(This article was first published on

The R programming language includes many abbreviations. Abbreviations exist in function names, argument names, and allowed values for arguments. This post expands on over 150 R abbreviations with the aim of making it easier for users new to R who are trying to memorise R commands. **Jeromy Anglim's Blog: Psychology and Statistics**, and kindly contributed to R-bloggers)#### Context

Abbreviations save time when typing and can make for less cumbersome code. However, abbreviations often make it more difficult to remember a command. This is especially true when the user does not know what the abbreviation stands for.R has been developed by a group of technical experts with backgrounds in Linux and Unix, mathematics, statistics, and statistical computing. With gaining popularity, R is now being used by people with little to none of this background. Abbreviations which are intuitive to the experts are not necessarily intuitive to this broader audience. The R help system does a reasonable job of explaining the abbreviations in R. However, I thought it would be useful to write a post listing some of the common abbreviations along with the expansion of the abbreviation. Whereas R sometimes errs on the side of assuming expertise, I thought I'd err on the side of assuming naivety. Thus, the table includes many abbreviations which are probably obvious to most readers.

#### Table of R Commands

R Command | Abbreviation Expanded | Comments |

`ls` | [L]i[S]t objects | common command in Unix-like operating systems |

`rm` | [R]e[M]ove objects | common command in Unix-like operating systems |

`str` | [STR]ucture of an object | |

`unz` | [UNZ]ip | |

`getwd` | [GET] [W]orking [D]irectory | |

`dir` | [DIR]ectory | |

`sprintf` | [S]tring [PRINT] [F]ormatted | |

`c` | [C]ombine values | |

`regexpr` | [REG]ular [EXPR]ession | Why "regular"? See regular sets, regular language |

`diag` | [DIAG]onal values of a matrix | |

`col` | [COL]umn | |

`lapply` | [L]ist [APPLY] | Apply function to each element and return a list |

`sapply` | [S]implify [APPLY ] | Apply function to each element and attempt to return a vector (i.e., a vector is "simpler" than a list) |

`mapply` | [M]ultivariate [APPLY] | Multivariate version of sapply |

`tapply` | [T]able [APPLY] | Apply function to sets of values as defined by an index |

`apply` | [APPLY] function to sets of values as defined by an index | |

`MARGIN = 1 or 2 in apply` | rows [1] come before columns [2] | e.g., a 2 x 3 matrix has 2 rows and 3 columns (note: row count is stated first) |

`rmvnorm` | [R]andom number generator for [M]ulti[V]ariate [NORM]al data | |

`rle` | [R]un [L]ength [E]ncoding | |

`ftable` | [F]ormat [TABLE] | |

`xtabs` | Cross (i.e., [X]) [TAB]ulation | [X] is the symbol of a cross; [X] is sometimes spoken as "by". Cross-tabulating means to cross one variable with another |

`xtable` | [TABLE] of the object [X] | |

`formatC` | [FORMAT] using [C] style formats | i.e., [C] the programming language |

`Sweave` | [S] [WEAVE] | The R Programming language is a dialect of S. Weaving involves combining code and documentation |

`cor` | [COR]relation | |

`ancova` | [AN]alysis [O]f [COVA]riance | |

`manova` | [M]ultivariate [AN]alysis [O]f [VA]riance | |

`aov` | [A]nalysis [O]f [V]ariance | |

`TukeyHSD` | [T]ukey's [H]onestly [S]ignificant [D]ifference | |

`hclust` | [H]ierarchical [CLUST]er analysis | |

`cmdscale` | [C]lassical metric [M]ulti[D]imensional [SCAL]ing | |

`factanal` | [FACT]or [ANAL]ysis | |

`princomp` | [PRIN]cipal [COMP]onents analysis | |

`prcomp` | [PR]incipal [COMP]onents analysis | |

`lme` | [L]inear [M]ixed [E]ffects model | |

`resid` | [RESID]uals | |

`ranef` | [RAN]dom [EF]fects | |

`anova` | [AN]alysis [O]f [VA]riance | |

`fixef` | [FIX]ed [EF]ffects | |

`vcov` | [V]ariance-[COV]ariance matrix | |

`logLik` | [LOG] [LIK]elihood | |

`BIC` | [B]ayesian [I]nformation [C]riteria | |

`mcmcsamp` | [M]arkov [Chain] [Monte] [C]arlo [SAMP]ling | |

`eval` | [EVAL]uate an R expression | |

`cat` | con[CAT]enate | standard Unix command |

`apropos` | Search documentation for a purpose or on a topic (i.e., [APROPOS]) | Unix command for search documentation; |

