SourceSpec Changelogο
Earthquake source parameters from P- or S-wave displacement spectra
Copyright (c) 2011-2024 Claudio Satriano satriano@ipgp.fr
v1.8 - 2024-04-07ο
This long overdue release brings many improvements, new features and bugfixes gradually introduced during the last year.
Release highlights:
New file formats for events and spectra
New configuration options to better specifify velocity and density models
Better support for P-wave inversion and teleseismic events
Support for radiation pattern correction from focal mechanism
Option for travel time-based signal window length
More options to control the calculation of source radius and stress drop
Improved estimation of radiated energy
New source parameter: apparent stress
Fix for map tiles not plotted anymore
This release requires at least Python 3.7.
Warning: the SQLite database used by this version is not compatible with
previous versions. You will need to upgrade your old database manually or using
source_spec -u DATABASE_FILE_NAME
.
Make sure to read the detailed Changelog below π
Input/outputο
Introducing a new file format for providing event information (hypocentral location, magnitude, focal mechanism, moment tensor): the SourceSpec Event File.
New HDF5 and TEXT file formats to store spectra
Station residuals are now saved in an HDF5 spectrum file, instead of a pickle file
New config file option
save_spectra
to save the spectra to an HDF5 file in the output directoryChanges in the YAML output file:
bsd
(Brune stress drop) parameter renamed tossd
(static stress drop)Store in the
event_info
section the values of vp, vs and rho close to the hypocenterStore in the
inversion_info
section the type of wave used for the inversion (P, S, SV or SH)
Changes in the SQLite database (warning: these changes break compatibility with previous database versions):
bsd
(Brune stress drop) parameter renamed tossd
(static stress drop)Store the
Stations
table information on whether each parameter is an outlier (see #38)Make place in the
Stations
table for station-level errors on radiated energy (even if they are currently not computed)Store in the
Events
table the number of observations used for computing each summary parameterStore in the
Events
table weighted means for radiated energy and local magnitude, even if those means are currently the same as the simple means, since those parameters do not have station-level errors definedNew columns for apparent stress in both
Events
andStations
tablesStore in the
Events
table the values of vp, vs and rho close to the hypocenterStore in the
Events
table the type of wave used for the inversion (P, S, SV or SH)
New command line option (
-u
or--updatedb
) to update an existing database from a previous versionInput files are now linked symbolically in the
input_files
subdirectory of the output directory (not implemented for Windows)New command line option (
-R
or--run_id_subdir
) to userun_id
(if defined) as a subdirectory of the event directoryPrint event info to console and to log file
HTML report improvements:
Event name in the summary table, if available
Author, agency and run completion date in the summary table
SourceSpec version in the inversion information table
Link to input files
Information on the type of wave used for the inversion (P, S, SV or SH)
Processingο
Use all the available components to compute P-wave spectra (previously, only the vertical component was used)
Possibility of specifying a free surface amplification factor different from 2
Possibility of specifying a layered velocity and density model for the source
Possibility of specifying a different density for the source and for the stations
If density is not provided (i.e., it is
None
), use the density from the global velocity model βiasp91βTeleseismic geometrical spreading model (Okal, 1992)
New weighting option based on inverse frequency, so that lower frequencies have larger weight in the inversion. If traces contain noise, weights will be set to zero where SNR < 3 (see #37)
For weights computed from spectral S/N ratio (noise weighting), set to zero all the weights below 20% of the maximum weight, so that these weakly constrained parts of the spectrum are ignored in the inversion
Possibility of using variable signal window lengths for each station as a function of the travel time of the P or S wave (see #48)
Inversionο
Possibility of using the magnitude (or scalar moment) provided in the event file as initial Mw value for the inversion
Reintroduced the possibility of providing the variability around the initial Mw value
By combining the previous options, it is now possible to fix the Mw value during the inversion to the value provided in the event file
Post-Inversionο
Possibility of choosing the βkβ coefficient to compute source radius from corner frequency (Kaneko and Shearer, 2014)
Better control on the frequency range used for computing radiated energy (see #49)
Use station-specific radiation pattern (when available) for computing radiated energy
