Data Creation

Question 1

c(…)

Answer 1

generic function to combine arguments with the default forming a vector; with recursive=TRUE descends through lists combining all elements into one vector

Question 2

from:to

Answer 2

generates a sequence; “:” has operator priority; 1:4 + 1 is “2,3,4,5”

Question 3

seq(from,to)

Answer 3

generates a sequence by= specifies increment; length=

specifies desired length

Question 4

seq(along=x)

Answer 4

generates 1, 2, …, length(along); useful for for

loops

Question 5

rep(x,times)

Answer 5

replicate x times; use each= to repeat “each” el-
ement of x each times; rep(c(1,2,3),2) is 1 2 3 1 2 3;
rep(c(1,2,3),each=2) is 1 1 2 2 3 3

Question 6

data.frame(…)

Answer 6

create a data frame of the named or unnamed
arguments; data.frame(v=1:4,ch=c(“a”,”B”,”c”,”d”),n=10);
shorter vectors are recycled to the length of the longest

Question 7

list(…)

Answer 7

create a list of the named or unnamed arguments;

list(a=c(1,2),b=”hi”,c=3i);

Question 8

array(x,dim=)

Answer 8

array with data x; specify dimensions like

dim=c(3,4,2); elements of x recycle if x is not long enough

Question 9

matrix(x,nrow=,ncol=)

Answer 9

matrix; elements of x recycle

Question 10

factor(x,levels=)

Answer 10

encodes a vector x as a factor

Question 11

gl(n,k,length=n*k,labels=1:n)

Answer 11

generate levels (factors) by spec-
ifying the pattern of their levels; k is the number of levels, and n is
the number of replications

Question 12

expand.grid()

Answer 12

a data frame from all combinations of the supplied vec-

tors or factors

Question 13

rbind(…)

Answer 13

ombine arguments by rows for matrices, data frames, and others

Question 14

cbind(…)

Answer 14

id. by columns