Dictionary

General bits

  1. help(topic)

  2. ?topic

  3. ls()

  4. dir()

  5. list.files()

Input and output

  1. save()

  2. load()

  3. data() This function allows you to search for pre-made data sets in r ex.

?data
## starting httpd help server ... done
data()
  1. library() This code allows you to access a package and insert it into your code. Then it allows your package to work for the code chunk. ex.
library(ggplot2)
## Warning: package 'ggplot2' was built under R version 3.5.3
Names <- rep(c("Dara", "Azalea", "Barbi", "Rowena", "Fiona"),each=2)
MF <- rnorm(10, 45, 25)
Condition <- rep(c("Social", "Nonsocial"), 5)
Aversity <- rep(c("A", "N_A"), times=c(4,6))
plot_df <- data.frame (Names, MF, Condition, Aversity)

ggplot(plot_df, aes(x=Condition, y=MF, group=Names, 
                    linetype=Aversity))

  1. read.table()

  2. read.csv()

  3. scan()

  4. print() This function analyzes the results of your code (executing all the commands) ex.

data.frame(1,2,3,4)
##   X1 X2 X3 X4
## 1  1  2  3  4
print(data.frame())
## data frame with 0 columns and 0 rows

  1. cat()

  2. write.table()

Data Creation

  1. c() This function is used to combine elements (factors in a vectore for example)

  2. from:to (where from and to are replaced with numbers, e.g. 1:10)

  3. seq()

  4. rep()

  5. data.frame() This allows one to enter specific groups of data values ex.

data.frame(1, 2, 3, 5)
##   X1 X2 X3 X5
## 1  1  2  3  5

  1. list()

  2. matrix()

  3. factor()

  4. rbind()

  5. cbind() This funtion

Slicing and extracting data indexing vectors

x[n] nth element x[-n] all but nth element x[1:n] first n elements x[-(1:n)] elements from n+1 to the end x[c(1,4,2)] specific elements x[“name”] elements named “name” x[x>3] all elements greater than 3 x[x > 3 & x < 5] all elements between 3 and 5 x[x %in% c(“a”,“and”,“the”)] all elements in given set

Indexing lists

x[n] list with elements n x[[n]] nt h element of the list x[[“name”]] element of the list named “name” x$name id.

Indexing matrices

x[i,j] element at row i, column j x[i,] row i x[,j] column j x[,c(1,3)] columns 1 and 3 x[“name”,] row named “name” Indexing data frames (matrix indexing plus the following) x[[“name”]] column named “name” x$nameid.

Variable conversion

as.data.frame(x) as.numeric(x) as.logical(x) as.character(x)

Variable information

1.is.na(x) 2.is.null(x) 3.is.data.frame(x) 4.is.numeric(x) 5.is.character(x) 6.length(x) 7.dim(x) This funtion provides the number of rows and columns in a data frame without the data

library(dplyr)
## Warning: package 'dplyr' was built under R version 3.5.3
## 
## Attaching package: 'dplyr'
## The following objects are masked from 'package:stats':
## 
##     filter, lag
## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union
df <- starwars

dim(df)
## [1] 87 13

8.dimnames(x) This function lists the names of the categories in a data frame

library(dplyr)

df <- starwars

dimnames(df)
## [[1]]
##  [1] "1"  "2"  "3"  "4"  "5"  "6"  "7"  "8"  "9"  "10" "11" "12" "13" "14"
## [15] "15" "16" "17" "18" "19" "20" "21" "22" "23" "24" "25" "26" "27" "28"
## [29] "29" "30" "31" "32" "33" "34" "35" "36" "37" "38" "39" "40" "41" "42"
## [43] "43" "44" "45" "46" "47" "48" "49" "50" "51" "52" "53" "54" "55" "56"
## [57] "57" "58" "59" "60" "61" "62" "63" "64" "65" "66" "67" "68" "69" "70"
## [71] "71" "72" "73" "74" "75" "76" "77" "78" "79" "80" "81" "82" "83" "84"
## [85] "85" "86" "87"
## 
## [[2]]
##  [1] "name"       "height"     "mass"       "hair_color" "skin_color"
##  [6] "eye_color"  "birth_year" "gender"     "homeworld"  "species"   
## [11] "films"      "vehicles"   "starships"

9.nrow(x) 10.ncol(x) 11.class() 12.attributes()

Data selection and manipulation

which.max() which.min() which() sort() unique() table() sample()

Math

max() This sets the maximum value included in a data set (and graph)

min() This set the minimum value included in a data set (and graph)

range() This determines the range of numbers considered in a graph

sum() This function adds all the numbers in a given set

mean() Creates the mean of a given set of number values

median() calculates the median of a set of numbers

var() sd() cor() round() abs()

Matrices

t() diag() rowSums() colSums() rowMeans() colMeans()

Advanced Data processing

apply() aggregate() Strings paste() strsplit() tolower() toupper

Plotting

hist() This function creates a histogram graph of a given set of data

plot() This function creates a plot graph of a given set of data

Distributions

rnorm() This function inserts a normal distribution

runif()

Programming

show that you can define a function show that you can write a for loop show that you can write a while loop show that you can write an if else statement Explain what return() does inside a function, show you can use it Explain what break() does, show you can use it

Installing some packages

Use the packages tab in R-studio to install these packages. You will need to be connected to the internet when you do this. If you are installing on your laptop, or on R-studio Cloud, then these packages will not need to installed again.

ggplot2 dplyr shiny data.table reshape2 stringr