Take into account for energy partition when computing radiated energy (Boatwright and Choy, 1986). This affects mostly the radiated energy computed from P waves
New source parameter: apparent stress
For parameters with no station-level uncertainty defined (currently, radiated energy and local magnitude), use simple mean when computing summary weighted averages (the previous behavior was to not compute weighted averages for these parameters)
Plottingο
Show the station radiated energy (Er) value on the station spectra plots
Show the summary radiated energy (Er) value on the stacked spectra plot
Station maps improvements:
Possibility of choosing a basemap style or no basemap
Possibility of not plotting the coastlines
Exclude outliers when computing colorbar limits
Improved computation of bounding box for regional and teleseismic events
Use a global orthographic projection when using stations at large teleseismic epicentral distances (more than 3000 km)
Changes to
plot_sourcepars
:Read vp, vs and rho from the SQLite database (previously: vs was hardcoded to 3.5 km/s, rho to 2700 kg/m3 and vp was not used)
Read the source radius βkβ coefficient from the SQLite database (previously: βkβ was hardcoded to 0.3724, value for the Brune model)
New command line option
--wave_type
to select the wave type (P, S, SV or SH) for plots involving the corner frequencyPossibility of plotting histogram of apparent stress
Option to filter events by apparent stress
Config fileο
New config parameter
epi_dist_ranges
to select stations within one or more ranges of epicentral distances. It replaces the old parametermax_epi_dist
.New config parameter
free_surface_amplification
to specify the free surface amplification factor (default: 2)New config parameter
layer_top_depths
to specify the depth of the top of the layers in a layered velocity and density modelThe config parameters
vp_source
,vs_source
andrho_source
can now be lists of values, to specify a layered velocity and density model for the sourceConfig parameter
rho
renamed torho_source
New config parameter
rho_stations
New config parameter
geom_spread_min_teleseismic_distance
to set the minimum epicentral distance for using the teleseismic geometrical spreading modelNew config parameters
kp
andks
to set the βkβ coefficient for computing source radius from corner frequencyConfig parameter
pi_bsd_min_max
renamed topi_ssd_min_max
New option
inv_frequency
for the config parameterweighting
(see #37)Config parameter
max_freq_Er
replaced byEr_freq_range
(see #49)New parameters,
qml_event_description
andqml_event_description_regex
, to obtain the event name from the QuakeML event βdescriptionβ tagNew parameter
Mw_0_from_event_file
to use the magnitude (or scalar moment) provided in the event file as initial Mw value for the inversionReintroduced the parameter
Mw_0_variability
to set the variability around the initial Mw valueNew parameter
plot_save_asap
to save plots as soon as they are ready. This uses less memory but slows down the code.New parameter
plot_map_style
to choose the map styleNew parameter
plot_map_api_key
to provide a Stadia Maps api key for Stamen Terrain basemapNew option for the parameter
plot_coastline_resolution
:no_coastline
New config parameter
variable_win_length_factor
to specify window length as a fraction of the travel time of the P/S wave (see #48)
Bugfixesο
Fix source radius computation when using P waves (use P-wave velocity instead of S-wave velocity)
Do not ignore picks labeled with lowercase βpβ or βsβ
Fixed: config parameter
p_arrival_tolerance
was used also for S waves, instead ofs_arrival_tolerance
(see #35)Fix Boatwright spreading model (log10 instead of natural log)
Fix bug where signal and noise windows were plotted with the wrong length, under certain circumstances (see #35)
Fixes related to records with short signal windows (see #39)
Fix for beachball not plotted anymore with recent versions of Matplotlib.
Fix bug where traces ignored because of low spectral S/N ratio, where still plotted as if they were valid traces
Fix bug when specifying an absolute path for output directory: the path was treated as relative (see #40)
Fix bug where paths starting with tilde (~) were not parsed correctly (see #43 and #44)
Fix bug where local magnitude was not written to the HYPO71 output file, when using weighted mean as reference statistics
Fix for Stamen Terrain basemap now requiring an API key from Stadia Maps
Requirementsο
Python minimum version raised to 3.7
Matplotlib minimum version raised to 3.2
Cartopy minimum version raised to 0.21
v1.7 - 2023-03-31ο
This release improves trace processing through the use of modern routines for instrument correction, optional baseline removal, a new clipping detection algorithm and a better definition of signal and noise time windows.
A new plot is introduced, βstacked spectraβ which allows to compare all the
spectra at once (and easily detect problematic stations π).
