I will run a set of experiments. The main method evaluated has the following signature:
[Model threshold] = detect(...
TrainNeg, TrainPos, nf, nT, factors, ...
removeEachStage, applyEstEachStage, removeFeatures);
where removeEachStage, applyEstEachStage, and removeFeatures are booleans. You can see that if I reverse the order of any of these boolean parameters I may get wrong results.
Is there a method in MATLAB that allows better organization in order to minimize this kind of error? Or is there any tool I can use to protect me against these errors?
Organization with a struct
You could input a struct that has these parameters as it's fields.
For example a structure with fields
setts.TrainNeg
.TrainPos
.nf
.nT
.factors
.removeEachStage
.applyEstEachStage
.removeFeatures
That way when you set the fields it is clear what the field is, unlike a function call where you have to remember the order of the parameters.
Then your function call becomes
[Model threshold] = detect(setts);
and your function definition would be something like
function [model, threshold] = detect(setts)
Then simply replace the occurrences of e.g. param with setts.param.
Mixed approach
You can also mix this approach with your current one if you prefer, e.g.
[Model threshold] = detect(in1, in2, setts);
if you wanted to still explicitly include in1 and in2, and bundle the rest into setts.
OOP approach
Another option is to turn detect into a class. The benefit to this is that a detect object would then have member variables with fixed names, as opposed to structs where if you make a typo when setting a field you just create a new field with the misspelled name.
For example
classdef detect()
properties
TrainNeg = [];
TrainPos = [];
nf = [];
nT = [];
factors = [];
removeEachStage = [];
applyEstEachStage = [];
removeFeatures =[];
end
methods
function run(self)
% Put the old detect code in here, use e.g. self.TrainNeg to access member variables (aka properties)
end
end
Related
In WebhookScript, I can store a function in a variable with:
sub = function(a, b) {
return a - b
}
I'd like to store a function in a Global Variable so that I can use it in multiple Custom Actions. But if I've saved the above function as $sub$ then
sub2 = var('$sub$')
subX = sub(1,2)
causes an error:
Trying to invoke a non-function 'string' # line...
And
function subX(a,b){
var('$sub$')
}
when sub only contains return a - b, doesn't work either.
Obviously I need to convert the string to a function but I'm not sure whether that's possible.
I know this is a bit of an obscure language but if anyone knows how this can be done in similar languages like JavaScript and PHP, I'm happy to test out any guesses...
The solution here is to remove the function section and just enter the script, which inherits the execution scope so if my global variable $script$ is:
return 'hello ' + a
Then I can execute the function with:
a = 'world'
value = exec(var('$script$'))
echo(value)
(credit to Webhook.Site's support team for explaining this)
I need an example on how to paramtrize Vector of registers in terms of bit-width and initial values which are not '0' and are different for each register.
My use-case is a generic filter coefficients bank with some unique reset values to each, and off course an option to override values.
I thought of something like the below code (not really sure how to write the iteration, so this is kind of pseudo):
class Coeffbank(bitWidth : UInt ,ncoeff : UInt, rstVal : Vec(SInt)) extends Module {
// how do iterate through the reset vector ?? //
val coeffs = Vec.fill(ncoeff) {Reg(init = SInt(rstVal(i),width = bitwidth))
}
Also, when new'ing the above (instantiating this module how do I pass the list of reset value in the argument list?
Hoping to get some help on how to write it properly.
The explanation should probably be a bit more thorough, but basically you need to create a Reg of Vec. Something like should do it:
val coeffs = RegInit(rstVal)
In this case, since you already have the Vec of reset values, you can just pass it to the Reg constructor.
I'm assuming that the size of rstVal is equal to ncoeff, otherwise you'll need to reduce the size of rstVal with something like rstVal.take(ncoeff). Also note that I'm using RegInit which is the preferred way to create a register with a reset value.
Let's start with the easy case. This would be much easier if instead of a Vec of SInts your rstVal array was instead a scala collection (Seq, Array, ...) of regular SInt. When possible it is best to save generation of actual hardware until you directly need them. If rstVal contains Int's. Your code would become
val newRstVals = VecInit(Seq.tabulate(ncoeff) { index => rstVals(index).S(bitWidth.W) })
val reg = RegInit(newRstVals)
If you really need to pass in a Vec then the right approach is to create a separate type instance and use the two argument call to RegInit
val vecType = Vec(ncoeff, SInt(bitWidth.W))
val newRstVals1 = VecInit(Seq.tabulate(ncoeff) { index => newRstVals(index) })
val reg = RegInit(vecType, newRstVals1)
There might be problems if the bitWidth you pass in is not big enough to contain the constants you have passed in. You probably should have some checks for that.
