I want to make a bit array or bit vector of items I have in an array so that I can create a binary fingerprint to compare to an object's fingerprint.
Here is an example:
Base fingerprint...
All "available" colors
colorsArray[blue, red, white, green, orange];
Make this into a binary array (or whatever)
This is the result = masterPrint[1,1,1,1,1];
Now I have a separate object that has the colors red and blue in it (object[red,blue])
This object's fingerprint is object's print = [1,1,0,0,0];
Compare two prints, master print [1,1,1,1,1] and object print [1,1,0,0,0];
Result is two matches 40%
How can I accomplish this? Thank you
Better option is CFMutableBitVector
CFBitVector and its derived mutable type, CFMutableBitVector, manage ordered collections of bit values, which are either 0 or 1.
CFBitVector creates static bit vectors and CFMutableBitVector creates dynamic bit vectors.
See the class reference here
Related
I am new at Stan and I'm struggling to understand the difference in how different variable declaration styles are used. In particular, I am confused about when I should put square brackets after the variable type and when I should put them after the variable name. For example, given int<lower = 0> L; // length of my data, let's consider:
real N[L]; // my variable
versus
vector[L] N; // my variable
From what I understand, both declare a variable N as a vector of length L.
Is the only difference between the two that the first way specifies the variable type? Can they be used interchangeably? Should they belong do different parts of the Stan code (e.g., data vs parameters or model)?
Thanks for explaining!
real name[size] and vector[size] name can be used pretty interchangeably. They are stored differently internally, so you can get better performance with one or the other. Some operations might also be restricted to one and the other (e.g. vector multiplication) and the optimal order to loop over them changes. E.g. with a matrix vs. a 2-D array, it is more efficient to loop over rows first vs. columns first, but those will come up if you have a more specific example. The way to read this is:
real name[size];
means name is an array of type real, so a bunch of reals that are stored together.
vector[size] name;
means that name is a vector of size size, which is also a bunch of reals stored together. But the vector data type in STAN is based on the eigen c++ library (c++) and that allows for other operations.
You can also create arrays of vectors like this:
vector[N] name[K];
which is going to produce an array of K vectors of size N.
Bottom line: You can get any model running with using vector or real, but they're not necessarily equivalent in the computational efficiency.
So I have an external C function that returns a pointer to an array. I'm trying to figure out how to convert the pointer to something that can be be displayed on the screen using the latest version of LabView (2019, assume I have all the toolkits).
The C function signature imports fine and is designed to display 16 bit images.
STATUS DemoImage(unsigned short** ptr, int64* rows, int64* columns, int64 image_idx)
with ptr eventually filling a pointer containing the memory location to 16 bit image. rows, columns work as expected.
Whats the name of the controllers that convert the data type to something that can be displayed? I'd also appreciate answers that only address how to display a 8 bit images as I can convert them in my own library if worst, comes to worst.
There is a vi.lib VI not on the palette that you can use: GetValueByPointer.
Detailed walkthrough
For the step-by-step explanation, see this NI document.
2D arrays are represented as an array of arrays. Since an array is really a pointer, a 2D array is a pointer to an array of pointers, where each pointer points to the individual rows of the array. So in order to dereference a 2D Array, you must first dereference the individual pointers to each row, and then dereference in individual elements in each row. The following snippet shows an example of this:
Download examples
For a download with examples, see this one instead, section 4.d.
Returning values by reference (pass by ref)
Function:void ReturningValuesByReference_2DArrayOfIntegers (int rows, int cols, int ***newArray);
VI:Returning Values By Reference 2D Array Of Integers Complete.vi
I'm trying to create a Minesweeper game.
I have a 4x4 set of buttons equally spaced in main.Storyboard.
My plan is to create a random array which places a 0 or * in the 1st/2nd/3rd/4th arrays. I would do this by using the arc4Random method.
With the remaining blank cells, I then have to check how many mines there could be for the 8 (potential) squares around the cell/button. This would be governed by the boundary conditions (0,0 to 3,3).
Once this is set up, I would then set the background and number label to the same colour. I could then write an if or else statement to change the colour after each button is pressed.
I'm quite struggling how to start this off and actually write this. Can anyone please give me some advice please?
Well,
you can get a boolean like this.
bool hasMine = arc4random() % 2;
this will give you 50% chance to get a bomb... if you want less bomb, increase the value (3 will give you 2 bomb free square, for one with a bomb, etc..)
then a "" or a "*" like this;
NSSString * value = hasMine ? #"*" : #"" ;
then it's just a matter of a for loop to populate your arrays.
for the sake of performance, I wouldn't use a n x n nested array but a single arrray of nxn size (in your case a array with 16 value). Then I will set a tag for 0 to (nxn -1) to each button based on its position, and on click I'll get the tag of the pressed button and retrive the value of the object at this position in the array
There must be some 'pythonic' way to do this, but I don't think np.place, np.insert, or np.put are what I'm looking for. I want to replace the values inside of a large 3D array A with those of a smaller 3D array B, starting at location [i,j,k] in the larger array. See drawing:
I want to type something like A[i+, j+, k+] = B, or np.embed(B, A, (i,j,k)) but of course those are not right.
EDIT: Oh, there is this. So I should modify the question to ask if this is the best way (where "best" means fastest for a 500x500x50 array of floats on a laptop):
s0, s1, s2 = B.shape
A[i:i+s0, j:j+s1, k:k+s2] = B
Your edited answer looks fine for the 3D case.
If you want the "embed" function you mentioned in the original post, for arrays of any number of dimensions, the following should work:
def embed( small_array, big_array, big_index):
"""Overwrites values in big_array starting at big_index with those in small_array"""
slices = [np.s_[i:i+j] for i,j in zip(big_index, small_array.shape)]
big_array[slices]=small_array
It may be worth noting that it's not obvious how one would want "embed" to perform in cases where big_array has more dimensions than small_array does. E.g., I could imagine someone wanting a 1:1 mapping from small_array members to overwritten members of big_array (equivalent to adding extra length-1 dimensions to small_array to bring its ndim up to that of big_array), or I could imagine someone wanting small_array to broadcast out to fill the remainder of big_array for the "missing" dimensions of small_array. Anyway, you might want to avoid calling the function in those cases, or to tweak the function to ensure it will do what you want in those cases.
I am writing a game, which need a map, and I want to store the map. The first thing I can think of, is using a 2D-array. But the problem is what data should I store in the 2D-array. The player can tap different place to have different reaction. So, I am thinking store a 2D-array with objects, when player click some position, and I find it in the array, and use the object in that array to execute a cmd. But I have a concern that storing lots of object may use lots of memory. So, I am think storing char/int only. But it seems that not enough for me. I want to store the data like that:
{
Type:1
Color:Green
}
No matter what color is, if they are all type 1, the have same reactions in logic, but the visual effect is based on the color. So, it is not easy to store using a prue char/int data, unless I make something like this:
1-5 --> all type 1. 1=color green ,
2=color red, 3 = color yellow.... ...
6-10 --> all type 2. 2 = color green,
2 = color red ... ...
So, do you have any ideas on how to minimize the ram use, but also easy for me to read... ...thx
Go ahead and store a bunch of objects in the array, but with these two refinements:
Store a pointer to the object, not the object itself. (Objective C may handle this for you automatically; I don't know.)
Remember that a pointer to a single object can appear in more than one position in the array. All squares that share the same color and behavior can share an object.
It would also help if you did the math on the size of the array and the number of distinct squares so we can know exactly how much RAM you are talking about.