Structures with multiple, conntected anonymous functions
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I have a rather complicated workflow, however, I am having trouble identifying a way for it to work.
I start with a json of the form:
{
"x":3,
"y":6,
"fx":"@(a) a^2+y",
"fy":"@(a,b) y*fy(b)+b*x"
}
This gets read in and evaluated such that:
S.x = 3
S.y = 6
S.fx = @(a) a^2+y
S.fy = @(a,b) y*f(b)+b*x
I have tried both eval and str2funct to create the anonymous function.
Later in the workflow, this structure gets packaged into another structure
dS.S = S;
This is to help with passing a model around between functions.
The problem is, that later on, this command will give an error:
dS.S.fy(1,1)
The error states that the function fx cannot be found. However,
dS.S.fx(1)
does work, WITHOUT there being an "y" defined in the workspace.
Can anyone shed some light on this?
采纳的回答
Ameer Hamza
2020-5-13
编辑:Ameer Hamza
2020-5-13
Ok. I know "eval is evil" but here it makes everything quite simple in this case. You can define a helper function like this
function s = helperFun(s)
names = fieldnames(s);
for i=1:numel(names)
eval(sprintf('%s=s.%s;', names{i}, names{i}));
end
for i=1:numel(names)
if ischar(s.(names{i}))
s.(names{i}) = eval(s.(names{i}));
end
end
end
and then call it on your json file like this
S = jsondecode(fileread('test.txt'));
S = helperFun(S)
ds.S = S;
Then call the functions
>> ds.S.fx(1)
ans =
7
>> ds.S.fy(1, 2)
ans =
246
更多回答(1 个)
the cyclist
2020-5-13
Are you sure that y didn't exist in the workspace when you defined the structures? Because in a fresh workspace,
S.x = 3
S.y = 6
S.fx = @(a) a^2+y
S.fy = @(a,b) y*f(b)+b*x
dS.S = S
dS.S.fx(1)
gives the error
Unrecognized function or variable 'y'.
Error in @(a)a^2+y
Does that shed light?
9 个评论
James Tursa
2020-5-13
Yes, it appears you understand how function handles work now. Your current approach seems correct to me.
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