{"id":298,"date":"2019-06-16T14:14:09","date_gmt":"2019-06-16T18:14:09","guid":{"rendered":"http:\/\/bhoey.com\/blog\/?p=298"},"modified":"2020-06-24T14:49:35","modified_gmt":"2020-06-24T18:49:35","slug":"simple-time-series-graphs-with-gnuplot","status":"publish","type":"post","link":"https:\/\/bhoey.com\/blog\/simple-time-series-graphs-with-gnuplot\/","title":{"rendered":"Simple Time Series Graphs With Gnuplot"},"content":{"rendered":"

Introduction<\/h3>\n

Gnuplot<\/a> is a feature rich command-line graphing utility available for Windows, Linux and Mac OSX. Though capable of generating much more advanced formula-based plots its also very handy at producing quick, ad-hoc time series graphs.<\/p>\n

The Test Dataset<\/h3>\n

For our example we'll use the following basic dataset saved to file 'mydata.txt'<\/p>\n

2019-02-01  15\n2019-03-01   8\n2019-04-01  16\n2019-05-01  20\n2019-06-01  14\n<\/pre>\n
Gnuplot Commands<\/h3>\n
These commands were tested with gnuplot 5.0 patchlevel 5<\/p>\n
set xdata time                           # Indicate that x-axis values are time values\nset timefmt \"%Y-%m-%d\"                   # Indicate the pattern the time values will be in\nset format x \"%m\/%y\"                     # Set how the dates will be displayed on the plot\n\nset xrange [\"2019-01-01\":\"2019-12-31\"]   # Set x-axis range of values\nset yrange [0:30]                        # Set y-axis range of values\n\nset key off                              # Turn off graph legend\nset xtics rotate by -45                  # Rotate dates on x-axis 45deg for cleaner display\nset title 'Squirrels Spotted'            # Set graph title\n\nset terminal jpeg                        # Set the output format to jpeg\nset output 'output.jpg'                  # Set output file to output.jpg\n\nplot 'mydata.txt' using 1:2 with linespoints linetype 6 linewidth 2\n\n<\/pre>\n
Running Gnuplot<\/h3>\n
Although you can paste the commands above right into gnuplot, it usually makes sense to put these commands in their own file for future reuse and reference. If we put these into the file 'gpcommands.txt' then we just need to run:<\/p>\n
$ gnuplot < gpcommands.txt\n<\/pre>\n
To have it generate the following plot:<\/p>\n\n\n
\"time<\/figure>\n\n\n
Bonus Example: Multiple Series<\/h3>\n
The above is a good demonstration of how to create a minimal time series graph, however often you'll want to chart multiple series together. Lets adjust our source data file to add two more series (as represented by columns) and one more row as we'll be widening the dimensions later:<\/p>\n
2019-02-01  10  8  12\n2019-03-01   8  9  12\n2019-04-01   9  10 10\n2019-05-01  11  10 11\n2019-06-01  14  9  11\n2019-07-01  14  10 12\n<\/pre>\n
For the gnuplot commands we'll add a bit of polish:<\/p>\n