`read.csv` | [READ] a file in [C]omma [S]eperated [V]alues format | i.e., in each row of the data commas separate values for each variable |

`read.fwf` | [READ] a file in [F]ixed [W]idth [F]ormat | |

`seq` | Generate [SEQ]uence | |

`rep` | [REP]licate values of x | perhaps also [REP]eat |

`dim` | [DIM]ension of an object | Typically, number of rows and columns in a matrix |

`gl` | [G]enerate factor [L]evels | |

`rbind` | [R]ows [BIND] | |

`cbind` | [C]olumns [BIND] | |

`is.na` | [IS] [N]ot [A]vailable | |

`nrow` | [N]umber of [ROW]s | |

`ncol` | [N]umber of [COL]umns | |

`attr` | [ATTR]ibute | |

`rev` | [REV]erse | |

`diff` | [DIFF]erence between x and a lag of x | |

`prod` | [PROD]uct | |

`var` | [VAR]iance | |

`sd` | [S]tandard [D]eviation | |

`cumsum` | [CUM]ulative [SUM] | |

`cumprod` | [CUM]ulative [PROD]uct | |

`setdiff` | [SET] [DIFF]erence | |

`intersect` | [INTERSECT]ion | |

`Re` | [RE]al part of a number | |

`Im` | [IM]aginary part of a number | |

`Mod` | [MOD]ulo opertion | remainder of division of one number by another |

`t` | [T]ranspose of a vector or matrix | |

`substr` | [SUBSTR]ing | |

`strsplit` | [STR]ing [SPLIT] | |

`grep` | [G]lobal / [R]egular [E]xpression / [P]rint | Etymology based on text editor instructions in programs such as ed |

`sub` | [SUB]stitute identified pattern found in string | |

`gsub` | [G]lobal [SUB]stitute identified pattern found in string | |

`pmatch` | [P]artial string [MATCH]ing | |

`nchar` | [N]umber of [CHAR]acters in a string | |

`ps.options` | [P]ost-[S]cript [OPTIONS] | |

`win.metafile` | [WIN]dows [METAFILE] graphic | |

`dev.off` | [DEV]ice [OFF] | |

`dev.cur` | [CUR]rent [DEV]ice | |

`dev.set` | [SET] the current [DEV]ice | |

`hist` | [HIST]ogram | |

`pie` | [PIE] Chart | |

`coplot` | [CO]nditioning [PLOT] | |

`matplot` | [PLOT] colums of [MAT]rices | |

`assocplot` | [ASSOC]iation [PLOT] | |

`plot.ts` | [PLOT] [T]ime [S]eries | |

`qqnorm` | [Q]uantile-[Q]uantile [P]lot based on normal distribution | |

`persp` | [PERSP]ective [P]lot | |

`xlim` | [LIM]it of the [X] axis | |

`ylim` | [LIM]it of the [Y] axis | |

`xlab` | [LAB]el for the [X] axis | |

`ylab` | [LAB]el for the [Y] axis | |

`main` | [MAIN] title for the plot | |

`sub` | [SUB] title for the plot | |

`mtext` | [M]argin [TEXT] | |

`abline` | [LINE] on plot often of the form y = [A] + [B] x | |

`h argument in abline` | [H]orizontal line | |

`v argument in abline` | [V]ertical line | |

`par` | Graphics [PAR]ameter | |

`adj as par` | [ADJ]ust text [J]ustification | |

`bg as par` | [B]ack[G]round colour | |

`bty as par` | [B]ox [TY]pe | |

`cex as par` | [C]haracter [EX]tension or [EX]pansion of plotting objects | |

`cex.sub as par` | [C]haracter [EX]tension or [EX]pansion of [SUB]title | |

`cex.axis as par` | [C]haracter [EX]tension or [EX]pansion of [AXIS] annotation | |

