Vector Arithmetic

source “K-MOOC 오세종 교수님의 [R 데이터 분석 입문] 강좌의 2. R 문법 기초 (1) 중 (http://www.kmooc.kr/courses/course-v1:DKUK+DKUK0003+2020_T3)”

Arithmetic Operation

d<- c(1, 4, 3, 7, 8)
2*d # multiply 2 to all elements of vector d
d-5 # subtract 5 from all elements of vector d

Link of two vectors

x<- c(1, 2, 3)
y<- c(4, 5)
c(x, y) # Simply link x and y and print out
z<- c(x, y) # Link x and y and store it to z

Arithmetic operation of two vectors

Two vectors should be same length

x<-c(1, 2, 3)
y<-c(4, 5, 6)
x+y # add counterpart elements
z<- x+y # store the values of x+y to z

Functions for Data Vector

sum(): sum of data mean(): average of data median(): median of data max(), min(): maximum data, minimum data var(): dispersion of data sd(): standard deviation of data sort(): sort the data (ascending, descending) range(): range of data (max~min) length(): number of data (length of vector)

d<- c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
sum(d)
sum(2*d) # multiply 2 to 1 to 10 and add all
length(d)
mean(d[1:5]) # mean of d[1] to d[5]
max(d)
min(d)
sort(d) # ascending
sort(d, decreasing = FALSE) # ascending
sort(d, decreasing = TRUE) # descending

v1<- median(d)
v1
v2<- sum(d)/length(d)
v2

Function

y = f(x)

d<-c(1,2, 3, 4, 5, 6, 7, 8, 9, 10)
sort(d, decreasing = FALSE) # decreasing is parameter name. d, FALSE are parameter values. parameters are divided by comma (,)
v1<- c(4, 2, 3, 1, 6, 10, 8, 9)
sort(x=v1, decreasing = TRUE) # x: parameter name (you cannot use y=v1). decreasing: 2nd parameter name (non-increasing, increasing = TRUE is wrong). Parameter names are given
sort(v1, FALSE) # sort(FALSE, v1) occurs error
sort(v1) # Use default (which is FALSE)

Use help to know parameter

Logical Operator

Compare 2 numbers to result TRUE or FALSE “<” “<=” “>” “>=” “==” “!=” “|” “&”

d<- c(1,2,3,4,5,6,7,8,9)
d>=5 # F F F F T ...
d[d>5] # d>5: 6, 7, 8, 9 print TRUE values only  
sum(d>5) # print the number of values lager than 5. TURE=1, FALSE=0
sum(d[d>5]) # d>5 print TRUE values only. Sum of 6, 7, 8, 9
d==5 # print the value equal to 5
# F F F F T F F F F
condi <- d>5 & d<8 # conditional statements can be stored in variable
# print values bigger than 5 and smaller than 8

Help

help(sum)
? sum
help.search("average")
history()

• package Call package

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