# Rework of the blood pressure stats
# Author: Rainer Koenig

library(ggplot2) # for the graphical output 
library(reshape) # for the melt function call

# extract the last num lines from the dataset
get_latest <- function(data, num) {
  rows <- nrow(data)
  cols <- ncol(data)
  start <- rows - num +1;
  return( data[start:rows,0:cols] )
}

# read the bloodpressure data from the file
bp_data <- read.table("daten.txt", header=TRUE, sep=" ")
bp_data$Timestamp <- strptime(paste(bp_data$Datum, bp_data$Zeit), "%d.%m.%y %H:%M")
bp_data <- subset(bp_data, select=c(-Datum, -Zeit))

# get a selection of the latest 60 measures
bp_latest <- get_latest(bp_data, 60)

# transform the data to a long table
bp_plotdata <- melt(bp_latest, id="Timestamp")

plot_latest_lines <- ggplot(bp_plotdata, aes(x=Timestamp, y=value, colour=variable)) + geom_line() +
      geom_point() + ylab("Messwert") + xlab("Datum") + scale_colour_discrete(name="Messwert") +
      scale_y_continuous(breaks=seq(40,200,by=10)) + labs(title="Bludruck (letzte 60 Werte)")

plot_scatter_all <- ggplot(bp_data, aes(x=Sys, y=Dia)) + geom_point(alpha=0.2) +
      stat_smooth(method=lm) + labs(title="Korrelation Sys/Dia Werte")

plot_histogram_latest <- ggplot(bp_plotdata, aes(x=value)) + 
  geom_histogram(fill="white", colour="black", binwidth=10) +
  facet_grid(variable ~ .) +
  xlab("Wert") + ylab("Anzahl") + labs(title="Histogramm der letzten 60 Messungen")