Code – Page 2 – Coding Musings

Finding an Exit from a Maze

On January 26, 2018

Finding an Exit from a Maze using undirected graphs.

We can think of a maze as a rectangular grid of cells with paths between adjacent cells. If we want to find if there is a path from a given cell to a given exit from the maze, where the exit is represented by a cell, you can represent the maze as an undirected graph.

The nodes of the graph are cells of the maze, and two nodes are connected an undirected edge if they are adjacent and there is no wall between them. Therefore we can surmise we just need to see if a path, series of edges connecting the nodes, to determine if the two nodes are connected.

See code below.

Spark – Streaming Data

By Michael_M

On January 22, 2018

In Python, code, Spark

Spark – Streaming Data, Capturing and Querying

Today we will look at how to capture streaming data and perform some simple queries as the data is streamed. We will use the regular expressions library and the PySpak library. The streaming data comes from a weather station that transmits different weather at different intervals. We will need to find the correct data out of the stream and output the results.

Let’s get started.

Spark – SQLContext

By Michael_M

On January 21, 2018

In Python, code, Spark

Spark – SQLContext

Today we will look at the SQLContext object from the PySpark library and how you can use it to connect to a local database. In the example below we will:
Connect to a local PostgreSQL database and read the contents into a dataframe.
Run some simple SQL queries
And join two data frames together

Let’s get started.

Hadoop Spark – Hello World, Word Count

By Michael_M

On January 18, 2018

In Python, code, Spark

Hadoop Spark – Word Count

One of the first things to do in most programming languages is create a “Hello World!” program. The equivalent in Spark is to create a program that will read the contents of a file and count the number of occurrences of each word.

Below I will show a basic example, so let’s start counting.

Read CSV files using Python Panda Dataframes

By Michael_M

On January 12, 2018

In Python Pandas, Python, code

The great thing about the Panda’s library for Python is how easily it can manipulate data sources. We will look at one of the first things you will want to do, read a .csv file.

Class for Parsing NGrams

By Michael_M

On December 6, 2017

In code, R, SQL

Train an NGram Model

Will take the ngrams, reading and writing from the SQLite database and train the model utilizing Katz-Backoff methodology on the likelihood of the next word.

See code below

File Handler for RDS Formatted Files

By Michael_M

On December 5, 2017

In code, R

File Handler for RDS Formatted Files

Using a list, load RDS formatted files into standard data frame. Allows for grouping multiple files into one data frame for processing.

See code below

SQLite Interface Class for R

By Michael_M

On December 4, 2017

In code, R, SQL

SQLite Interface Class for R

I wrote an interface class to help with working with the SQLite database.

Methods include, selectQuery, updateQuery, readTable, writeTable

see code below

Binary Search Tree – Is BST?

By Michael_M

On November 22, 2017

In Python, code

Binary Search Tree

Traverse the tree in natural order and test if each node is between the previous and the next node. Properly detect duplicate values. If a wrong sub-tree is encountered immediately stop the script and indicate the error.

See code below