How to bind a 2D array to a parameter in Solver Foundation? Have tried defining the array as double(,); as double()() and as a list of tuples(double, i, j).
I have also tried to implement the extension methods to SetBinding, suggested here; http://blogs.msdn.com/b/solverfoundation/archive/2010/06/28/simpler-data-binding-using-linq-and-extension-methods.aspx
Currently fails at third line to bottom; m_cov.SetBinding(CovMatrix), with error "This method is only valid when called on parameters with 0 indexes"
I'm using latest version and working in vb.net. Any help appreciated.
Thanks,
Yug
Public Sub ERC()
Dim m_i = New [Set](Domain.Any, "I")
Dim m_j = New [Set](Domain.Any, "J")
'Dim m_allocation As Decision
Dim CovMatrix As Double()() = {New Double() {0.1, 0.15, 0.4}, New Double() {0.3, 0.5, 0.8}, New Double() {0, 0.33, 0.05}}
Dim m_context As SolverContext = SolverContext.GetContext()
Dim m_model As Model = m_context.CreateModel()
m_model.Name = "ERC"
' Create a Parameter for Cov
Dim m_cov = New Parameter(Domain.Real, "Cov", m_i, m_j)
m_model.AddParameter(m_cov)
' Create a Decision for Allocation
Dim m_allocation As Decision = New Decision(Domain.RealRange(-1.0, 1.0), "Allocation", m_i)
m_model.AddDecision(m_allocation)
' Add Constraint for SumWts
m_model.AddConstraint("SumWts", (Model.Sum(Model.ForEach(m_i, Function(i_1) Model.Abs(Model.Sum(m_allocation(i_1)))))) = 1.0)
' Add Goal for Variance
m_model.AddGoal("Variance", GoalKind.Minimize, Model.Sum(Model.ForEach(m_i, Function(i_2) Model.ForEach(m_j, Function(j_3) Model.Power((Model.Abs(Model.Sum(Model.ForEach(m_j, Function(j_4) Model.Product(m_cov(i_2, j_4), m_allocation(j_4), m_allocation(i_2))))) - Model.Abs(Model.Sum(Model.ForEach(m_j, Function(j_6) Model.Product(m_cov(j_3, j_6), m_allocation(j_6), m_allocation(j_3)))))), 2.0)))))
m_cov.SetBinding(CovMatrix)
m_context.Solve()
Debug.Print(m_allocation.GetValuesByIndex().ToString)
End Sub
The helper class provided by Nathan Brixius makes SetBinding way easier. His helper class is in C#, so I went ahead and converted the particular helper function you will need into VB (see below).
The exception is telling you that the SetBinding function needs to know the indices for the data passed in. MSF is built to handle generic domains, meaning it does not abide by normal array indices. You have to explicitly point out the index information.
The problem with your code is that you are trying to pass in raw arrays without any extra index data. To remedy this on a normal 1D array, you would add indices using KeyValuePair(Of Integer, Double). In this case for a matrix you need a list of Tuple (index1, index2, Double). Essentially, you need to flatten the 3x3 matrix into 9 triples, specifying each value according to a pair of indices.
Here is the VB function to convert your matrix into a list as such:
Private Function ToIEnumerable(Of T)(matrix As IEnumerable(Of IEnumerable(Of T))) As IEnumerable(Of Tuple(Of Integer, Integer, T))
Dim m = matrix.[Select](Function(row, i) row.[Select](Function(cell, j) New Tuple(Of Integer, Integer, T)(i, j, cell)))
Dim cells = From cell In m.SelectMany(Function(c) c)
Return cells
End Function
Include this function in your class, and then change the SetBinding line of code like so:
m_cov.SetBinding(ToIEnumerable(CovMatrix), "Item3", "Item1", "Item2")
Notice the ordering of the Tuple items! By MSF convention, the value field comes before the indices. The same ordering is returned in the Solution output (important to note when you are looking to iterate over the Decisions on the result set).
If you convert the rest of Nathan's helper class, he makes it even easier by overloading the SetBinding function itself to abstract away the ToIEnumerable(data) call as well as the key/value identifier ordering. Then you are able to simply call model.SetBinding(rawMatrix).