Also, a new command line tool, plot_sourcepars
, allows making aggregate
plots of source parameters for many events (starting from the SQLite database).
New config file parameters have been added, while some have been removed.
Please run source_spec -U CONFIG_FILE_NAME
to update your old config file.
As always, many bugfixes and improvements have been made in this release. Thanks to all the users who took time to write and ask questions (by mail or using the official SourceSpec Discussions).
Big kudos to Kris Vanneste @krisvanneste who helped all along the development with code review and testing and submitted pull requests on noise windows and clipping detection.
Below is the detailed Changelog π
v1.7: Input/outputο
Possibility of using a single PAZ file as a βgenericβ PAZ file for all the stations
Command line option
--station_metadata
(or-w
) for overriding the config file parameter with the same name (see pull request #16)Removed command line option
--no-response
for avoiding removing instrument response (use the config optioncorrect_instrumental_response
instead)New output file in YAML format. The old
.out
file is still available but deprecated.Information on the inversion procedure in YAML and HTML output
Option to add an agency logo to the HTML page
Possibility of generating HTML report without figures (see #30)
v1.7: Processingο
Use modern ObsPy
trace.remove_response()
routine for instrument correction (see #27)Option to remove the trace baseline after instrument correction and before filtering (
remove_baseline
config parameter) (see #25)New algorithms for clipping detection based on kernel density estimation of the trace amplitude values (see #23, #24, #25)
Two methods are available:
clipping_score
: compute a trace clipping score based on the shape of the kernel density estimation.clipping_peaks
: check if trace is clipped, based on the number of peaks in the kernel density estimation;
Use
clipping_detection_algorithm
in the config file to choose the algorithm and the otherclipping_*
parameters to adjust the results.The algorithms can also be called from the command line, e.g. for debug purposes, using the shell command
clipping_detection
.
Relax noise window requirements if noise weighting is not used. This is useful for older triggered records with noise windows that are short or even missing entirely (see pull request #18)
Some small improvements were made in the window definitions (see pull request #18):
Generate error if signal window is incomplete (P- or S-arrival before the start time of the trace)
Warn if noise window overlaps with P-window (instead of S-window, as in previous versions)
Constrain
signal_pre_time
for S-phase to half the S-P interval, if this interval is shorter thansignal_pre_time
(i.e., for short-distance records with short S-P interval)
Extract source and station P and S velocities from global βiasp91β velocity model, if both
v(p,s)_source
andv(p,s)_stations
are set toNone
(see #20)Magnitude limits for inversion are now autoset between 90% of the minimum of the spectral plateau and 110% of its maximum (see #22)
v1.7: Post-Inversionο
Possibility of choosing the reference summary statistics that will be used for map plots, QuakeML and HYPO output, as well as for the βEvent Summaryβ section in HTML report and for computing station spectral residuals. Available summary statistics are:
mean
weighted_mean
percentiles (new!)
Possibility of defining the number of sigmas for uncertainties on event means and weighted means
v1.7: Plottingο
New plot: stacked spectra
Do not zero-pad traces to common length when plotting, so that missing data at beginning or at the end can be easily detected (see #21)
Plot noise and signal windows separately for each component (see #21)
Show on the trace plot the reason why a trace has been ignored
Logscale for boxplots, if parameters span a large interval (see pull request #15)
Support for SVG format for plot files (can be used in HTML output as alternative to PNG)
Improved trace plot quality for vector formats (PDF, SVG)
New command line tool:
plot_sourcepars
to make 1D or 2D plot of source parameters from a sqlite parameter file.
