Waveform Plotting Tutorial

Read the files as shown in ObspyTutorial. We will create and use two different obspy.Stream objects throughout this tutorial. The first one, singlechannel, just contains one continuous Trace and the other one, threechannel, contains three channels of a seismograph.

>>> from obspy.core import read
>>> singlechannel = read('COP.BHE.DK.2009.050')
>>> print singlechannel
1 Trace(s) in Stream:
DK.COP..BHE | 2009-02-19T00:00:00.035100Z - 2009-02-19T23:59:59.985100Z | 20.0 Hz, 1728000 samples
>>> threechannels = read('COP.BHE.DK.2009.050')
>>> threechannels += read('COP.BHN.DK.2009.050')
>>> threechannels += read('COP.BHN.DK.2009.050')
>>> print threechannels
3 Trace(s) in Stream:
DK.COP..BHE | 2009-02-19T00:00:00.035100Z - 2009-02-19T23:59:59.985100Z | 20.0 Hz, 1728000 samples
DK.COP..BHN | 2009-02-19T00:00:00.025100Z - 2009-02-19T23:59:59.975100Z | 20.0 Hz, 1728000 samples
DK.COP..BHZ | 2009-02-19T00:00:00.025100Z - 2009-02-19T23:59:59.975100Z | 20.0 Hz, 1728000 samples

Simple plotting

Using the plot method of the Stream objects will show the plot. The default size of the plots is 800x250 px. Use the size attribute to adjust it to your needs.

>>> singlechannel.plot()

Save the plot

To save a file use the outfile parameter. The format is determined automatically from the filename. This example also shows the options to adjust the color of the graph, the number of ticks shown, their format and rotation and how to set the start- and endtime of the plot.

>>> singlechannel.plot(outfile = 'singlechannel_adjusted.png', color = 'red', number_of_ticks = 7,
... tick_rotation = 5, tick_format = '%I:%M %p', starttime = singlechannel[0].stats.starttime + 60*60,
... endtime = singlechannel[0].stats.starttime + 60*60 + 120)

Plotting multiple channels

If the Stream object contains more than one Trace, each Trace will be plotted in a subplot. The start- and endtime of each Trace will be the same and the range on the y-axis will also be identical on each trace. Each additional subplot will add 250 px to the height of the resulting plot. Use the size attribute to change the size of the plot.

>>> threechannels.plot()

Options

Various options are available to change the appearance of the waveform:

• outfile: Output file string. Also used to automatically determine the output format. Currently supported is emf, eps, pdf, png, ps, raw, rgba, svg and svgz output. Defaults to None.
• format: Format of the graph picture. If no format is given, the outfile parameter will be used to try to automatically determine the output format. If no format is found, it defaults to png output. If no outfile is specified but a format is, then a binary imagestring will be returned. Defaults to None.
• size: Size tupel in pixel for the output file. This corresponds to the resolution of the graph for vector formats. Defaults to 800x250 px.
• starttime: Starttime of the graph as a datetime object. If not set, the graph will be plotted from the beginning. Defaults to False.
• endtime: Endtime of the graph as a datetime object. If not set, the graph will be plotted until the end. Defaults to False.
• dpi: Dots per inch of the output file. This also affects the size of most elements in the graph (text, linewidth, ...). Defaults to 100.
• color: Color of the graph. Defaults to 'k' (black).
• bgcolor: Background color of the graph. Defaults to 'w' (white).
• transparent: Make all backgrounds transparent (True or False). This will overwrite the bgcolor parameter. Defaults to False.
• minmaxlist: A list containing minimum, maximum and timestamp values. If none is supplied, it will be created automatically. Useful for caching. Defaults to False.
• number_of_ticks: Number of the ticks on the time scale to display. Defaults to 5.
• tick_format: Format of the time ticks according to strftime methods. Defaults to '%H:%M:%S'.
• tick_rotation: Number of degrees of rotation for ticks on the time axis. Ticks with big rotations might be cut off depending on the tick_format. Defaults to 0.

Color Options

Colors can be specified as defined in the  matplotlib documentation.

Short Version: For all color values, you can use legit html names, html hex strings (e.g. '#eeefff') or you can pass an R , G , B tuple, where each of R , G , B are in the range [0,1]. You can also use single letters for basic built-in colors ('b' = blue, 'g' = green, 'r' = red, 'c' = cyan, 'm' = magenta, 'y' = yellow, 'k' = black, 'w' = white) and gray shades can be given as a string encoding a float in the 0-1 range.