Pretty slick, eh? ;)
Related
I've been stuck with this for a while and I couldn't find something similar asked previously (or I have failed in doing so)
My situation is fairly simple: I have a cell array of objects. They are all the same object and I have a get function for this kind of object which is: get (obj, attr), where obj is the object in question and attr is a integer from 1-6. Depending on the number the get function returns the corresponding attribute.
I would like to obtain all of my "position" attributes from all my objects which are in the corresponding cell array (this would be attr = 2). I know that cellfun performs a function on all cells, but the question is, how do I use my get function here for all my objects, taking into account that the function is get (obj, attr) ?
Thanks in advance
Firstly, by using get as a custom function you are shadowing the built-in get function - this is bad practise!
With this in mind, and to avoid confusion with the built-in get function which has similar syntax, I'm going to use getattr as a stand-in for your custom function which accpets an object and an integer 1 to 6.
pos = cellfun( #(obj) getattr( obj, 2 ), myCellOfObjects, 'uni', 0 );
By specifying 'uni', 0, the output doesn't have to be scalar and will be put into a cell array. This is useful when, for example, you have a multi-element array for your position.
This is equivalent to the following loop:
pos = cell( numel(myCellOfObjects), 1 );
for ii = 1:numel(pos)
pos{ii} = getattr( myCellOfObjects{ii}, 2 );
end
If ever in doubt about cellfun or arrayfun, just write a loop first - they are essentially the same but more concise.
There is a trick to this some are unaware of: you can pass multiple arguments to cellfun like this:
cellfun(#(obj,attr) get(obj,attr), {obj1,obj2},{attr1,attr2},'uni',0)
if you want to get one attribute of the cellarray (instead of providing an attribute for every object in the cellarray), then you can simply use this
cellfun(#(x) getattr(x,attr),obj,'uni',0)
put into anonymous function for convenience:
get_attr = #(obj,attr) cellfun(#(x) getattr(x,attr),obj,'uni',0)
%use:
get_attr(obj_in_cellarray,'myattribute')
%returns cell array of object attributes
I haven't run any of these functions since you didn't provide any example data / code. Please test and feedback.
For (MEX) function calls it would be really nice to pass several properties of one object at once. Instead of foo(myObj.propA, myObj.propB) I want something like foo(myObj.[propA,propB].
Is this even possible?
With structs it is possible to use the getfield() function to get the data from more than one field, e.g.:
getfield(myStruct, {index}, {'fieldA', 'fieldB'})
But unfortunately, the following attempt to get more than one property from an object results in an error (Index exceeds matrix dimensions):
getfield(myObj, {index}, {'propA', 'propB'})
Maybe the only possibility is to write a function which returns several output arguments:
[varargout] = getProps(object,propnames)
for p=1:numel(propnames)
varargout{p} = object.(propnames{p});
end
But if I call another function with that function as input, e.g. sum(getProps(myObj,propnames)) only the first output argument of getProps is passed and I fall into despair. Is there any other way?
For an object, you'd use get, not getfield (or dynamic access in a loop like you showed).
>> h = figure;
>> get(h,{'Position','Renderer'})
ans =
[1x4 double] 'opengl'
This doesn't work for all objects, but for MATLAB graphics objects it does work. To deal with any class, you can use your function, but with a custom cell output instead of varargout:
function C = getProps(object,propnames)
for p = 1:numel(propnames),
C{p} = object.(propnames{p});
end
Then inside whatever function you write, you can get a comma-separated list of all properties with C{:}, which will be suitable for a function that expects each property name input as a separate argument (e.g. C = getProps(myObj,propnames); x = myFun(h,C{:}).
I'm creating a game in a vba form. Right now it creates an array 9x9 of textboxes and fills and disables the textboxes with the given information for the game. When creating the textboxes I named them "fieldx-y" so I could look them up easily. I want to somehow put them into an array so that I can look them up like field(x,y) and then do things to them like change the background color of the textbox or change information in it.
Here is the function I wanted to use to find the object using its name and return it to be manipulated.