v1.7: Config fileο
Removed
sensitivity_only
option fromcorrect_instrumental_response
Removed config parameter:
Mw_0_variability
Removed config parameter:
clip_max_percent
New config parameter:
remove_baseline
New config parameters for clipping detection:
clipping_detection_algorithm
clipping_debug_plot
clipping_score_threshold
clipping_peaks_sensitivity
clipping_peaks_percentile
Config file section
AVERAGES PARAMETERS
renamed toSUMMARY STATISTICS PARAMETERS
New config parameter:
reference_statistics
New config parameter:
n_sigma
New config parameters for percentiles calculation:
lower_percentage
,mid_percentage
andupper_percentage
New config parameters for filtering and spectral windowing of displacement signals:
bp_freqmin_disp
,bp_freqmax_disp
freq1_disp
,freq2_disp
Default values for
t_star_min_max
(instead ofNone
)
v1.7: Code improvementsο
Large refactoring of the whole codebase, to make the code more modern and easier to maintain (see #28)
v1.7: Bugfixesο
Properly ignore vertical components when
ignore_vertical
isTrue
Fix a bug preventing reading phase picks from HYPOINVERSE-2000 files
Fix for noise window not showing up in PNG trace plots in some cases
Fix reading velocities from NLL model (see #20)
HTML report: better scrollbars for station table across all the browsers
Fix for cropped map for very large station-to-event distances (greater than 500 km)
Fix a bug in generating evid form origin time when reading origin time from SAC header and the number of seconds was 59
Fix a crash when no map tiles were available at the selected zoom level
Fix for a corner case where the three components of the same instrument have different trace length (see #31)
Fix
source_residuals
, which didnβt work anymore
v1.6 - 2022-08-02ο
This release introduces several modifications to the config file.
You will need to upgrade your old config files manually or using
source_spec -U CONFIG_FILE_NAME
.
This release requires at least Python 3.6.
A lot of effort has been devoted to improve the documentation. Please check it out on https://sourcespec.readthedocs.io/
v1.6: Input/outputο
QuakeML output (when using QuakeML input)
Command line option
--run-id
to provide a string identifying the current run (see pull request #6)Write SourceSpec version to parfile
Write SourceSpec version and run complete time to SQLite file
Write author and agency info (if specified) to output files, figures and HTML report
HTML page for misfit plots (when using grid search or importance sampling)
Station table in HTML report is now sortable (and its header remains fixed)!
Reduce PNG figures file size, while improving their resolution π
Removed option to read event information and traces from a pickle file (rarely used)
v1.6: Processingο
Support for P-wave spectral inversion (see pull request #9)
It is now possible to provide different vp and vs velocities, close to the source and close to the stations (see the new config options above and issue #5)
Possibility to choose a geometrical spreading model between (see issue #8):
rβΏ (default: n=1 β body waves)
Boatwright et al. (2002): βrβ below a cutoff distance, frequency-dependent above the cutoff distance
Use travel time to compute quality factor from t* (and viceversa) (see issue #5)
Compute travel time from pick and origin time, when possible (see issue #10)
Warn if noise window ends after P or S arrival
v1.6: Post-Inversionο
Subtract the integral of noise spectrum from the integral of signal spectrum when computing radiated energy, under the hypothesis that energy is additive and noise is stationary
v1.6: Config fileο
Config parameter
paz
has been removed and merged intostation_metadata
Config parameters
vp
andvs
have been renamed tovp_source
andvs_source
(see issue #5)New, optional, config parameter
vp_stations
andvs_stations
Config parameter
pre_p_time
andpre_s_time
have been renamed tonoise_pre_time
andsignal_pre_time
, respectively (see pull request #9)Config parameter
rps_from_focal_mechanism
renamed torp_from_focal_mechanism
(see pull request #9)New config parameter:
geom_spread_model
(see issue #8)Config parameters
PLOT_SHOW
,PLOT_SAVE
andPLOT_SAVE_FORMAT
are now lowercase (plot_show
,plot_save
andplot_save_format
)New, optional, general config parameters for specifying author and agency information. This information is written to output files and figures, if specified
New config parameter,
event_url
, to link the event page from the HTML reportRemoved
DEBUG
config parameterParameters from
GENERAL PARAMETERS
section reorganized into a new section calledTRACE AND METADATA PARAMETERS
Some parameters from
INVERSION PARAMETERS
moved into a new section calledSPECTRAL MODEL PARAMETERS
v1.6: Bugfixesο
Fix for not working
weighting
options:frequency
andno_weight
Fix for negative weights occasionally generated by interpolation
Fix bug when event coordinates are written into sqlite as binary blobs
v1.5 - 2022-05-22ο
This is a pretty big release coming after several months of work on a large dataset of more than 5000 events in Mayotte.
Please read through the changelog to discover all the improvements and new features.
