plot2.R

####
# 
# Author: Toby Patterson
# File: plot2.R
# Date: 7 August 2014
#
# Plots the relationship between days of week and Global Active Power (in kilowatts)
# Presumes the file project1_datafile.Rda exists in the same directory.
#
####

# Read in the table data
# Note you may need to run generate_datafile.R if this file does not exist
data_file = 'project1_datafile.Rda'
if ( !file.exists(data_file)) {
  stop('Run generate_datafile.R to create the project working datafile.')
}

# We're save
power = load(data_file)

# Output to file
canvas_size = 480
png( 
  file="plot2.png",
  height = canvas_size, 
  width=canvas_size
)
plot(
  data$DateTime,
  data$Global_active_power, 
  ylab='Global Active Power (kilowatts)',
  xlab='',
  type='l'
)

# Yes I do want this
mtext('generated by Toby Patterson, 7 Sept 2014',1,4,cex=.5)

# Detatch
dev.off()