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############### PRESENTATION 0 ###############
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############# R as a calculator #############
# Adding
1+1
# Subtracting
2-1
# Multiplication
3*3
# Division
15/3
# Exponentiation
10^2
# Base-2 logarithm
log2(20)
# Base-10 logarithm
log10(20)
############# Define objects #############
a <- 5
b <- 3
a
b
a + b
c <- a + b
c
### Check objects in environment
ls()
### Remove something:
rm(c)
############# Basic Data Types and Structures #############
# Numeric
num1 <- 5 # assignment (stores the value)
num1 # printing (shows the stored value)
# Access data type or structure with the class() function
class(num1)
# Character
char1 <- "Hello World!"
char1
class(char1)
# A vector of numeric values
vector1 <- c(1, 2, 4, 6, 8, 2, 5, 7)
vector1
# Access data type or structure with the class() function
class(vector1)
############# R packages #############
# R packages are collections of functions written by R developers and super users
# and they make our lives much easier. Functions used in the same type
# of R analysis/pipeline are bundled and organized in packages. In order to use a package
# we need to download and install it on our computer. Most R packages are stored
# and maintained on the CRAN https://cran.r-project.org/mirrors.html repository.
# Install a package
# install.packages('tidyverse') # run once (not every session)
# Load packages
library(tidyverse) # run each time you start R
# There is a help page for each package to tell us which functions
# it contains and which arguments go into these.
# Query package
?tidyverse
# Query function from package
?dplyr::select
############# Functions #############
# Summing a vector
?sum
sum(vector1)
# Mean of vector
?mean
mean(vector1)
mean(vector1) # mean/average
median(vector1) # median
sd(vector1) # standard deviation
sum(vector1) # sum
min(vector1) # minimum value
max(vector1) # maximum value
length(vector1) # length of vector