You will need to update your old config files via
source_spec -U CONFIG_FILE_NAME
Note that v1.5 is no more compatible with Python 2!
v1.5: Input/outputο
Write output files into a subdirectory of OUTDIR, whose name is the event id
Support for HYPOINVERSE-2000 output files
Removed autodetection of hypo71 file paths (specific to CRL case)
SQLite output: added radiated energy, weighted averages, errors on parameters, number of observations, hypocentral location and origin time
Removed
-C
argument to apply station correction to spectra. Now spectra are automatically corrected ifresiduals_filepath
is specified in the configuration fileSave an additional event parameter to output files: average quality factor
Save additional station parameters to output files: source radius, Brune stress drop, source radius, quality factor
Mark outliers in
.out
file and in html reportColored console output for log messages! (Not supported on Windows)
v1.5: Processingο
New parameter for setting the width of the spectral smoothing window in terms of frequency decades:
spectral_smooth_width_decades
(see issue #2)Compute spectral weights after spectral correction (when a station residuals file is specified via
residuals_filepath
)Removed configuration parameter
trace_format
New configuration parameter
sensitivity
to provide a constant sensor sensitivity (flat response curve), which overrides any response curve provided in metadataNew parameter for manually specifying trace units:
trace_units
(defaults toauto
)New approach for trace clipping detection (requires just one configuration parameter, named
clip_max_percent
)Check for trace clipping only in the processing window
Use histogram of samples to detect clipping
Fix for wrong component used for βSVβ spectra (see issue #3)
v1.5: Inversionο
New config option:
Mw_0_variability
. Allowed variability aroundMw_0
during the main inversion. Previously hardcoded to 0.1New inversion methods for grid sampling:
grid search (very slow!)
importance sampling of the misfit grid using k-d tree (faster, but less accurate)
Fix for Basin-hopping algorithm not running
v1.5: Post-Inversionο
New set of post-inversion parameters to reject certain inversion results, per-station:
pi_fc_min_max
,pi_t_star_min_max
,pi_bsd_min_max
,pi_misfit_max
Reject inversion results when inverted
fc
is within 10% offc_min
orfc_max
Fix: use logarithmic error width for weighted logarithmic averages
previous way of computing weighted logarithmic averages was not correct!
Option to reject outliers using the IQR (interquartile range) method: parameter
nIQR
Support for non symmetric error on station spectral parameters
Compute additional, per-station parameters: source radius, Brune stress drop and quality factor
Compute errors for all station parameters
Compute weighted averages for all event parameters (except radiated energy)
Compute spectral residuals using weighted average spectral parameters
v1.5: Plottingο
Source parameter box plots to evaluate parameter dispersion across stations and visually detect outliers
Misfit plot (2D and 1D) when using grid sampling
cartopy
removed as installation dependency, since it is not easily installable viapip
Use GSHHS database to draw coastlines.
New config option:
plot_coastline_resolution
Correctly show circles on maps with diagonal smaller than 1 km
Fix plotting map colorbar on Matplotlib 3.5
Make average and errorbar lines more visible on map colorbar
Fix for error on plotting fc map, when only one station is available
Fix trace plot scaling for traces with larger signal outside the plot window
Do not plot βHβ spectrum if there is only one instrument component (since it will coincide with the only component)
Plot uncorrected spectrum when station correction is used
v1.4 - 2021-10-13ο
New config option
rps_from_focal_mechanism
to compute station-specific S-wave radiation pattern from focal mechanism, if a focal mechanism is available in the QuakeML filePlot the focal mechanism on maps, if it is available
Change default inversion algorithm to TNC (truncated Newton algorithm)
Config option
dataless
renamed tostation_metadata
Config option
traceids
renamed totraceid_mapping_file
Config options
ignore_stations
anduse_stations
renamed toignore_traceids
anduse_traceids
, respectivelySupport for 2D NonLinLoc grids (via
nllgrid >= 1.4.1
)Possibility of using a generic
DEFAULT
NonLinLoc time gridAdded
cartopy
as an installation dependencyFixed:
nllgrid
was always requested at runtimeFixed: gracefully handle the case when there is no internet connection and map tiles cannot be downloaded
Fixed (Windows): suppress colored terminal output, which is not supported
Fixed (Windows): it is now possible to relaunch the same run, without having to delete the output directory first