Public Function getField(x As Integer, y As Integer) As MSForms.TextBox
Dim field As MSForms.TextBox
For Each field In Me.Controls
If Right(field.Name, 1) = y And Left(Right(field.Name, 3), 1) = x Then
getField = field
End If
Next
End Function
And here is how I would like to manipulate it from my userform initialize sub
getField(5,5).Enabled=False
I'm sure I must be doing something very wrong and it's probably because of my lacking understanding of OOP and vba.
Thanks
Since you have chosen a predictable naming convention you can call these controls directly using your naming convention. There is no need to loop through all the controls. Also, I changed your fieldx-y to fieldx_y because - is an illegal character variable names.
Public Function getField(x As Integer, y As Integer) As MSForms.TextBox
set getField = me.controls("field" & x & "_" & y)
End Function
If all you are doing is enabling the control, then you may not actually need to return the textbox, in which case do not add the tb variable to the calling procedure, and change your function to a sub, like:
Public Sub getField(x As Integer, y As Integer)
Dim field As MSForms.TextBox
For Each field In Me.Controls
If Right(field.Name, 1) = y And Left(Right(field.Name, 3), 1) = x Then
'## Disable this textbox
field.Enabled = False
Exit For
End If
Next
End Sub
If you do need to return a textbox to the calling procedure, then do this:
In your calling procedure, you need an object variable to represent the returned MSForms.TextBox:
Dim tb as MSForms.TextBox
Set tb = getField(5,5)
tb.Enabled = False
Then in your function routine, because it is an object, you need the Set keyword:
Set getField = field
Exit For '## You need to escape the loop otherwise it will keep going, giving undesired results.
Writing a subclass of dynamicprops allows to me to add properties dynamically to an object:
addprop(obj, 'new_prop')
This is great, but I would also love to create set / get functions for these properties on the fly. Or analysis functions that work on these dynamic properties.
My experience with Matlab has been so far, that once I create an instance of a class, adding new methods is not possible. That is very cumbersome, because my object may contain a lot of data, which I'll have to re-load every time that I want to add a new method (because I have to do clear classes).
So is there a way to add methods on the fly?
You cannot add methods like you add dynamic properties. However, there are two ways for implementing new methods during development that won't require you to re-load the data every time.
(1) I write standard methods as separate functions, and call them as myMethod(obj) during development. Once I'm sure they're stable, I add their signature into the class definition file - this requires a clear classes, of course, but it is a much delayed one, and from time to time you may have to shut down Matlab, anyway.
(2) With set/get methods, things are a little trickier. If you are using dynamicprops to add new properties, you can also specify their set/get methods, however (most likely, these methods/functions will want to receive the name of the property so that they know what to refer to):
addprop(obj,'new_prop');
prop = findprop(obj,'new_prop');
prop.SetMethod = #(obj,val)yourCustomSetMethod(obj,val,'new_prop')
EDIT
(2.1) Here's an example of how to set up a hidden property to store and retrieve results (based on jmlopez' answer). Obviously this can be improved a lot if you have a better idea what you're actually designing
classdef myDynamicClass < dynamicprops
properties (Hidden)
name %# class name
store %# structure that stores the values of the dynamic properties
end
methods
function self = myDynamicClass(clsname, varargin)
% self = myDynamicClass(clsname, propname, type)
% here type is a handle to a basic datatype.
self.name_ = clsname;
for i=1:2:length(varargin)
key = varargin{i};
addprop(self, key);
prop = findprop(self, key);
prop.SetMethod = #(obj,val)myDynamicClass.setMethod(obj,val,key);
prop.GetMethod = #(obj)myDynamicClass.getMethod(obj,key);
end
end
function out = classname(self)
out = self.name_;
end
end
methods (Static, Hidden) %# you may want to put these in a separate fcn instead
function setMethod(self,val,key)
%# have a generic test, for example, force nonempty double
validateattributes(val,{'double'},{'nonempty'}); %# will error if not double or if empty
%# store
self.store.(key) = val;
end
function val = getMethod(self,key)
%# check whether the property exists already, return NaN otherwise
%# could also use this to load from file if the data is not supposed to be loaded on construction
if isfield(self.store,key)
val = self.store.(key);
else
val = NaN;
end
end
end
end
I'm adding this answer because I think that this is not intuitive. At least not to myself at this moment. After finding this question I thought I had what I needed to be able to define the set/get methods for my dynamic class. All I wanted to achieve with this was something similar to what python does with its __setattr__ method. In any case, here is a continuation of the class made by #jonas a while ago with a few modifications to add the our custom set method.
