These presentations describe how to manipulate and subset R data objects using indexing. The slides for this material can be found here.
Indexing Vectors to Manipulate Data in R
How to index vectors by position, logical expression and name. Using conditional expressions and logical indexes to identify and select one vector against another. Using logical indexing to categorize a variable into mutually exclusive groups.
Indexing Matrices and Arrays in R
How to index matrices and arrays by position, name and logical expression.
Indexing Lists in R
How to index lists by position using the double bracket notation, by logical expression, and by name. Using indexing to extract results from functions that return lists.
Indexing and Manipulating Data Frames in R
How to index data frame observations (rows) and variables (columns) by position, name and logical expressions to manipulate and recode or replace data elements.
Subsetting Data Frames in R
Subsetting a data frame using indexing and logical expressions to restrict rows and variables. Introduction to the base R function subset() as an alternative to indexing.