Is there any way to initialize a Sequential value not in one fellow swoop?
Like, can I declare it, then use a for loop to populate it, step by step?
As this could all happen inside a class body, the true immutability of the Sequential value could then kick in once the class instance construction phase has been completed.
Example:
Sequential<String> strSeq;
for (i in span(0,10)) {
strSeq[i] = "hello";
}
This code doesn't work, as I get this error:
Error:(12, 9) ceylon: illegal receiving type for index expression:
'Sequential' is not a subtype of 'KeyedCorrespondenceMutator' or
'IndexedCorrespondenceMutator'
So what I can conclude is that sequences must be assigned in one statement, right?
Yes, several language guarantees hinge on the immutability of sequential objects, so that immutability must be guaranteed by the language – it can’t just trust you that you won’t mutate it after the initialization is done :)
Typically, what you do in this situation is construct some sort of collection (e. g. an ArrayList from ceylon.collection), mutate it however you want, and then take its .sequence() when you’re done.
Your specific case can also be written as a comprehension in a sequential literal:
String[] strSeq = [for (i in 0..10) "hello"];
The square brackets used to create a sequence literal accept not only a comma-separated list of values, but also a for-comprehension:
String[] strSeq = [for (i in 0..10) "hello"];
You can also do both at the same time, as long as the for-comprehension comes last:
String[] strSeq = ["hello", "hello", for (i in 0..8) "hello"];
In this specific case, you could also do this:
String[] strSeq = ["hello"].repeat(11);
You can also get a sequence of sequences via nesting:
String[][] strSeqSeq = [for (i in 0..2) [for (j in 0..2) "hello"]];
And you can do the cartesian product (notice that the nested for-comprehension here isn't in square brackets):
[Integer, Character][] pairs = [for (i in 0..2) for (j in "abc") [i, j]];
Foo[] is an abbreviation for Sequential<Foo>, and x..y translates to span(x, y).
If you know upfront the size of the sequence you want to create, then a very efficient way is to use an Array:
value array = Array.ofSize(11, "");
for (i in 0:11) {
array[i] = "hello";
}
String[] strSeq = array.sequence();
On the other hand, if you don't know the size upfront, then, as described by Lucas, you need to use either:
a comprehension, or
some sort of growable array, like ArrayList.
I've been learning lua and can't seem to make a simple implementation of this binary tree work...
function createTree(tree, max)
if max > 0 then
tree = {data = max, left = {}, right = {}}
createTree(tree.left, max - 1)
createTree(tree.right, max - 1)
end
end
function printTree(tree)
if tree then
print(tree.data)
printTree(tree.left)
printTree(tree.right)
end
end
tree = {}
createTree(tree, 3)
printTree(tree)
the program just returns nil after execution. I've searched around the web to understand how argument passing works in lua (if it is by reference or by value) and found out that some types are passed by reference (like tables and functions) while others by value. Still, I made the global variable "tree" a table before passing it to the "createTree" function, and I even initialized "left" and "right" to be empty tables inside of "createTree" for the same purpose. What am I doing wrong?
It is probably necessary to initialize not by a new table, but only to set its values.
function createTree(tree, max)
if max > 0 then
tree.data = max
tree.left = {}
tree.right = {}
createTree(tree.left, max - 1)
createTree(tree.right, max - 1)
end
end
in Lua, arguments are passed by value. Assigning to an argument does not change the original variable.
Try this:
function createTree(max)
if max == 0 then
return nil
else
return {data = max, left = createTree(max-1), right = createTree(max-1)}
end
end
It is safe to think that for the most of the cases lua passes arguments by value. But for any object other than a number (numbers aren't objects actually), the "value" is actually a pointer to the said object.
When you do something like a={1,2,3} or b="asda" the values on the right are allocated somewhere dynamically, and a and b only get addresses of those. Thus, when you pass a to the function fun(a), the pointer is copied to a new variable inside function, but the a itself is unaffected:
function fun(p)
--p stores address of the same object, but `p` is not `a`
p[1]=3--by using the address you can
p[4]=1--alter the contents of the object
p[2]=nil--this will be seen outside
q={}
p={}--here you assign address of another object to the pointer
p=q--(here too)
end
Functions are also represented by pointers to them, you can use debug library to tinker with function object (change upvalues for example), this may affect how function executes, but, once again, you can not change where external references are pointing.