Fixed (Windows): use same timezone names than Linux and macOS
v1.3.1 - 2021-09-13ο
Fix for HTML report not showing trace and spectral plots
HTML report: add Corner Frequency in Event Summary
v1.3 - 2021-08-20ο
HTML reports
Option to provide station-specific spectral windowing
v1.2 - 2021-05-20ο
Use
python-versioneer
to manage version numbers
v1.1 - 2021-04-07ο
Bug fixes:
Accept band code
C
for broadband seismometers sampled at >=250 HzRequire
cartopy>=0.18
for compatibility withmatplotlib>=3.3
v1.0 - 2021-03-03ο
Simplification of time window parameters:
an unique window length,
win_length
, is used for time-domain S/N ratio calculation and spectral analysisthe old parameters,
noise_win_length
ands_win_length
, are no more supported and generate an error
Reorganized config file and improved inline documentation within the file
removed unused option:
fc_0
removed
pre_filt
optionpost-processing check on
fc
bounds has been removed
Option to specify non standard instrument codes (e.g.,
L
for acceleration)Option to specify filter frequencies for local magnitude computation
Plotting improvements:
Show S/N ratio on trace plots
Show spectral S/N ratio on spectrum plots
Option to show/hide ignored traces/spectra (low S/N)
Bug fixes:
Pay attention to location code when building average spectra
Plotting: avoid overlapping traces with different location code
Plotting: avoid overlapping spectra with different location code
v0.9 - 2020-04-24ο
Support for QuakeML input and StationXML
Support for Python 3.5
Only compatible with ObsPy >= 1.1.0
Project reorganization:
Project renamed to SourceSpec
ssp_residuals
renamed tosource_residuals
New installable package (e.g., via
pip
)
Spectra are smoothed in log-freq (no more Konno-Ohmachi)
Inversion is performed in a log-freq space
Option to invert for
t_star_0
on the plateau levelTraces are filtered before computing S/N ratio
Trace clipping detection
Traces are always plotted, even if no inversion is performed
Use by default a global model for theoretical travel time calculation
Possibility of using NonLinLoc travel time grids (requires
nllgrid
)New options for P and S arrival time tolerance
New option for maximum epicentral distance for trace processing
Possibility of using a NonLinLoc model grid for obtaining vs at the source and at the receiver (requires
nllgrid
)Use
log10
of weighting function, since the inversion is done in magnitude unitsUse
json
format fortraceid
correction fileSave config file to output dir (only for
source_spec
)Save run completion time into output file
Logarithmic average and logarithmic (asymmetric) error bars for Mo, fc and source radius
Computation of radiated energy
Station-specific filters
New parameters:
gap_max
,overlap_max
Add legend to spectral plots
Add event information, code version and run completion time to plots
Multifigure plotting for traces and spectra (for large number of stations)
New option to plot a station map, color-coded by station magnitude (requires Cartopy)
Refactoring of local magnitude computation code:
Wood-Anderson amplitude is computed from the whole trace converted to W-A and not converting only the min and max peaks (which is the default in ObsPy)
Trace windowing is computed on HF envelopes
New option for custom Ml coefficients
Remove unnecessary Ml options
Code cleaning and optimization:
Switch from
optparse
(deprecated) toargparse
Code style fixes and refactoring
New option to update a config file from previous versions
BUGFIX: Fix a major bug in reading hypo pick file
BUGFIX: Fix for pick file not read in
source_model
v0.8 - 2014-07-11ο
Trace plot showing S and noise time windows
Improved handling of paz files
Per-station Mo on output file
Code cleaning and optimization
v0.7 - 2014-04-07ο
Code reorganization:
inversion code split to its own functions
Option to use bounded inversion
Station residuals, through
ssp_residuals.py
source_model
can now output tables of trade-off between parametersFix in the way noise trace is computed and processed
Documentation!
v0.6 - 2013-06-05ο
Signal to noise weighting
Improved local magnitude computation
New options:
time domain integration
vertical component
Largely improved plotting function
More data formats supported (Antilles, IPOC)
source_model
: a code for plotting theoretical spectraCode refactoring
v0.5 - 2013-02-10ο
Azimuth computation
Construction of an overall database
Local magnitude computation
konnoOhmachiSmoothing
v0.4 - 2012-04-10ο
Logging infrastructure
Code reorganization
v0.3 - 2012-02-10ο
Output is no more printed at screen, but to file
The plots can be saved to a file as well
We differentiate between short periods and broad bands
v0.2 - 2012-02-06ο
Extended and generalized for the CRL application.
v0.1 - 2012-01-17ο
Initial Python port.