R commands

See also why use R and the RSS feed of posts labelled R.

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.


R mailing list: Use < - data-blogger-escaped-assignment="" data-blogger-escaped-comment----="" data-blogger-escaped-for="" data-blogger-escaped-functions="">

Set operations

x = letters[1:3]
y = letters[3:5]

union(x, y)
## [1] "a" "b" "c" "d" "e"
intersect(x, y)
## [1] "c"
setdiff(x, y)
## [1] "a" "b"
setdiff(y, x)
## [1] "d" "e"
setequal(x, y)
## [1] FALSE

Information about your R system

sessionInfo()

installed.packages()

Handling files

getwd()
list.files(tempdir()) 
dir.create("blabla")
read.csv("data.csv")

Lists

Given a list structure x, unlist simplifies it to produce a vector which contains all the atomic components which occur in x.

l1 <- a="a" b="2," c="pi+2i)" font="" list="" nbsp="">

unlist(l1) # a character vector

x<- 1="" br="">
x<-1

S3 methods

x<-1



List all available methods for a class:


methods(class="lm")

 One liners

Remove all objects in the workspace except one :


rm(list=ls()[!ls()=="object_to_keep"])

knitr

Those 2 commands are different.
Sets the options for chunk, within a knitr chunk inside the .Rmd document


opts_chunk$set(fig.width=10)

 Sets the options for knitr outside the .Rmd document


opts_knit$set()

dplyr

pipes

cars %>%
  group_by(speed) %>%
  print %>%
  summarise(numberofcars = n(),
            min = min(dist),
            mean = mean(dist),
            max = max(dist))

group_by() creates a tbl_df objects which is a wrapper around a data.frame to enable some functionalities. Note that print returns its output on a tbl_df object. So print() can be used inside the pipe without stopping the workflow.

 plyr (I replaced it with dplyr)

progress bar


l_ply(1:100000, identity, .progress = "win")

Rename items in a dataframe with revalue


sawnwood$item <- br="" item="" revalue="" sawnwood="">    c("Sawnwood (C)" = "Sawnwood Coniferous",
   "Sawnwood (NC)" = "Sawnwood Non Coniferous"))

Rename column names by their names





rename(mtcars, c("disp" = "displacement"))

Plotting with ggplot2

• geom_bar
• geom_tile + a gradient produce heat maps