36 Importing a CSV file into an R data.frame variable

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## importing a CSV file into an R data.frame variable
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# CSV stands for "comma separated values". 
#
# A CSV file contains data that is is intended to be arranged
# in rows and columns (similar to an Excel file). Hoewver, in the 
# CSV file itself, the data is not lined up in columns. Rather
# commas separate the data that should go in different columns.
#
# Each row of the data is a line in the CSV file.
# Each value in a line is separated from the other values by commas. 
#
# EXAMPLE: The following could be the contents of a CSV file.
#
#           student,year,gender,test1,test2,final,honors
#           joe,so,m,100,100,89,TRUE
#           sam,so,m,95,93,missing,FALSE
#           sue,fr,f,80,66,68,FALSE
#           al,fr,m,59,52,42.5,FALSE
#           alice,fr,f,85,missing,missing,TRUE
#           anne,se,f,75,65,76,FALSE
#           bertha,se,f,65,58,62.5,FALSE
#           charlie,so,m,86,84,93,FALSE
#           david,so,m,78,82,88,TRUE
#           edgar,fr,m,64,68,60,FALSE
#           lou,ju,m,83,78,92.5,FALSE
#           francine,ju,f,90,91,79.5,FALSE
#           dan,ju,m,83,69,93,TRUE
#           daniella,se,f,96,100,100,FALSE
#           sarah,ju,f,80,68,78,FALSE
#           rebecca,so,f,77,83,75,FALSE
#           rachel,ju,f,80,82,86,TRUE
#           deborah,fr,f,95,100,100,FALSE


# import the file grades.csv
# - press "Import Dataset" button in Environment window
# - choose "From Text (base)"
# - choose the file
# - fill in the following values:
#   o Name :    the name of the variable that will hold your data
#   o Heading:  choose "yes" if the data has column heading (otherwise, choose "no")
#   o Separator: for csv files choose "comma" (you can choose other types of separators based on the data in the file)
#   o na.strings: choose the value in the file that indicates NA data
#   o Strings as factors:   for now make sure to UNcheck this - we will learn more about this later# - read.csv
#
# This will run the read.csv function and assign the result to the variable
# that you specified in the "Name" box. By default this will be the same name
# as the name of the file.
#
# RStudio will then run the View command to show the data in a tab in the 
# "source window" in RStudio.

# Result of following the instructions above is that the following two 
# commands will be excuted.
# - The 1st command creates a variable to hold the data.
# - The 2nd command displays the data in the source window.
#
#      grades <- read.csv("C:/Users/Home/Desktop/grades.csv", header=FALSE, stringsAsFactors=FALSE)
#      View(grades2)
#
# You can type these commands yourself but the RStudio interface makes it
# easier to remember exactly how to type the commands.

# Read the information from the file into the variable, grades.
#grades <- read.csv("C:/Users/Home/Desktop/grades.csv", header=TRUE, stringsAsFactors=FALSE)
grades

Error: object 'grades' not found

# To view the data in RStudio's source window use the View function
#
# View(grades)

# To view the data in the Console window, just type the name of the variable
grades

Error: object 'grades' not found