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### R BASICS WORKSHOP                                    ###
### PRESENTATION 2.2: PACKAGES AND TASK VIEWS            ###
##                    (A BIT ON OPERATORS)               ###
###                                                      ###
### Center for Conservation and Sustainable Development  ###
### Missouri Botanical Garden                            ###
### Website: rbasicsworkshop.weebly.com                  ###
### Last modification: 2021-June-04                      ###
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### A. A BRIEF LOOK AT OPERATORS ###########################

# Operators are similar to functions in R because they also 
# represent actions. However, the syntax is a bit different: 
# operators are used BETWEEN values 

# The most common operators are arithmetic

# These two commands are equivalent:
sum(19, 5) # Using the function *sum*
19 + 5 # Using the operator *+*

# Other common arithmetic operators:
19-5
19*5
19/5
19^5

# A commonly used operator is *:*, which generates regular 
# sequences:
help(":")

1:10

25:4

pi:6




### B. R PACKAGES ##########################################

# PACKAGES are bundles of functions (and optionally 
# datasets) that can be used as extensions to the defaults 
# available in R

# Most packages are available at: 
# http://cran.r-project.org/web/packages/

# For a package to be used, first it needs to be installed 
# using *install.pacakges*
install.packages("vegan")

# Then, every time it needs to be used, the package needs 
# to be loaded with *library*
library("vegan")

help("vegan")

# Packages can be updated with *update.packages*
update.packages("vegan")




### C. R PACKAGES AND TASK VIEWS ###########################

# TASK VIEWS are collections of packages needed for 
# specific types of analyses (e.g. genetic or spatial 
# analyses)

# Task views can be seen at: 
# http://cran.r-project.org/web/views/


# All the packages in a task view can be installed with 
# *install.views*.

# *install.views* is in the package *ctv* which needs to be 
# installed and loaded

install.packages("ctv")
library("ctv")

# install.views("Econometrics") # Installing task views can 
# take a long time