`cex.lab as par` | [C]haracter [EX]tension or [EX]pansion X and Y [LAB]els | |

`cex.main as par` | [C]haracter [EX]tension or [EX]pansion of [MAIN] title | |

`col as par` | Default plotting [COL]our | |

`las as par` | [L]abel of [A]xis [S]tyle | |

`lty as par` | [L]ine [TY]pe | |

`lwd as par` | [L]ine [W]i[D]th | |

`mar as par` | [MAR]gin width in lines | |

`mfg as par` | Next [G]raph for [M]atrix of [F]igures | |

`mfcol as par` | [M]atrix of [F]igures entered [COL]umn-wise | |

`mfrow as par` | [M]atrix of [F]igures entered [ROW]-wise | |

`pch as par` | [P]lotting [CH]aracter | |

`ps as par` | [P]oint [S]ize of text | Point is a printing measurement |

`pty as par` | [P]lot region [TY]pe | |

`tck as par` | [T]i[CK] mark length | |

`tcl as par` | [T]i[C]k mark [L]ength | |

`xaxs as par` | [X] [AX]is [S]tyle | |

`yaxs as par` | [Y] [AX]is [S]tyle | |

`xaxt as par` | [X] [AX]is [T]ype | |

`yaxt as par` | [Y] [AX]is [T]ype | |

`asp as par` | [ASP]ect ratio | |

`xlog as par` | [X] axis as [LOG]arithm scale | |

`ylog as par` | [Y] axis as [LOG]arithm scale | |

`omi as par` | [O]uter [M]argin width in [I]nches | |

`mai as par` | [MA]rgin width in [I]nches | |

`pin as par` | [P]lot size in [IN]ches | |

`xpd as par` | Perhaps: [X = Cut] [P]lot ? Perhaps D for device | |

`xyplot` | [X] [Y] [PLOT] | [X] for horizontal axis; [Y] for vertical axis |

`bwplot` | [B]ox and [W]hisker plot | |

`qq` | [Q]uantile-[Quantile] plot' | |

`splom` | [S]catter[PLO]t [M]atrix | |

`optim` | [OPTIM]isation | |

`lm` | [L]inear [M]odel | |

`glm` | [G]eneralised [L]inear [M]odel | |

`nls` | [N]onlinear [L]east [S]quare parameter esetimation | |

`loess` | [LO]cally [E]stimated [S]catterplot [S]moothing | |

`prop.test` | [TEST] null hypothesis that [PROP]ortions in several gropus are the same | |

`rnorm` | [R]andom number drawn from [NORM]al distribution | |

`dnorm` | [D]ensity of a given quantile in a [NORM]al distribution | |

`pnorm` | [D]istribution function for [NORM]al distribution returning cumulaive [P]robability | |

`qnorm` | [Q]uantile function based on [NORM]al distribution | |

`rexp` | [R]andom number generation from [EXP]onential distribution | |

`rgamma` | [R]andom number generation from [GAMMA] distribution | |

`rpois` | [R]andom number generation from [POIS]on distribution | |

`rweibull` | [R]andom number generation from [WEIBULL] distribution | |

`rcauchy` | [R]andom number generation from [CAUCHY] distribution | |

`rbeta` | [R]andom number generation from [BETA] distribution | |

`rt` | [R]andom number generation from [t] distribution | |

`rf` | [R]andom number generation from [F] distribution | F for Ronald [F]isher |

`rchisq` | [R]andom number generation from [CHI] [SQ]uare distribution | |

`rbinom` | [R]andom number generation from [BINOM]ial distribution | |

`rgeom` | [R]andom number generation from [EXP]onential distribution | |

`rhyper` | [R]andom number generation from [HYPER]geometric distribution | |

`rlogis` | [R]andom number generation from [LOGIS]tic distribution | |

`rlnorm` | [R]andom number generation from [L]og [NOR]mal distribution | |

`rnbinom` | [R]andom number generation from [N]egative [BINOM]ial distribution | |

`runif` | [R]andom number generation from [UNIF]orm distribution | |

`rwilcox` | [R]andom number generation from [WILCOX]on distribution | |

`ggplot in ggplot2` | [G]rammar of [G]raphics [PLOT] | See Leland Wilkinson (1999) |