classdef myDynamicClass < dynamicprops
properties (Hidden)
name_ %# class name
end
methods
function self = myDynamicClass(clsname, varargin)
% self = myDynamicClass(clsname, propname, type)
% here type is a handle to a basic datatype.
self.name_ = clsname;
for i=1:2:length(varargin)
key = varargin{i};
addprop(self, key);
prop = findprop(self, key);
prop.SetMethod = makefunc(key, varargin{i+1});
end
end
function out = classname(self)
out = self.name_;
end
end
end
function h = makefunc(key, argtype)
h = #newfunc;
function newfunc(obj, val)
obj.(key) = argtype(val);
end
end
With this class I'm defining the set method so that the parameter passed to the attribute is copied to the right type. To see what I mean consider the following usage:
>> p_int = myDynamicClass('Point', 'x', #int8, 'y', #int32);
>> p_int.x = 1000
p_int =
myDynamicClass with properties:
y: []
x: 127
>> class(p_int.x)
ans =
int8
With this we have forced the x attribute to be an integer of 8 bits which can only hold integers from -128 to 127. Also notice how the class of each attribute gives us the intended type.
My experience with Matlab has been so far, that once I create an instance of a class, adding new methods is not possible. That is very cumbersome, because my object may contain a lot of data, which I'll have to re-load everytime that I want to add a new method (because I have to do clear classes).
It's worth noting for present-day readers of this question that this is no longer true. As of MATLAB R2014b MATLAB updates class definitions at the moment you save them, and the behaviour of existing class instances automatically updates accordingly. In the case of adding new methods, this is uncomplicated: the new method simply becomes available to call on class instances even if they were created before the method was added to the class.
The solutions given for choosing set/get methods for dynamic properties still apply.
There are still cases where you might want to add methods to an instance dynamically and the method doesn't constitute a property set/get method. I think the only answer in this case is to assign a function handle as the value to a dynamic property. This doesn't create a bona fide method, but will allow you to call it in the same way you would a method call:
addprop(obj, 'new_method');
obj.new_method = #(varargin) my_method(obj,varargin{:});
Calls to obj.new_method(args) are thus passed to my_method; however this only works with a scalar obj; an array of instances will have separate values for the new_method property so obj.new_method no longer resolves to a single function handle that can be called if obj is an array.
How can i access the following structure path with dynamic fieldnames:
var = 'refxtree.CaseDefinition.FlowSheetObjects.MaterialStreamObjects{8}.MaterialStreamObjectParams.Pressure.Value.Text';
fields = textscan(var,'%s','Delimiter','.');
refxtree.(fields{:}) does not work because MaterialStreamObjects contains a cell array of which I want to access the 8th cell and then continue down the structure path.
In the end I want to get and set the fieldvalues.
You need to build the appropriate input to subsref, possibly using substruct. Look at the MATLAB help.
You can define an anonymous function to navigate this particular kind of structure of the form top.field1.field2.field3{item}.field4.field5.field6.field7 (as an aside: is it really necessary to have such a complicated structure?).
getField = #(top,fields,item)top.(fields{1}).(fields{2}).(fields{3}){item}.(fields{4}).(fields{5}).(fields{6}).(fields{7})
setField = #(top,fields,item,val)subsasgn(top.(fields{1}).(fields{2}).(fields{3}){item}.(fields{4}).(fields{5}).(fields{6}),struct('type','.','subs',fields{7}),val);
You use the functions by calling
fieldValue = getField(refxtree,fields,8);
setField(refxtree,fields,8,newFieldValue);
Note that fields is required to have seven elements. If you want to generalize the above, you will have to dynamically create the above functions
In this case, it is easier to just use EVAL:
str = 'refxtree.CaseDefinition.FlowSheetObjects.MaterialStreamObjects{8}.MaterialStreamObjectParams.Pressure.Value.Text';
%# get
x = eval(str)
%# set
evalc([str ' = 99']);