bham-r-code/TheFirstDaySummary.R at master · bham-carpentries/bham-r-code · GitHub

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# Data objects

#vectors
A <- c(1:3,67,23:9)
B <- c("aaf","f",LETTERS[4:5],tolower(LETTERS[20:21]))

#Matrix
C <- matrix (nrow=5, ncol=3, data=0)
D <- matrix (nrow=5, ncol=3, data="a")

#Data frame
E <- data.frame(column1=c(1:5), column2=c(rep("a",3),"d",5) )

#List
G <- list(column1=c(1:5), column2=c(rep("a",3),"d",5))

## Dimensions of data objects

length(A)
length(B)
length(C)
length(D)
length(E)
length(G)

dim(A)
dim(B)
dim(C)
dim(D)
dim(E)
dim(G)

ncol (A)
ncol (B)
ncol (C)
ncol (D)
ncol (E)
ncol (G)

nrow (A)
nrow (B)
nrow (C)
nrow (D)
nrow (E)
nrow (G)

#Indexing
A[c(1,3,4)]

C[1:2,2:3]

E[1:2, 2:3]

E[E$column2 %in% "a",]
E[E$column2=="a", ]
E[E$column2!="a", ]

E[E$column2!="a" & E$column1==4, ]

E$column1

G$column1
G[[1]]

## Reading data files
gapminder <- read.csv(file="data/gapminder-FiveYearData.csv")