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plyr

plyr is a set of tools for a common set of problems: you need to split up a big data structure into homogeneous pieces, apply a function to each piece and then combine all the results back together. For example, you might want to:

fit the same model each patient subsets of a data frame
quickly calculate summary statistics for each group
perform group-wise transformations like scaling or standardising

It's already possible to do this with base R functions (like split and the apply family of functions), but plyr makes it all a bit easier with:

totally consistent names, arguments and outputs
convenient parallelisation through the foreach package
input from and output to data.frames, matrices and lists
progress bars to keep track of long running operations
built-in error recovery, and informative error messages
labels that are maintained across all transformations

Considerable effort has been put into making plyr fast and memory efficient, and in many cases plyr is as fast as, or faster than, the built-in equivalents.

A detailed introduction to plyr has been published in JSS: "The Split-Apply-Combine Strategy for Data Analysis", http://www.jstatsoft.org/v40/i01/. You can find out more at http://had.co.nz/plyr/, or track development at http://github.com/hadley/plyr. You can ask questions about plyr (and data manipulation in general) on the plyr mailing list. Sign up at http://groups.google.com/group/manipulatr.

Status

plyr is retired: this means only changes necessary to keep it on CRAN will be made. We recommend using dplyr (for data frames) or purrr (for lists) instead.

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Install

install.packages('plyr')

Monthly Downloads

358,508

Version

1.8.5

License

MIT + file LICENSE

Issues

Pull Requests

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Repository

https://github.com/hadley/plyr

Homepage

http://had.co.nz/plyr

Maintainer

Hadley Wickham

Last Published

December 10th, 2019

Functions in plyr (1.8.5)

Split data frame, apply function, and return results in an array.

Dimension names.

Split data frame, apply function, and discard results.

create_progress_bar

Create progress bar.

Evaluate a quoted list of variables.

Column-wise function.

Numeric id for a vector.

Compute a unique numeric id for each unique row in a data frame.

Yearly batting records for all major league baseball players

Split data frame, apply function, and return results in a data frame.

Descending order.

Aggregate multiple functions into a single function.

Check if a data frame is empty.

Capture current evaluation context.

Count the number of occurences.

Join two data frames together.

Fail with specified value.

Number of dimensions.

Construct an immutable data frame.

An indexed data frame.

An indexed array.

Split list, apply function, and return results in a list.

list_to_dataframe

List to data frame.

Recursively join a list of data frames.

Determine if a vector is discrete.

Split data frame, apply function, and return results in a list.

Is a formula? Checks if argument is a formula

Split list, apply function, and discard results.

Modify names by name, not position.

Replace specified values with new values, in a vector or factor.

Replace specified values with new values, in a factor or character vector.

Graphical progress bar, powered by Tk.

Generate labels for split data frame.

Extract matching rows of a data frame.

List to vector.

Graphical progress bar, powered by Windows.

Experimental iterator based version of llply.

Split an array by .margins.

Mutate a data frame by adding new or replacing existing columns.

Monthly ozone measurements over Central America.

plyr-deprecated

Deprecated Functions in Package plyr

Call function with arguments in array or data frame, returning a list.

Split iterator that returns values, not indices.

Call function with arguments in array or data frame, discarding results.

Call function with arguments in array or data frame, returning an array.

Text progress bar.

Call function with arguments in array or data frame, returning a data frame.

Join keys. Given two data frames, create a unique key for each row.

Vector aggregate.

Text progress bar with time.

Toggle row names between explicit and implicit.

Replicate expression and discard results.

Apply with built in try. Uses compact, lapply and tryNULL

plyr: the split-apply-combine paradigm for R.

Take a subset along an arbitrary dimension

Summarise a data frame.

Print quoted variables.

Round to multiple of any number.

Split list, apply function, and return results in an array.

Replicate expression and return results in a list.

Replicate expression and return results in a array.

Split list, apply function, and return results in a data frame.

Number of unique values.

Quote variables to create a list of unevaluated expressions for later evaluation.

Quick data frame.

Compute names of quoted variables.

`Splat' arguments to a function.

rbind.fill.matrix

Bind matrices by row, and fill missing columns with NA.

Combine data.frames by row, filling in missing columns.

Split a data frame by variables.

Replicate expression and return results in a data frame.

Null progress bar

Reduce dimensions.

Function that always returns true.

Remove splitting variables from a data frame.

Try, with default in case of error.

Split array, apply function, and discard results.

Convert split list to regular list.

Split array, apply function, and return results in a data frame.

Order a data frame by its colums.

Split array, apply function, and return results in a list.

Convert input to quoted variables.

as.data.frame.function

Make a function return a data frame.

Split array, apply function, and return results in an array.