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Extract.factor: Extract or Replace Parts of a Factor

Extract.factor

R Documentation

Extract or Replace Parts of a Factor

Description

Extract or replace subsets of factors.

Usage

## S3 method for class 'factor'x[..., drop = FALSE]## S3 method for class 'factor'x[[...]]## S3 replacement method for class 'factor'x[...] <- value## S3 replacement method for class 'factor'x[[...]] <- value

Arguments

`x`	a factor
`...`	a specification of indices – see`Extract`.
`drop`	logical. If true, unused levels are dropped.
`value`	character: a set of levels. Factor values are coerced tocharacter.

Details

When unused levels are dropped the ordering of the remaining levels ispreserved.

Ifvalue is not inlevels(x), a missing value isassigned with a warning.

Anycontrasts assigned to the factor are preservedunlessdrop = TRUE.

The[[ method supports argumentexact.

Value

A factor with the same set of levels asx unlessdrop = TRUE.

See Also

factor,Extract.

Examples

## following example(factor)(ff <- factor(substring("statistics", 1:10, 1:10), levels = letters))ff[, drop = TRUE]factor(letters[7:10])[2:3, drop = TRUE]

abbreviate: Abbreviate Strings agrep: Approximate String Matching (Fuzzy Matching)all: Are All Values True?all.equal: Test if Two Objects are (Nearly) Equal allnames: Find All Names in an Expression any: Are Some Values True?aperm: Array Transposition append: Vector Merging apply: Apply Functions Over Array Margins args: Argument List of a Function Arithmetic: Arithmetic Operators array: Multi-way Arrays as.data.frame: Coerce to a Data Frame as.Date: Date Conversion Functions to and from Character as.environment: Coerce to an Environment Object as.function: Convert Object to Function AsIs: Inhibit Interpretation/Conversion of Objects asplit: Split Array/Matrix By Its Margins as.POSIXlt: Date-time Conversion Functions assign: Assign a Value to a Name assignOps: Assignment Operators attach: Attach Set of R Objects to Search Path attr: Object Attributes attributes: Object Attribute Lists autoload: On-demand Loading of Packages backsolve: Solve an Upper or Lower Triangular System base-defunct: Defunct Functions in Package 'base'base-deprecated: Deprecated Functions in Package 'base'base-internal: Internal Objects in Package 'base'basename: Manipulate File Paths base-package: The R Base Package Bessel: Bessel Functions bincode: Bin a Numeric Vector bindenv: Binding and Environment Locking, Active Bindings bitwise: Bitwise Logical Operations body: Access to and Manipulation of the Body of a Function bquote: Partial substitution in expressions browser: Environment Browser browserText: Functions to Retrieve Values Supplied by Calls to the Browser builtins: Returns the Names of All Built-in Objects by: Apply a Function to a Data Frame Split by Factors c: Combine Values into a Vector or List call: Function Calls callCC: Call With Current Continuation CallExternal: Modern Interfaces to C/C++ code capabilities: Report Capabilities of this Build of R cat: Concatenate and Print cbind: Combine R Objects by Rows or Columns character: Character Vectors char.expand: Expand a String with Respect to a Target Table charmatch: Partial String Matching chartr: Character Translation and Casefolding chkDots: Warn About Extraneous Arguments in the "..." of Its Caller chol: The Choleski Decomposition chol2inv: Inverse from Choleski (or QR) Decomposition class: Object Classes col: Column Indexes colnames: Row and Column Names Colon: Colon Operator colSums: Form Row and Column Sums and Means commandArgs: Extract Command Line Arguments comment: Query or Set a '"comment"' Attribute Comparison: Relational Operators complex: Complex Numbers and Basic Functionality conditions: Condition Handling and Recovery conflicts: Search for Masked Objects on the Search Path connections: Functions to Manipulate Connections (Files, URLs, ...)Constants: Built-in Constants contributors: R Project Contributors Control: Control Flow copyright: Copyrights of Files Used to Build R crossprod: Matrix Crossproduct Cstack_info: Report Information on C Stack Size and Usage cumsum: Cumulative Sums, Products, and Extremes curlGetHeaders: Retrieve Headers from URLs cut: Convert Numeric to Factor cut.POSIXt: Convert a Date or Date-Time Object to a Factor data.class: Object Classes data.frame: Data Frames dataframeHelpers: Data Frame Auxiliary Functions data.matrix: Convert a Data Frame to a Numeric Matrix date: System Date and Time Dates: Date Class DateTimeClasses: Date-Time Classes dcf: Read and Write Data in DCF Format debug: Debug a Function Defunct: Marking Objects as Defunct delayedAssign: Delay Evaluation deparse: Expression Deparsing deparseOpts: Options for Expression Deparsing