Exercise 1

v1=c(1,3,6,9,12)
v2=c(1,0,1,0,1)
v1+v2
## [1]  2  3  7  9 13
v1-v2
## [1]  0  3  5  9 11
v1*v2
## [1]  1  0  6  0 12
v1/v2
## [1]   1 Inf   6 Inf  12

Exercise 2

v3=c(0,1,2,3)
v4=c("aa", "bb","cc", "dd")
v5=c("aa", 1,"cc", 2)
str(v3)
##  num [1:4] 0 1 2 3
str(v4)
##  chr [1:4] "aa" "bb" "cc" "dd"
str(v5)
##  chr [1:4] "aa" "1" "cc" "2"

Exercise 3

geno1 = c('AA', 'AA', 'AG', 'GG', 'GG')
geno2 = c('AA', 'AA', 'GG', 'GG', 'GG')
A <- cbind(geno1,geno2)
A
##      geno1 geno2
## [1,] "AA"  "AA" 
## [2,] "AA"  "AA" 
## [3,] "AG"  "GG" 
## [4,] "GG"  "GG" 
## [5,] "GG"  "GG"
table(A)
## A
## AA AG GG 
##  4  1  5

Exercise 4

treatment1 <- c(0,1,2,3,4)
treatment2 <- c(0,2,4,6,8)
treatment3 <- c(0,3,6,9,12)
time <- c(0,2,3,6,8)
exper=data.frame(time,treatment1,treatment2,treatment3)
exper
##   time treatment1 treatment2 treatment3
## 1    0          0          0          0
## 2    2          1          2          3
## 3    3          2          4          6
## 4    6          3          6          9
## 5    8          4          8         12
plot(exper$time, exper$treatment3)

Exercise 5

completeSNP=read.table("23andMe_complete.txt", header = TRUE, sep = "\t")
str(completeSNP$chromosome)
##  Factor w/ 25 levels "1","10","11",..: 1 1 1 1 1 1 1 1 1 1 ...

In this case, chromosome is a factor with 25 levels, while in the example data, chromosome is an integer.

Exercise 6

table(completeSNP$genotype)
## 
##     --      A     AA     AC     AG     AT      C     CC     CG     CT 
##  21109   6676 147157  25036 109001    569   7188 173264   1003 108992 
##      D     DD     DI      G     GG     GT      I     II      T     TT 
##     36    157     17   7061 173054  24727    113    685   6643 148126

Exercise 7

onlyA=subset(completeSNP, completeSNP$genotype == 'A') 
table(onlyA$chromosome)
## 
##    1   10   11   12   13   14   15   16   17   18   19    2   20   21   22 
##    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0 
##    3    4    5    6    7    8    9   MT    X    Y 
##    0    0    0    0    0    0    0  732 5782  162