
regexprep('foo- /foo- /foo', '[- \/]', '')
genvarname is the correct solution to the overall problem. Regular expressions, however, are a heavyweight solution to a simple problem.
Strings are just arrays, so you could do something like:
name(name == '-' | name == '/' | name = ' ') = [];
With respect to your overall goal, there are many more characters that aren't valid in a struct name. You're bet off defining a set of allowable characters, and eliminating everything that isn't in that set.
e.g.:
function i = isAllowed(str)
i = (str >= '0' & str <= '9') ...
| (str >= 'a' & str <= 'z') ...
| (str >= 'A' & str <= 'Z');
...
name(~isAllowed(name)) = [];
Here's another solution:
name = 'some/path/file-name ext'; %# sample string
blacklist = {'-' '/' ' '}; %# list of character not allowed
idx = cell2mat( cellfun(@(c)strfind(name,c), blacklist, 'UniformOutput',false) );
name(idx) = '_'; %# you can remove/replace those locations
>> name
name =
some_path_file_name_ext