Deprecated: Marking Objects as Deprecated det: Calculate the Determinant of a Matrix detach: Detach Objects from the Search Path dev: Lists of Open/Active Graphics Devices diag: Matrix Diagonals diff: Lagged Differences difftime: Time Intervals / Differences dim: Dimensions of an Object dimnames: Dimnames of an Object do.call: Execute a Function Call dontCheck: Identity Function to Suppress Checking dots: ..., '..1', etc used in Functions double: Double-Precision Vectors dput: Write an Object to a File or Recreate it drop: Drop Redundant Extent Information droplevels: Drop Unused Levels from Factors dump: Text Representations of R Objects duplicated: Determine Duplicate Elements dynload: Foreign Function Interface eapply: Apply a Function Over Values in an Environment eigen: Spectral Decomposition of a Matrix encodeString: Encode Character Vector as for Printing Encoding: Read or Set the Declared Encodings for a Character Vector environment: Environment Access EnvVar: Environment Variables eval: Evaluate an (Unevaluated) Expression exists: Is an Object Defined?expand.grid: Create a Data Frame from All Combinations of Factor Variables expression: Unevaluated Expressions Extract: Extract or Replace Parts of an Object Extract.data.frame: Extract or Replace Parts of a Data Frame Extract.factor: Extract or Replace Parts of a Factor Extremes: Maxima and Minima extSoftVersion: Report Versions of Third-Party Software factor: Factors file.access: Ascertain File Accessibility file.choose: Choose a File Interactively file.info: Extract File Information file.path: Construct Path to File files: File Manipulation files2: Manipulation of Directories and File Permissions file.show: Display One or More Text Files findInterval: Find Interval Numbers or Indices find.package: Find Packages force: Force Evaluation of an Argument forceAndCall: Call a function with Some Arguments Forced Foreign: Foreign Function Interface Foreign-internal: Internal Versions of the Foreign Function Interface formals: Access to and Manipulation of the Formal Arguments format: Encode in a Common Format formatc: Formatting Using C-style Formats formatDL: Format Description Lists format.info: format(.) Information format.pval: Format P Values function: Function Definition funprog: Common Higher-Order Functions in Functional Programming...gc: Garbage Collection gc.time: Report Time Spent in Garbage Collection gctorture: Torture Garbage Collector get: Return the Value of a Named Object getCallingDLL: Compute DLL for Native Interface Call getDLLRegisteredRoutines: Reflectance Information for C/Fortran routines in a DLL getLoadedDLLs: Get DLLs Loaded in Current Session getNativeSymbolInfo: Obtain a Description of one or more Native (C/Fortran)...gettext: Translate Text Messages getwd: Get or Set Working Directory gl: Generate Factor Levels grep: Pattern Matching and Replacement grepRaw: Pattern Matching for Raw Vectors groupGeneric: S3 Group Generic Functions grouping: Grouping Permutation gzcon: (De)compress I/O Through Connections hexmode: Display Numbers in Hexadecimal Hyperbolic: Hyperbolic Functions iconv: Convert Character Vector between Encodings icuSetCollate: Setup Collation by ICU identical: Test Objects for Exact Equality identity: Identity Function ifelse: Conditional Element Selection integer: Integer Vectors interaction: Compute Factor Interactions interactive: Is R Running Interactively?Internal: Call an Internal Function InternalMethods: Internal Generic Functions invisible: Change the Print Mode to Invisible is.finite: Finite, Infinite and NaN Numbers is.function: Is an Object of Type (Primitive) Function?is.language: Is an Object a Language Object?is.object: Is an Object 'internally classed'?ISOdatetime: Date-time Conversion Functions from Numeric Representations isR: Are we using R, rather than S?is.recursive: Is an Object Atomic or Recursive?isS4: Test for an S4 object is.single: Is an Object of Single Precision Type?isSymmetric: Test if a Matrix or other Object is Symmetric (Hermitian)is.unsorted: Test if an Object is Not Sorted jitter: 'Jitter' (Add Noise) to Numbers kappa: Compute or Estimate the Condition Number of a Matrix kronecker: Kronecker Products on Arrays l10n_info: Localization Information labels: Find Labels from Object La_library: LAPACK Library lapply: Apply a Function over a List or Vector Last.value: Value of Last Evaluated Expression La_version: LAPACK Version lazyload: Lazy Load a Database of R Objects length: Length of an Object lengths: Lengths of List or Vector Elements levels: Levels Attributes libcurlVersion: Report Version of libcurl libPaths: Search Paths for Packages library: Loading/Attaching and Listing of Packages library.dynam: Loading DLLs from Packages license: The R