`aes in ggplot2` | [AES]thetic mapping | |

`geom_ in ggplot2` | [GEOM]etric object | |

`stat_ in ggplot2` | [STAT]istical summary | |

`coord_ in ggplot2` | [COORD]inate system | |

`qplot in ggplot2` | [Q]uick [PLOT] | |

`x as argument` | [X] is common letter for unknown variable in math | |

`FUN as argument` | [FUN]ction | |

`pos as argument` | [POS]ition | |

`lib.loc in library` | [LIB]rary folder [LOC]ation | |

`sep as argument` | [SEP]erator character | |

`comment.char in read.table` | [COMMENT] [CHAR]acter(s) | |

`I` | [I]nhibit [I]nterpretation or [I]nsulate | |

`T value` | [T]rue | |

`F value` | [F]alse | |

`na.rm as argument` | [N]ot [A]vailable [R]e[M]oved | |

`fivenum` | [FIVE] [NUM]ber summary | |

`IQR` | [I]nter [Q]uartile [R]ange | |

`coef` | Model [COEF]ficients | |

`dist` | [DIST]ance matrix | |

`df as argument` | [D]egrees of [F]reedom | |

`mad` | [M]edian [A]bsolute [D]eviation | |

`sink` | Divert R output to a connection (i.e., like connecting a pipe to a [SINK]) | |

`eol in write.table` | [End] [O]f [L]ine character(s) | |

`R as software` | [R]oss Ihaka and [R]obert Gentleman or [R] is letter before S | |

`CRAN as word` | [C]omprehensive [R] [A]rchive [N]etwork | As I understand it: Inpsired by CTAN (Comprehensive TeX Archive Network); pronunciation of CRAN rhymes with CTAN (i.e., "See" ran as in Iran; "See tan") |

`Sexpr` | [S] [EXPR]ession | |

`ls.str` | Show [STR]ucture of [L]i[S]ted objects | |

`browseEnv` | [BROWSE] [ENV]ironment | |

`envir as argument` | [ENVIR]onment | |

`q` | [Q]uit | |

`cancor` | [CAN]onical [COR]relation | |

`ave` | [AVE]rage | |

`min` | [MIN]imum | |

`max` | [MAX]imum | |

`sqrt` | [SQ]uare [R]oo[T] | |

`%o%` | [O]uter product | |

`&` | & is ampersand meaning [AND] | |

`|` | | often used to represent OR in computing (http://en.wikipedia.org /wiki /Logical_disjunction) | |

`:` | sequence generator; aslo used in MATLAB | |

`nlevels` | [N]umber of [LEVELS] in a factor | |

`det` | [DET]erminant of a matrix | |

`crossprod` | Matrix [CROSSPROD]uct | |

`gls` | [G]eneralised [L]east [S]quares | |

`dwtest in lmtest` | [D]urbin-[W]atson Test | |

`sem in sem` | [S]tructural [E]quation [M]odel | |

`betareg in betareg` | [BETA] [REG]ression | |

`log` | Natural [LOG]arithm | Default base is e consistent with most mathematics (http://en.wikipedia.org /wiki /Logarithm#Implicit_bases) |

`log10` | [LOG]arithm base 10 | |

`fft` | [F]ast [F]ourier [T]ransform | |

`exp` | [EXP]onential function | i.e., e^x |

`df.residual` | [D]egrees of [F]reedom of the [R]esidual | |

`sin` | [SIN]e function | |

`cos` | [COS]ine function | |

`tan` | [TAN]gent function | |

`asin` | [A]rc[SIN]e function | |

`acos` | [A]rc[COS]ine function | |

`atan` | [A]rc[TAN]gent function | |

`deriv` | [DERIV]ative | |

`chol` | [Choleski] decomposition | |

`chol2inv` | [CHOL]eski [2=TO] [INV]erse | |

`svd` | [S]ingular [V]alue [D]ecomposition | |

`eigen` | [EIGEN]value or [EIGEN]vector | |

`lower.tri` | [LOWER] [TRI]angle of a matrix | |

`upper.tri` | [UPPER] [TRI]angle of a matrix | |

`acf` | [A]uto [C]orrelation or [C]ovariance [F]unction | |

`pacf` | [P]artial A]uto [C]orrelation or [C]ovariance [F]unction | |

`ccf` | [C]ross [C]orrelation or [C]ovariance [F]unction | |

`Rattle as software` | [R] [A]nalytical [T]ool [T]o [L]earn [E]asily | Perhaps, easy like a baby's rattle |

