R

Front 1

Matrix (N * T) into Vector.

Back 1

(i-1)*T + t

Front 2

Type of an object?

Back 2

class(obj)

Front 3

Eliminate the effect of class.

Back 3

unclass(obj)

Front 4

Levels of a factor?

Back 4

levels(factor)

Front 5

What is a data.frame?

Back 5

A list made into a matrix.

Front 6

Formating in C.

Back 6

formatC(foo, digits=3)

Front 7

Formating in C to obtain integers.

Back 7

formatC(foo, format="d")

Front 8

Intersection between two vectors.

Back 8

intersect(vec1,vec2)

Front 9

Belong to a set.

Back 9

belong(element,set)
FALSE or TRUE

Front 10

Demonstration of plotting maths.

Back 10

demo(plotmath)

Front 11

Including mathematical formulaes.

Back 11

expression()

Front 12

Combingin maths and variables.

Back 12

bquote()

Front 13

Horizontal axis labels.

Back 13

par(las=1)

Front 14

Margin intervals.

Back 14

par(mai=c(1,1,1,1))

Front 15

Direction of par(mai=c(1,1,1,1))

Back 15

bottom, left, top, right.

Front 16

Order and apply an order.

Back 16

o <- order[vec]
order.vec <- vec[o]

Front 17

Differences between two sets.

Back 17

setdiff(v1,v2)

Front 18

Select type of output in SCAN.

Back 18

scan(foo.txt, what="character)

Front 19

Add a grid to a graph.

Back 19

grid(Number_Cells_X, Number_Cells_Y, lwd=2)

Front 20

P-value from ANOVA object.

Back 20

anova$p

Front 21

F-value from ANOVA object.

Back 21

anova$F

Front 22

1:3 - 2

Back 22

c(-1,0,1)

Front 23

1:3*2

Back 23

c(2,4,6)

Front 24

Close R.

Back 24

q()

Front 25

Fit a linear model with DESIGN matrix.

Back 25

lm.fit(X[n*p], y[n])

Front 26

Fixed and Random Coefficients in LME.

Back 26

model$coefficients

Front 27

Factor to numeric

Back 27

as.numeric(as.vector(factor))

Front 28

Is a missing value?

Back 28

is.na(value)

Front 29

Max removing missing values.

Back 29

max(vec, na.rm=TRUE)

Front 30

Random/Fixed effects from a model.

Back 30

mod$coefficients

Front 31

Bash within R.

Back 31

system("mkdir foo")

Front 32

Set working directory.

Back 32

setwd()

Front 33

Suppress a letter in a string.

Back 33

strsplit( "foo\", "\")

Front 34

Write entries in one single column.

Back 34

write(foo, foo.txt, ncolumns=1)

Front 35

Matrix Product.

Back 35

A %*% B

Front 36

xAx

Back 36

x %*% A %*% x

Front 37

Matrix Inverse

Back 37

solve(A)

Front 38

xA^{-1}x

Back 38

x %*% solve(A,x)

Front 39

Permission problem when installing new package.

Back 39

chown 777 -R R

Front 40

Difference between order() and rank().

Back 40

x[order(x)] is equivalent to sort(x).
rank(x) is just the ranks.

Front 41

gedelete

Back 41

gedelete

Front 42

Difference between && and &

Back 42

&& apply to vectors of length 1.
& apply elementwise to vectors.

Front 43

Difference between || and |

Back 43

|| apply to vectors of length 1.
| apply elementwise to vectors.

Front 44

Syntax for while.

Back 44

while (condition) expr

Front 45

Maximum likelihood estimation.

Back 45

mle(-loglik)

Front 46

Plot Time series.

Back 46

plot(as.ts(mat))