-01-introduction

Link to the module:

Module01-Introduction

mtcars 
?sum 
hist(mtcars$mpg) 
avg_mpg <- mean(mtcars$mpg) 
avg_mpg
random_numbers <-runif(25) 
random_numbers
history()

# provides details for specific function 
help(sqrt) 
# provides same information as 
help(functionname) 
?sqrt 
# provides examples for said function 
example(sqrt) 
example(sum)

# get your current working directory 
getwd() 
# set your working directory 
#setwd("C:/Users/cevi herdian/Documents/MEGA/Data-Sciences/R Programming
#/uc-github.io/Intro to R Bootcamp/Module 01")

# Uses PEMDAS convention for order of operations 
4 + 3 / 10 ^ 2 
4 + (3 / 10 ^ 2) 
(4 + 3) / 10 ^ 2 
1 / 17 ^ 7 
1 / 0 
Inf - Inf 

#THE ASSIGNMENT (<-) OPERATOR
x <- 3     # GOOD 
x = 3      # BAD
# we can increment (build onto) existing objects
rm(list=ls())
x <- x + 1             
x 

D <- 1000 
K <- 5 
h <- .25 
Q <- sqrt((2 * D * K) / h) 
Q 

# list all objects ls() 
ls()
# remove defined object from the environment 
rm(D) 

# removes everything in the working environment -- 
# use with caution! 
rm(list = ls())

#PACKAGES
#CRAN: 10,000+ 
#Bioconductor:  1,000+ 
#GitHub: Many more plus beta versions for updated 
#packages not yet published

#So how do we install these packages?
# install packages from CRAN 
#install.packages("packagename") 

# install packages from Bioconductor 
# only required the first time biocLite()
#source("http://bioconductor.org/biocLite.R")           
# only required the first time 
#biocLite("packagename") 

# install packages from GitHub 
#install.packages("devtools")  # only required the first time 
#devtools::install_github("username/packagename")

#YOUR TURN!
#Download these packages from CRAN: tidyverse nycflights13 

install.packages("tidyverse") 
install.packages("nycflights13")
# alternative install.packages(c(“tidyverse”, “nycflights13”))

#PACKAGES:
#Loading packages: 
# load the package to use in the current R session 
library(tidyverse) 

# use a particular function within a package without loading the package 
stringr::str_replace()

#Getting help on packages: 
# provides details regarding contents of a package
help(package = "tidyr") 
# list vignettes available for a specific package 
vignette(package = "tidyr") 
# view specific 
#vignette is an R jargon for documentation
#vignette(tidy-data)--->XXXXX??

#######FUNCTIONS TO REMEMBER
#help(), ?, example()