`StatET as software` | Anyone know? Statistics Eclipse? | |

`JGR as software` | [J]ava [G]UI for [R] | pronounced "Jaguar" like the cat |

`ESS as software` | [E]macs [S]peaks [S]tatistics | |

`Rcmdr package` | [R] [C]o[m]man[d]e[r] GUI | |

`prettyNum` | [PRETTY] [NUM]ber | |

`Inf value` | [Inf]inite | |

`NaN value` | [N]ot [A] [N]umber | |

`is.nan` | [IS] [N]ot [A] [N]umber | |

`S3` | R is a dialect of [S]; 3 is the version number | |

`S4` | R is a dialect of [S]; 4 is the version number | |

`Rterm as program` | [R] [TERM]inal | |

`R CMD as program` | I think: [R] [C]o[m]man[D] prompt | |

`repos as option` | [REPOS]itory locations | |

`bin folder` | [BIN]aries | Common Unix folder for "essential command binaries" |

`etc folder` | [et cetera] | Common Unix folder for "host-specific system-wide configuration files |

`src folder` | [S]ou[RC]e [C]ode | Common Unix folder |

`doc folder` | [DOC]umentation | |

`RGUI program` | [R] [G]rapical [U]ser [I]nterface | |

`.site file extension` | [SITE] specific file | e.g., RProfile.site |

`Hmisc package` | Frank [HARRELL]'s package of [MISC]elaneous functions | |

`n in debug` | [N]ext step | |

`c in debug` | [C]ontinue | |

`Q in debug` | [Q]uit | |

`MASS package` | [M]odern [A]pplied [S]tatistics with [S] | Based on book of same name by Venables and Ripley |

`plyr package` | PL[Y=ie][R] | Double play on words: (1) package manipulates data like pliers manipulate materials; (2) last letter is R as in the program |

`aaply` | input [A]rray output [A]rray using [PLY]r package | |

`daply` | input [D]ata frame output [A]rray using [PLY]r package | |

`laply` | input [L]ist output [A]rray using [PLY]r package | |

`adply` | input [A]rray output [D]ata frame using [PLY]r package | |

`alply` | input [A]rray output [L]ist using [PLY]r package | |

`a_ply` | input [A]rray output Discarded (i.e., _ is blank) using [PLY]r package | |

`RODBC package` | [R] [O]bject [D]ata[B]ase [C]onnectivity | |

`psych package` | [PSYCH]ology related functions | |

`zelig package` | "Zelig is named after a Woody Allen movie about a man who had the strange ability to become the physical and psychological reflection of anyone he met and thus to fit perfectly in any situation." - http://gking. harvard.edu/ zelig/ | |

`strucchange package` | [STRUC]tural [CHANGE] | |

`relaimpo package` | [RELA]tive [IMPO]rtance | |

`car package` | [C]ompanion to [A]pplied [R]egression | Named after book by John Fox |

`OpenMx packge` | [OPEN] Source [M]atri[X] algebra interpreter | Need confirmation that [Mx] means matrix |

`df in write.foreign` | [D]ata [F]rame | |

`GNU S word` | [GNU] is [N]ot [U]nix [S] | |

`R FAQ word` | R [F]requently [A]sked [Q]uestions | |

`DVI format` | [D]e[V]ice [I]ndependent file format | |

`devel word` | [DEVEL]opment | as in code under development |

`GPL word` | [G]eneral [P]ublic [L]icense | |

`utils package` | [UTIL]itie[S] | |

`mle` | [M]aximum [L]ikelihood [E]stimation | |

`rpart package` | [R]ecursive [PART]itioning | |

`sna package` | [S]ocial [N]etwork [A]nalysis | |

`ergm package` | [E]xponential [R]andom [G]raph [M]odels | |

`rbugs package` | [R] interface to program [B]ayesian inference [Using] [G]ibbs [S]ampling |

#### Concluding Comments

I thank Tom Short for his R reference Card which provided some inspiration for a starting list of R commands. Feel free to reproduce or adapt this table elsewhere. For example, perhaps it could be included in an R Wiki with additional entries. If you spot an error in the table, let me know in the comments of this post.I might expand the table in the future. At the moment, it's mainly function names with not many arguments or values of arguments. I also haven't put much time into grouping and ordering the functions.

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