Given a function, is there a way to extract the tensorflow variables that are used in it? (The framework must somehow do this when a function is passed to an optimizer)
I cannot understand what you say exactly.
But If you are talking about getting value from tensor, there are some ways to do that.
tensor.data() and tensor.dataSync()
Reference:
https://js.tensorflow.org/api/0.11.2/#tf.Tensor.data
Related
My question lies in the following code. Though the code is not working now. I wan't to rewrite it in proper way so that it works.
<span ng-if="community = vm.getCommunity(invite.community_id)!=null" grv-icon-comm-type="vm.communityViewHelper.getTypeIcon(community)" ng-class="vm.communityViewHelper.getColorClass(community)"></span>
In the above code vm.getCommunity(invite.community_id) returns either null or community object. If community object is returned then I wish to call two more function in the same element where I wish to use the recently receivedcommunity value on those two function.
It's just killing my time. Please help.
Alternatively, you could use a watcher on "invite.community_id" to set community inside a controller function. Could look a bit cleaner depending on the rest of the code.
This function could even set all three values if you like.
Say I have an external library that computes the optima, say minima, of a given function. Say its headers give me a function
double[] minimizer(ObjFun f)
where the headers define
typedef double (*ObjFun)(double x[])
and "minimizer" returns the minima of the function f of, say, a two dimensional vector x.
Now, I want to use this to minimize a parameterized function. I don't know how to express this in code exactly, but say if I am minimizing quadratic forms (just a silly example, I know these have closed form minima)
double quadraticForm(double x[]) {
return x[0]*x[0]*q11 + 2*x[0]*x[1]*q12 + x[1]*x[1]*q22
}
which is parameterized by the constants (q11, q12, q22). I want to write code where the user can input (q11, q12, q22) at runtime, I can generate a function to give to the library as a callback, and return the optima.
What is the recommended way to do this in C?
I am rusty with C, so asking about both feasibility and best practices. Really I am trying to solve this using C/Cython code. I was using python bindings to the library so far and using "inner functions" it was really obvious how to do this in python:
def getFunction(q11, q12, q22):
def f(x):
return x[0]*x[0]*q11 + 2*x[0]*x[1]*q12 + x[1]*x[1]*q22
return f
// now submit getFunction(/*user params*/) to the library
I am trying to figure out the C construct so that I can be better informed in creating a Cython equivalent.
The header defines the prototype of a function which can be used as a callback. I am assuming that you can't/won't change that header.
If your function has more parameters, they cannot be filled by the call.
Your function therefor cannot be called as callback, to avoid undefined behaviour or bogus values in parameters.
The function therefor cannot be given as callback; not with additional parameters.
Above means you need to drop the idea of "parameterizing" your function.
Your actual goal is to somehow allow the constants/coefficients to be changed during runtime.
Find a different way of doing that. Think of "dynamic configuration" instead of "parameterizing".
I.e. the function does not always expect those values at each call. It just has access to them.
(This suggests the configuration values are less often changed than the function is called, but does not require it.)
How:
I only can think of one simple way and it is pretty ugly and vulnerable (e.g. due to racing conditions, concurrent access, reentrance; you name it, it will hurt you ...):
Introduce a set of global variables, or better one struct-variable, for readability. (See recommendation below for "file-global" instead of "global".)
Set them at runtime to the desired values, using a separate function.
Initialise them to meaningful defaults, in case they never get written.
Read them at the start of the minimizing callback function.
Recommendation: Have everything (the minimizing function, the configuration variable and the function which sets the configuration at runtime) in one code file and make the configuration variable(s) static (i.e. restricts access to it this code file).
Note:
The answer is only the analysis that and why you should not try paraemeters.
The proposed method is not considered part of the answer; it is more simple than good.
I invite more holistic answers, which propose safer implementation.
I started learning C in class and have started the assignment but I'm writing it one piece at a time. Currently I'm stuck because I may be doing something completely wrong but I don't know what I'm doing.
The error is pretty clear... The void type isn't something you can return / store in a variable. Instead it's a special type that means "nothing". You can't store nothing, you must ignore the return or return something.
displayCard only displays the cards, it does nothing to define them, so you shouldn't be trying to use it to create your cards. Instead, think about what a "card" actually is in your program--what, for example, do you have to pass to displayCard in order for it to know which card to display?
As far as I know assigning this to a variable is used within callbacks where the this scope may change. But digging through the ExtJS source I found it used in all sorts of functions but not always. So is there any reason that I would assign this to a local variable beneath the scope or is the ExtJS source just struggling with different developer styles?
#kevhender pointed me to the right sencha forum thread where evan has given a very good explanation.
It's only for the size. And here's a example:
function doA() {
var me = this;
me.a();
me.b();
me.c();
me.d();
me.e();
me.f();
me.g();
me.h();
me.i();
me.j();
me.k();
me.l();
}
function doB() {
this.a();
this.b();
this.c();
this.d();
this.e();
this.f();
this.g();
this.h();
this.i();
this.j();
this.k();
this.l();
}
Compressed we get:
function doA(){var a=this;a.a();a.b();a.c();a.d();a.e();a.f();a.g();a.h();a.i();a.j();a.k();a.l()}
function doB(){this.a();this.b();this.c();this.d();this.e();this.f();this.g();this.h();this.i();this.j();this.k();this.l()};
It adds up.
According to that we should
NOT use a local var if we use this only up to three times
function doA(){var a=this;a.a();a.b();a.c();};
function doB(){this.a();this.b();this.c();};
and use it if we use this more often then three times
function doA(){var a=this;a.a();a.b();a.c();a.d()};
function doB(){this.a();this.b();this.c();this.d()};
There are a few reasons for this, the most significant being that using a local variable will save a few bytes during compression of the files. It may not seem like much for a small bit of code, but it can add up a good bit over time.
There is a long thread at the Sencha forums talking about this very issue: http://www.sencha.com/forum/showthread.php?132045.
As you've correctly stated this is sometimes used in places where the scope might change.
There are cases where you want to do the same to make sure there are no scoping issues.
Other than that, the devs sometimes just assign this to a variable out of habit more than out of necessity.
I only wanted to allow one instance of my C extension class to be made, so I wanted to include the singleton module.
void Init_mousetest() {
VALUE mouseclass = rb_define_class("MyMouse",rb_cObject);
rb_require("singleton");
VALUE singletonmodule = rb_const_get(rb_cObject,rb_intern("Singleton"));
rb_include_module(mouseclass,singletonmodule);
rb_funcall(singletonmodule,rb_intern("included"),1,mouseclass);
### ^ Why do I need this line here?
rb_define_method(mouseclass,"run",method_run,0);
rb_define_method(mouseclass,"spawn",method_spawn,0);
rb_define_method(mouseclass,"stop",method_stop,0);
}
As I understand it, what that line does is the same as Singleton.included(MyMouse), but if I try to invoke that, I get
irb(main):006:0> Singleton.included(MyMouse)
NoMethodError: private method `included' called for Singleton:Module
from (irb):6
from C:/Ruby19/bin/irb:12:in `<main>'
Why does rb_include_module behave differently than I would expect it to? Also any tangential discussions/explanations or related articles are appreciated. Ruby beginner here.
Also it seems like I could have just kept my extension as simple as possible and just hack some kind of interface later on to ensure I only allow one instance. Or just put my mouse related methods into a module... Any of that make sense?
according to http://www.groupsrv.com/computers/about105620.html the rb_include_module() is actually just Module#append_features.
Apparently Module#include calls Module#append_features and Module#included. So in our C code we must also call included. Since clearly something important happens there.