How to find a list of all R packages
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 Step 1: go to https://www.r-project.org/

 Step 2: Click CRAN under download
         https://cran.r-project.org/mirrors.html

 Step 3: Choose a mirror server

 Step 4: click 'packages' on the left-hand side

 Step 5: you will find two lists
         
         Table of available packages, sorted by date of publication

         Table of available packages, sorted by name

  [any one will be fine]

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Finding the manual for a specific package
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For example, to find the pdf manual for fImport, we have the following steps


   Step 1: http://www.r-project.org/

   Step 2: click 'CRAN'  

   Step 3: choose a 'mirror'

   Step 4: click 'packages' on the left-hand 

   Step 5: using Ctrl-f to search 'fImport'

   Step 6: download the pdf manual

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loaded vs. preinstalled packages
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  A loaded R package: you can use it

  A preinstalled R package is the condition 

    that you could load it

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Load and unload an R package 
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There are several ways to load an R package. 

 1) library(fImport)
 2) require(fImport)
 3) click 'Packages...' on the menu bar
    then 'load package...'

To unload an R package 
-------------------------
   We use detach() function   
  
        detach(package:XML)

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To find out all loaded R packages
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  > search()

  [1] ".GlobalEnv"       "package:stats"    "package:graphics" 

  [4] "package:grDevices" "package:datasets"  "package:utils"    

  [7] "package:methods"   "Autoloads"         "package:base"     

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Find out all preinstalled R packages
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 > library()
Packages in library  C:/Users/yany/Documents/R/win-library/3.3 :

animation               A Gallery of Animations in Statistics and
                        Utilities to Create Animations
assertthat              Easy pre and post assertions.
base64enc               Tools for base64 encoding
BB                      Solving and Optimizing Large-Scale Nonlinear
                        Systems

 (more ....) 
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