R Syntax for a Simple For Loop

For loops in R are useful tidbits of code to keep track of a counter, iterate through a variable, or do a complex operation on a subset of variables.  Below is an example R script showing the code and syntax needed to do some simple tasks with R for loops.

Import Variable into R Script

I always forget the syntax for defining a variable to read into an R script. It is relatively easy to import an external variable into R (such as a Unix variable or user-defined variable). The option to feed R a variable is incredibly useful on a cluster system where you want to farm out a large job into smaller sized pieces. Here is example code for doing so:

Quick Primer on Python Shelve

Python shelve is a convenient means of storing a Python data object to disk for later use. The feature behaves similarly to a Python dictionary object and uses a lot of the same syntax.  Each object that is shelved has a key which is associated with the object so it can be quickly and efficiently accessed from disk. A shelved object must be something that can be pickled with the pickle package, essentially making shelves an easy way to organize and store pickled objects. "Pickling" is the process of making a Python object into a byte stream, and the inverse, "unpickling" is where the byte stream is restored back into the original Python object. Pickling is synonymous with serialization, marshalling, and flattening of data. Example Python objects that can be pickled include: integers, lists, tupules, sets, dictionaries, and classes. In addition to saving items to disk, shelves allow for quick access to portions of large data objects and can store them in binary format by specifying a protocol greater than 0.  Here are some simple Python scripts that hopefully serve as a useful tutorial to learn about shelves and their syntax.  The example focuses on saving dictionaries into a shelve, but it can be easily extended into other objects as well.

Syntax for a User-Defined R Function

R functions are incredibly handy ways to have R carry out repetitive tasks for you without having to copy and paste lines in your code over and over again.  Since I don't daily write new R functions, I sometimes forget what the syntax is to create these custom functions.  Here's an example function I made to tell if a number is even or odd:


To run a custom R function simply use the function name with all the needed input variable in parenthesis (ex: even_num(413)).