Getting closer to the end:

- Plot 1 -> done
- Plot 2 -> done

README.md

@@ -1,2 +1,2 @@
 # ExData_Plotting2
-Plotting Assignment 1 for Exploratory Data Analysis
+Plotting Assignment 2 for Exploratory Data Analysis

plot1.R

@@ -11,3 +11,25 @@ if (!exists("SCC")) {
   SCC <- load.SCC()
 }
 
+#
+# Have total emissions from PM2.5 decreased in the United States from 1999 to 2008? 
+# 
+# Using the base plotting system, make a plot showing the total PM2.5 emission from 
+# all sources for each of the years 1999, 2002, 2005, and 2008.
+#
+
+library(dplyr)
+
+png('plot1.png', width=750, height=750)
+
+with(
+  NEI %>% 
+    group_by(year) %>% 
+    summarise(emissions = sum(Emissions)),
+  plot(year, emissions, type = "l", 
+       main = "Fine particulate matter emissions (PM2.5) in the U.S. ", 
+       xlab = "Year", 
+       ylab = "Total emissions in tons")
+)
+
+dev.off()

plot2.R

@@ -0,0 +1,32 @@
+
+# Check if we have data, if not load it!
+
+source("load.data.R")
+
+if (!exists("MEI")) {
+  NEI <- load.NEI()
+}
+
+if (!exists("SCC")) {
+  SCC <- load.SCC()
+}
+
+# Have total emissions from PM2.5 decreased in the Baltimore City, Maryland (fips == "24510") 
+# from 1999 to 2008? Use the base plotting system to make a plot answering this question.
+
+library(dplyr)
+
+png('plot2.png', width=750, height=750)
+
+with(
+  NEI %>% 
+    filter(fips == "24510") %>% 
+    group_by(year) %>% 
+    summarise(emissions = sum(Emissions)),
+  plot(year, emissions, type = "l", 
+       main = "Fine particulate matter emissions (PM2.5) in Baltimore City, Maryland", 
+       xlab = "Year", 
+       ylab = "Total emissions in tons")
+)
+
+dev.off()