Strings are immutable objects, you can pass them around, there is a library that does stuff to them, but all the functions in that library return new string. So once, again external variable b from b="asda" would not be affected if you tried to do something with "asda" string inside the function.
At the beginning of a method I want to check if the method is called with these exact parameters before, and if so, return the result that was returned back then.
At first, with one parameter, I used a Dictionary, but now I need to check 3 parameters (a String, an Object and a boolean).
I tried making a custom Object like so:
var cacheKey:Object = { identifier:identifier, type:type, someBoolean:someBoolean };
//if key already exists, return it (not working)
if (resultCache[cacheKey]) return resultCache[cacheKey];
//else: create result ...
//and save it in the cache
resultCache[cacheKey] = result;
But this doesn't work, because the seccond time the function is called, the new cacheKey is not the same object as the first, even though it's properties are the same.
So my question is: is there a datatype that will check the properties of the object used as key for a matching key?
And what else is my best option? Create a cache for the keys as well? :/
Note there are two aspects to the technical solution: equality comparison and indexing.
The Cliff Notes version:
It's easy to do custom equality comparison
In order to perform indexing, you need to know more than whether one object is equal to another -- you need to know which is object is "bigger" than the other.
If all of your properties are primitives you should squash them into a single string and use an Object to keep track of them (NOT a Dictionary).
If you need to compare some of the individual properties for reference equality you're going to have a write a function to determine which set of properties is bigger than the other, and then make your own collection class that uses the output of the comparison function to implement its own a binary search tree based indexing.
If the number of unique sets of arguments is in the several hundreds or less AND you do need reference comparison for your Object argument, just use an Array and the some method to do a naive comparison to all cached keys. Only you know how expensive your actual method is, so it's up to you to decide what lookup cost (which depends on the number of unique arguments provided to the function) is acceptable.
Equality comparison
To address equality comparison it is easy enough to write some code to compare objects for the values of their properties, rather than for reference equality. The following function enforces strict set comparison, so that both objects must contain exactly the same properties (no additional properties on either object allowed) with the same values:
public static propsEqual(obj1:Object, obj2:Object):Boolean {
for(key1:* in obj1) {
if(obj2[key1] === undefined)
return false;
if(obj2[key1] != obj2[key1])
return false;
}
for(key2:* in obj2)
if(obj1[key2] === undefined)
return false;
return true;
}
You could speed it up by eliminating the second for loop with the tradeoff that {A:1, B:2} will be deemed equal to {A:1, B:2, C:'An extra property'}.
Indexing
The problem with this in your case is that you lose the indexing that a Dictionary provides for reference equality or that an Object provides for string keys. You would have to compare each new set of function arguments to the entire list of previously seen arguments, such as using Array.some. I use the field currentArgs and the method to avoid generating a new closure every time.
private var cachedArgs:Array = [];
private var currentArgs:Object;
function yourMethod(stringArg:String, objArg:Object, boolArg:Boolean):* {
currentArgs = { stringArg:stringArg, objArg:objArg, boolArg:boolArg };
var iveSeenThisBefore:Boolean = cachedArgs.some(compareToCurrent);
if(!iveSeenThisBefore)
cachedArgs.push(currentArgs);
}
function compareToCurrent(obj:Object):Boolean {
return someUtil.propsEqual(obj, currentArgs);
}
This means comparison will be O(n) time, where n is the ever increasing number of unique sets of function arguments.
If all the arguments to your function are primitive, see the very similar question In AS3, where do you draw the line between Dictionary and ArrayCollection?. The title doesn't sound very similar but the solution in the accepted answer (yes I wrote it) addresses the exact same techinical issue -- using multiple primitive values as a single compound key. The basic gist in your case would be:
private var cachedArgs:Object = {};
function yourMethod(stringArg:String, objArg:Object, boolArg:Boolean):* {
var argKey:String = stringArg + objArg.toString() + (boolArg ? 'T' : 'F');
if(cachedArgs[argKey] === undefined)
cachedArgs[argKey] = _yourMethod(stringArg, objArg, boolArg);
return cachedArgs[argKey];
}
private function _yourMethod(stringArg:String, objArg:Object, boolArg:Boolean):* {
// Do stuff
return something;
}
If you really need to determine which reference is "bigger" than another (as the Dictionary does internally) you're going to have to wade into some ugly stuff, since Adobe has not yet provided any API to retrieve the "value" / "address" of a reference. The best thing I've found so far is this interesting hack: How can I get an instance's "memory location" in ActionScript?. Without doing a bunch of performance tests I don't know if using this hack to compare references will kill the advantages gained by binary search tree indexnig. Naturally it would depend on the number of keys.