Manipulating Data

General

• Sorting
• Randomizing order
• Converting between vector types - Numeric vectors, Character vectors, and Factors
• Finding and removing duplicate records
• Comparing vectors or factors with NA
• Recoding data
• Mapping vector values - Change all instances of value x to value y in a vector

Factors

• Renaming levels of a factor
• Re-computing the levels of factor
• Changing the order of levels of a factor

Data Frames

• Renaming columns in a data frame
• Adding and removing columns from a data frame
• Reordering the columns in a data frame
• Merging data frames
• Comparing data frames - Search for duplicate or unique rows across multiple data frames.
• Re-computing the levels of all factor columns in a data frame

Restructuring data

• Converting data between wide and long format
• Summarizing data - Collapse a data frame on one or more variables to find mean, count, standard deviation, standard error of the mean, and confidence intervals
• Converting between data frames and contingency tables - Data frames with individual cases, data frames with counts, and contingency tables

Sequential data

• Calculating a moving average
• Averaging a sequence in blocks - Convert a sequence into blocks of a given length and average within each block.
• Finding sequences of identical values
• Filling in NAs with last non-NA value