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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 https://had.co.nz/plyr/, or track development at https://github.com/hadley/plyr. You can ask questions about plyr (and data manipulation in general) on the plyr mailing list. Sign up at https://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

385,900

Version

1.8.7

License

MIT + file LICENSE

Issues

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Repository

https://github.com/hadley/plyr

Homepage

http://had.co.nz/plyr

Maintainer

Last Published

March 24th, 2022

Functions in plyr (1.8.7)

Split array, apply function, and discard results.

Convert input to quoted variables.

Dimension names.

Order a data frame by its colums.

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

Convert split list to regular list.

as.data.frame.function

Make a function return a data frame.

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

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

Yearly batting records for all major league baseball players

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

Column-wise function.

Descending order.

Capture current evaluation context.

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

Number of dimensions.

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

Split data frame, apply function, and discard results.

Numeric id for a vector.

create_progress_bar

Create progress bar.

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

Aggregate multiple functions into a single function.

Split iterator that returns values, not indices.

Check if a data frame is empty.

Evaluate a quoted list of variables.

Count the number of occurences.

Is a formula? Checks if argument is a formula

Fail with specified value.

An indexed data frame.

Determine if a vector is discrete.

Recursively join a list of data frames.

Split list, apply function, and discard results.

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

An indexed array.

Construct an immutable data frame.

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

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

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

List to vector.

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

list_to_dataframe

List to data frame.

Join two data frames together.

Monthly ozone measurements over Central America.

plyr-deprecated

Deprecated Functions in Package plyr

Experimental iterator based version of llply.

Compute names of quoted variables.

Number of unique values.

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

Quick data frame.

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

Extract matching rows of a data frame.

Reduce dimensions.

Replicate expression and return results in a data frame.

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

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

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

`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.

Remove splitting variables from a data frame.

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

Print quoted variables.

Split a data frame by variables.

Text progress bar.

Toggle row names between explicit and implicit.

Summarise a data frame.

Text progress bar with time.

Vector aggregate.

Replicate expression and return results in a list.

Round to multiple of any number.

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

Null progress bar

Take a subset along an arbitrary dimension

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

Modify names by name, not position.

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

Graphical progress bar, powered by Tk.

Generate labels for split data frame.

Split an array by .margins.

Graphical progress bar, powered by Windows.

Replicate expression and discard results.

Replicate expression and return results in a array.

Function that always returns true.

Try, with default in case of error.