License Terms list: Lists - Generic and Dotted Pairs list2DF: Create Data Frame From List list2env: From A List, Build or Add To an Environment list.files: List the Files in a Directory/Folder load: Reload Saved Datasets locales: Query or Set Aspects of the Locale Log: Logarithms and Exponentials Logic: Logical Operators logical: Logical Vectors LongVectors: Long Vectors lower.tri: Lower and Upper Triangular Part of a Matrix ls: List Objects make.names: Make Syntactically Valid Names make.unique: Make Character Strings Unique mapply: Apply a Function to Multiple List or Vector Arguments marginSums: Compute table margins match: Value Matching match.arg: Argument Verification Using Partial Matching match.call: Argument Matching match.fun: Extract a Function Specified by Name MathFun: Miscellaneous Mathematical Functions matmult: Matrix Multiplication mat.or.vec: Create a Matrix or a Vector matrix: Matrices maxCol: Find Maximum Position in Matrix mean: Arithmetic Mean memCompress: In-memory Compression and Decompression memlimits: Query and Set Heap Size Limits Memory: Memory Available for Data Storage Memory-limits: Memory Limits in R memory.profile: Profile the Usage of Cons Cells merge: Merge Two Data Frames message: Diagnostic Messages missing: Does a Formal Argument have a Value?mode: The (Storage) Mode of an Object NA: 'Not Available' / Missing Values name: Names and Symbols names: The Names of an Object nargs: The Number of Arguments to a Function nchar: Count the Number of Characters (or Bytes or Width)nlevels: The Number of Levels of a Factor noquote: Class for 'no quote' Printing of Character Strings norm: Compute the Norm of a Matrix normalizePath: Express File Paths in Canonical Form notyet: Not Yet Implemented Functions and Unused Arguments nrow: The Number of Rows/Columns of an Array ns-dblcolon: Double Colon and Triple Colon Operators ns-hooks: Hooks for Namespace Events ns-internal: Namespace Internals ns-load: Loading and Unloading Name Spaces ns-reflect: Namespace Reflection Support ns-topenv: Top Level Environment NULL: The Null Object numeric: Numeric Vectors NumericConstants: Numeric Constants numeric_version: Numeric Versions octmode: Display Numbers in Octal on.exit: Function Exit Code Ops.Date: Operators on the Date Class options: Options Settings order: Ordering Permutation outer: Outer Product of Arrays Paren: Parentheses and Braces parse: Parse R Expressions paste: Concatenate Strings path.expand: Expand File Paths pcre_config: Report Configuration Options for PCRE pipeOp: Forward Pipe Operator Platform: Platform Specific Variables plot: Generic X-Y Plotting pmatch: Partial String Matching polyroot: Find Zeros of a Real or Complex Polynomial pos.to.env: Convert Positions in the Search Path to Environments pretty: Pretty Breakpoints Primitive: Look Up a Primitive Function print: Print Values print.dataframe: Printing Data Frames print.default: Default Printing prmatrix: Print Matrices, Old-style proc.time: Running Time of R prod: Product of Vector Elements proportions: Express Table Entries as Fraction of Marginal Table pushBack: Push Text Back on to a Connection qr: The QR Decomposition of a Matrix qraux: Reconstruct the Q, R, or X Matrices from a QR Object quit: Terminate an R Session Quotes: Quotes Random: Random Number Generation Random-user: User-supplied Random Number Generation range: Range of Values rank: Sample Ranks rapply: Recursively Apply a Function to a List raw: Raw Vectors rawConnection: Raw Connections rawConversion: Convert to or from (Bit/Packed) Raw Vectors RdUtils: Utilities for Processing Rd Files readBin: Transfer Binary Data To and From Connections readChar: Transfer Character Strings To and From Connections readline: Read a Line from the Terminal readLines: Read Text Lines from a Connection readRDS: Serialization Interface for Single Objects readRenviron: Set Environment Variables from a File Recall: Recursive Calling regex: Regular Expressions as used in R reg.finalizer: Finalization of Objects regmatches: Extract or Replace Matched Substrings rep: Replicate Elements of Vectors and Lists replace: Replace Values in a Vector Reserved: Reserved Words in R rev: Reverse Elements Rhome: Return the R Home Directory rle: Run Length Encoding rm: Remove Objects from a Specified Environment Round: Rounding of Numbers round.POSIXt: Round / Truncate Data-Time Objects row: Row Indexes row.names: Get and Set Row Names for Data Frames rowsum: Give Column Sums of a Matrix or Data Frame, Based on a...S3method: Register S3 Methods sample: Random Samples and Permutations save: Save R Objects scale: Scaling and Centering of Matrix-like Objects scan: Read Data Values search: Give Search Path for R Objects seek: Functions to Reposition Connections seq: