Processing RAW data to make a web displayable graph

Question

I have data on a Linux system, about 44K data points, that I'd like to make a Scatter plot. The plot should be saved so that it can be displayed on a website (JPG?).

Some other parameters:

X-Axis: one day per tick, max 31 days total

Y-Axis: Integer Number 0-100, tick marks every 10

Scatter plot…..DO NOT draw lines between points.

Each data point looks like:

10/20/2010 23:45:22,57

Would like to include labels for X, Y axis

Would like to include a title

Would like the days to come out as either 10/20 under each X-tick point, or just simply the day number

Any ideas as to what program(s) I should consider....hopefully free. I have a choice of Linux operating systems, Centos 5.5, Fedora 13, Suse 11 SP1.

Thanks for your help and consideration.

Answer 1

gnuplot should handle your needs. It can render to various canvases such as PNG and SVG.

Answer 2

R with Hadley Wickham's excellent ggplot2 library. The built in graphing library is completely adequate, but ggplot2 has beautiful, sane defaults.

after R is installed to install ggplot2: install.packages("ggplot2")

Assuming your data has the form:

date_time,value
10/20/2010 23:45:22,57
10/30/2010 23:45:22,102

Your whole script in R would look something like:

mydata <- read.csv("path/to/csv/data.csv", sep=",", 
    header = TRUE, stringsAsFactors = FALSE)
mydata$date_time <- as.POSIXct(
     strptime(mydata$date_time, "%m/%d/%Y %H:%M:%S")) #turns your dates 
                                                      #into POSIX time objects
head(mydata)                                          #just see that it looks good 
library(ggplot2)
p <- ggplot(mydata, aes(date_time, value))         #make a ggplot2 plot object
p + geom_point() + ylab('Y label goes here') +     #add points, ylabel, xlabel and a title
    xlab("Date") + opts(title = "Snappy Title goes here")

Here's one I made while answering this questing using the USGS hydrograph data for the Elwha