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Spatial Interpolation

In this repository, the inverse distance weighting algorithm is used concurrently with the Spark Framework.
There are 3 branches in this repository: Spark RDD, Spark Dataframe and Spark SQL.

The algorithm

The Inverse Distance Weighting (IDW) algorithm is a type of interpolation method used to estimate unknown values based on known values at surrounding points. The key idea is that points closer to the location of interest have a greater influence on the estimated value than points further away. The influence of each known point is inversely proportional to its distance from the location of interest, typically raised to a power (often 2, but it can vary). This method is commonly used in geographic information systems (GIS) for spatial interpolation.

Where:

  • ( Z(x) ) is the estimated value (in this case, temperature) at the location ( x ).
  • ( N ) is the number of known points.
  • ( Z(x_i) ) is the value (in this case, temperature) at the known point ( x_i ).
  • ( d(x, x_i) ) is the distance between the location ( x ) and the known point ( x_i ).
  • ( p ) is the power parameter that controls the rate of distance decay (commonly set to 2, but in this repository is set to 3).

Application

Let's pretend the following situation: you know the temperature of N points, but you don't know the temperature of a specific point. Based on the temperature of the N points that you already know, you can predict the temperature of the mentioned specific point.