Sequence Generation seq.Date: Generate Regular Sequences of Dates seq.POSIXt: Generate Regular Sequences of Times sequence: Create A Vector of Sequences serialize: Simple Serialization Interface sets: Set Operations setTimeLimit: Set CPU and/or Elapsed Time Limits showConnections: Display Connections shQuote: Quote Strings for Use in OS Shells sign: Sign Function sink: Send R Output to a File slice.index: Slice Indexes in an Array slotOp: Extract or Replace A Slot socketSelect: Wait on Socket Connections solve: Solve a System of Equations sort: Sorting or Ordering Vectors source: Read R Code from a File, a Connection or Expressions Special: Special Functions of Mathematics split: Divide into Groups and Reassemble sprintf: Use C-style String Formatting Commands sQuote: Quote Text srcfile: References to Source Files and Code standardGeneric: Formal Method System - Dispatching S4 Methods startsWith: Does String Start or End With Another String?Startup: Initialization at Start of an R Session stop: Stop Function Execution stopifnot: Ensure the Truth of R Expressions strptime: Date-time Conversion Functions to and from Character strrep: Repeat the Elements of a Character Vector strsplit: Split the Elements of a Character Vector strtoi: Convert Strings to Integers strtrim: Trim Character Strings to Specified Display Widths structure: Attribute Specification strwrap: Wrap Character Strings to Format Paragraphs subset: Subsetting Vectors, Matrices and Data Frames substitute: Substituting and Quoting Expressions substr: Substrings of a Character Vector sum: Sum of Vector Elements summary: Object Summaries svd: Singular Value Decomposition of a Matrix sweep: Sweep out Array Summaries switch: Select One of a List of Alternatives Syntax: Operator Syntax and Precedence Sys.getenv: Get Environment Variables Sys.getpid: Get the Process ID of the R Session Sys.glob: Wildcard Expansion on File Paths Sys.info: Extract System and User Information Sys.localeconv: Find Details of the Numerical and Monetary Representations in...sys.parent: Functions to Access the Function Call Stack Sys.readlink: Read File Symbolic Links Sys.setenv: Set or Unset Environment Variables Sys.setFileTime: Set File Time Sys.sleep: Suspend Execution for a Time Interval sys.source: Parse and Evaluate Expressions from a File system: Invoke a System Command system2: Invoke a System Command system.file: Find Names of R System Files system.time: CPU Time Used Sys.time: Get Current Date and Time Sys.which: Find Full Paths to Executables t: Matrix Transpose table: Cross Tabulation and Table Creation tabulate: Tabulation for Vectors tapply: Apply a Function Over a Ragged Array taskCallback: Add or Remove a Top-Level Task Callback taskCallbackManager: Create an R-level Task Callback Manager taskCallbackNames: Query the Names of the Current Internal Top-Level Task...tempfile: Create Names for Temporary Files textconnections: Text Connections tilde: Tilde Operator timezones: Time Zones toString: Convert an R Object to a Character String trace: Interactive Tracing and Debugging of Calls to a Function or...traceback: Get and Print Call Stacks tracemem: Trace Copying of Objects transform: Transform an Object, for Example a Data Frame Trig: Trigonometric Functions trimws: Remove Leading/Trailing Whitespace try: Try an Expression Allowing Error Recovery typeof: The Type of an Object unique: Extract Unique Elements unix/Signals: Interrupting Execution of R unlink: Delete Files and Directories unlist: Flatten Lists unname: Remove 'names' or 'dimnames'UseMethod: Class Methods userhooks: Functions to Get and Set Hooks for Load, Attach, Detach and...utf8Conversion: Convert Integer Vectors to or from UTF-8-encoded Character...UTF8filepaths: File Paths not in the Native Encoding validUTF8: Check if a Character Vector is Validly Encoded vector: Vectors Vectorize: Vectorize a Scalar Function Version: Version Information warning: Warning Messages warnings: Print Warning Messages weekday.POSIXt: Extract Parts of a POSIXt or Date Object which: Which indices are TRUE?which.min: Where is the Min() or Max() or first TRUE or FALSE ?windows/shell: Invoke a System Command, using a Shell windows/shell.exec: Open a File or URL using Windows File Associations with: Evaluate an Expression in a Data Environment withVisible: Return both a Value and its Visibility write: Write Data to a File writeLines: Write Lines to a Connection xtfrm: Auxiliary Function for Sorting and Ranking zapsmall: Rounding of Numbers: Zapping Small Ones to Zero zMachine: Numerical Characteristics of the Machine zpackages: Listing of Packages zScript: Scripting Language Interface zutils: Miscellaneous Internal/Programming Utilities

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