googleVis — NASA’s exploration of Mars

August 29, 2012

(This article was first published on Tony's bubble universe » R, and kindly contributed to R-bloggers)

After generating a few interactive charts with googleVis, I realized that it’s a great way to visualize numeric data, especially multi-dimentional data. Days ago, my colleague sent me a picture taken by Curiosity from Mars. He was crazy about it and claimed that this is the real science human should do. To be honest, I’m not as a big fan as he is. And I always believe that human won’t go anywhere unless we fix our problems here on earth. But still, I was glad to see NASA’s Curiosity successfully landing on Mars.

Thus, I decided to look into the NASA’s yearly budget and their progresses in Mars exploration. Both the data is available on wikipedia (NASA budget and Exploration of Mars). For this time, I directly read these data into R using readHTMLTable(), as Einar commented. Thereafter, raw data was modified to satify googleVis requirement. And finally, the chart was generated using gvisAnnotatedTimeLine(), with Date, budget (nominal and 2007 constant) , events in mars exploring history, etc. I even added three future programs, MAVEN, Insight and Red Dragon, in the future time line. The following is the snapshot; click here for the interactive chart. Hope you enjoy it!

Note: the blue line is the budget amounts in nominal million dollars; the red line is those in 2007 constant million dollars. And the original code is listed below.

^?View Code RSPLUS

library(XML)
# prepare the budget data
url <- "http://en.wikipedia.org/wiki/Budget_of_NASA"
budget <- readHTMLTable(url)  # retrieve data table from url
budget <- rbind(budget[[5]], budget[[6]])
colnames(budget)[2:4] <- c("Nominal", "Percentage in Federal Budget", "2007 Constant")
budget <- as.matrix(budget)
mt <- grepl("^\\d", budget[, "Year"])  # remove lines that don't start with digits (year)
budget <- budget[mt, ]
budget <- gsub("\\s*[[\\(].*[]\\)]\\s*", "", budget)  # remove '()' or '[]' comments
budget <- budget[1:(dim(budget)[1]-3), ]  # remove 2013-2015 est.
budget$Date <- as.Date(paste(budget$Year, "-1-1", sep = ""))
budget$Nominal <- as.numeric(sub(",", "", budget$Nominal))
budget[, "2007 Constant"] <- as.numeric(sub(",", "", budget[, "2007 Constant"]))
 
budget.nominal <- budget[, c("Date", "Nominal")]
budget.nominal$id <- "Nominal"
colnames(budget.nominal)[2] <- "Budget"
budget.constant <- budget[, c("Date", "2007 Constant")]
budget.constant$id <- "Constant 2007"
colnames(budget.constant)[2] <- "Budget"
dat <- rbind(budget.nominal, budget.constant)
dat <- rbind(budget.nominal, budget.constant)
dat$Type <- NA
dat$Annot <- NA  # budget data is ready
# prepare the events data
url.mars <- "http://en.wikipedia.org/wiki/Exploration_of_Mars"
mars <- readHTMLTable(url.mars)[[9]]
mt <- grepl('[Ss]uccess', mars$Result)  # remove failed events
mars <- mars[mt, -4]  # remove the terminated date
colnames(mars) <- c('mission', 'launched', 'arrived', 'type', 'result')
mars.nasa <- mars[c(1:4, 9, 10, 12:14, 16, 17, 19:22), 1:4]  # extract NASA events
 
time.launch <- mars.nasa[, c(1,2,4)]
colnames(time.launch) <- c('id', 'Date', 'Type')
time.launch$Annot <- paste(time.launch$id, " launched on ", time.launch$time, sep = "")
time.arrive <- mars.nasa[, c(1,3,4)]
colnames(time.arrive) <- c('id', 'Date', 'Type')
time.arrive$Annot <- paste(time.arrive$id, " arrived on ", time.arrive$time, sep = "")
time.mars <- rbind(time.launch, time.arrive)
 
for(i in 1:12) {
  time.mars$Date <- gsub(month.name[i], i, time.mars$Date)
}
time.mars$Date <- as.Date(time.mars$Date, '%d %m %Y')
 
dat.mars <- time.mars[, 2:4]
dat.mars$id <- "2007 Constant"
dat.mars$Budget <- NA  # events data is ready
# generate the chart
dat <- rbind(dat, dat.mars)
dat[141:143, 'id'] <- 'Nominal'
dat[141:143, 'Budget'] <- 17711
dat[141:143, 'Date'] <- as.Date(paste(c(2013, 2016, 2018), "-1-1", sep = ""))
dat[141:143, 'Type'] <- c('Orbiter', rep('Lander', 2))
dat[141, 'Annot'] <- 'MAVEN will investigate Mars\' atmosphere history'
dat[142, 'Annot'] <- 'Insight will compete with two other concepts in the Discovery program'
dat[143, 'Annot'] <- 'Red Dragon will look for biosignatures'
 
library(googleVis)
dat.timeline <- gvisAnnotatedTimeLine(dat, datevar = 'Date', numvar = 'Budget', 
			          idvar = 'id', titlevar = 'Type', annotationvar = 'Annot',
				 options = list(displayAnnotations = T, 
				                displayExactValues = T,
					       allValuesSuffix = ' million dollars',
					       dateFormat = 'yyyy',
					       thickness = 2,
					       width = 1000, height = 400))
plot(dat.timeline)