How to use variables and Data Frames in R

In [1]:
# ------------------------------------------------------------------------------
# How to use variables and Data Frames in R
# ------------------------------------------------------------------------------

# integer
i <- 23; print(i)

# double
d <- 2.3; print(d)

# string
s <- 'hello world'; print(s)

# boolean
b <- TRUE; print(b)

# create a list
a <- list(a1=1, a2=2, a3=3) 
print(a); print(a$a1);print(a$a2);print(a$a3)

# add a named item to a list
a$a4=4; print(a); print(a$a4)

# create a vector using the c() function
v <- c(98, 99, 100)
print(v); print(v[1:2])

# create a vector from a range of integers
r <- (1:10)
print(r); print(r[5:10])

# add a new item to the end of a vector
v <- c(1, 2, 3); print(v)
v[4] <- 4; print(v)

# Create a 4-row, 3-column matrix with named headings
data <- c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
headings <- list(NULL, c("a","b","c"))
m <- matrix(data, nrow=4, ncol=3, byrow=TRUE, dimnames=headings)

print(m)
print(m[3,])
print(m[,2])

# create a new data frame
years <- c(1980, 1985, 1990)
scores <- c(34, 44, 83)
df <- data.frame(years, scores)
dim(df); print(df)
print(df[,1]); print(df$years)

[1] 23
[1] 2.3
[1] "hello world"
[1] TRUE
$a1
[1] 1

$a2
[1] 2

$a3
[1] 3

[1] 1
[1] 2
[1] 3
$a1
[1] 1

$a2
[1] 2

$a3
[1] 3

$a4
[1] 4

[1] 4
[1]  98  99 100
[1] 98 99
 [1]  1  2  3  4  5  6  7  8  9 10
[1]  5  6  7  8  9 10
[1] 1 2 3
[1] 1 2 3 4
      a  b  c
[1,]  1  2  3
[2,]  4  5  6
[3,]  7  8  9
[4,] 10 11 12
a b c 
7 8 9 
[1]  2  5  8 11
  1. 3
  2. 2
  years scores
1  1980     34
2  1985     44
3  1990     83
[1] 1980 1985 1990
[1] 1980 1985 1990
In [ ]: