Home PHP C# C++ Android Java Javascript Python IOS SQL HTML Categories

Algorithm to find adjacent cells in a matrix

Yes. If you really need to find the neighbors, then you have an option to use graphs.

Graphs are basically vertex classes w/ their adjacent vertexes, forming an edge. We can see here that 2 forms an edge w/ 5, and 1 form an edge w/ 5, etc.

If you're going to need to know the neighbors VERY frequently(because this is inefficient if you're not), then implement your own vertex class, wrapping the value(5) in a generic T val variable. Have a hashtable of adjacent numbers and their respective distances(1 in this case, and if you need to find neighbors of 2, then you're going to need to assign those as well) by add(vertex, distance) into the hashtable.

Later on, simply iterate through the hashtable for the neighbors.

However, for an array this simple, there isn't much overhead for just doing a for loop and using "a bunch of if statements". In reality you only need to have if(boundaries check) for every direction(which is 4).

Hopefully this helps.

Categories : Algorithm

Related to : Algorithm to find adjacent cells in a matrix
Add cells values based on key word in adjacent cell string - kind of sumif?
In cell P1, paste the following formula: =IF(ISNUMBER(SEARCH("rev",B1)),A1,) Use the mouse to extend the formula to the right to cell Y1. The formula does a case-insensitive search of the cell to see if it contains "rev". This will capture "Revenue", "revenue", and "rev". If there's a match, then it copies the cell to the left. Otherwise it enters 0. Now, in cell Z1, simply sum cells P1 th

Categories : Excel
Fastest algorithm for computing the determinant of a matrix?
I believe the fastest in practice (and commonly used) algorithm is the Strassen Algorithm. You can find explanation on wiki ( along with sample C code. Algorithms based on Coppersmith-Winograd's multiplication algorithms ( are too complex to be practical, though they have best asymp

Categories : Algorithm
How to compute distances between centroids and data matrix (for kmeans algorithm)
Your main question seems to be how to calculate distances between a data matrix and some set of points ("centers"). For this you can write a function that takes as input a data matrix and your set of points and returns distances for each row (point) in the data matrix to all the "centers". Here is such a function: myEuclid <- function(points1, points2) { distanceMatrix <- matrix(NA, n

Categories : R
Eigen sparse matrix multiplications seem to compute full matrix
Basically, the document is sightly confusing for me at least. the way to do it is simply: SpMat mat_3 = mat_1 * mat_2 No dense matrix is created along the way. Eigen rocks!

Categories : C++
python - how to compute correlation-matrix with nans in data-matrix
You can convert all nan values to zeros using np.nan_to_num() and then proceed further. Demo: >>> data array([[ 5.1, 3.5, 1.4, 0.2], [ 4.9, 3. , nan, 0.2], [ 4.7, 3.2, 1.3, nan], [ nan, 3.1, 1.5, 0.2]]) >>> np.cov(data.T) array([[ nan, nan, nan, nan], [ nan, 0.04666667, nan, nan],

Categories : Python
Recently Add
Proving optimality for a new algorithm that finds minimum spanning tree
why this assembly piece of code do jmp forever
Find out if segment is fully inside of polygon
Algorithm for coloring a hexagon tile map with minimum distance (3) for reoccurring colors
Sort pairs to be more consecutive
To find three unique numbers whose number of occurrence is even
Dealing with duplication between unit and integration tests
reflection and symmetry in back tracking queens
Big O analysis for method with multiple parameters
Divide Huge Array of Numbers in Buckets
Algorithm to find adjacent cells in a matrix
Why this code gives WA for Petersen Graph(codechef)?
Complexity of this prime number search algorithm
How to detect if a file has changed?
Given string x,y and z. Determine if z is a shuffle
Basic decryption for simple encryption algorithm
An efficient way to assign user_ids to huge dataset under certain conditions
What's a more efficient implementation of this puzzle?
Generating prime numbers in poly-time
What if I do not use G transpose in calculating Strongly Connected Components?
Dividing an array into optimum no of equal sum sublists
Counting derangements
How to iterate through all cases when partitioning objects
Algorithm: How to find closest element, having coordinates and dimension
Developing player rankings with ELO
How to transform two set of discrete points ( vectors ) to help plotting them on a common scale
Heap Sort Space Complexity
complex root finding algorithm
Every possible combination algorithm
RSA Cryptosystem - Retrieve m
© Copyright 2017 Publishing Limited. All rights reserved.