Logging

By default ANUGA prints progress messages to the terminal (stdout). Calling set_logfile() activates file logging: from that point every print() call and every log.*() call is written to both the terminal and the named log file simultaneously.

Quick start

import anuga

anuga.set_logfile('my_run.log')

# All subsequent output goes to terminal AND my_run.log
print('Setting up domain ...')

domain = anuga.rectangular_cross_domain(10, 5)
...

for t in domain.evolve(yieldstep=1.0, finaltime=10.0):
    domain.print_timestepping_statistics()

After this call the file my_run.log contains a complete record of the run including timestep statistics, warnings, and any other printed output.

Output destinations

ANUGA’s output is split into three categories:

Call	Terminal	Log file	When to use
`print(msg)`	✓	✓	User script milestones and results
`log.info(msg)`	✓	✓	Significant simulation events
`log.warning(msg)`	✓	✓	Non-fatal issues that need attention
`log.verbose(msg)`	✗	✓	Internal ANUGA chatter (mesh stats, solver steps)
`log.debug(msg)`	✗	✓	Developer diagnostics

log.verbose() and log.debug() are below the default console threshold (INFO) so they are silently dropped when no log file is active.

Capturing verbose third-party output

Some ANUGA functions (mesh construction, domain distribution) produce detailed print() output when called with verbose=True. Use the file_only() context manager to redirect that output to the log file without showing it on the terminal:

import anuga
import anuga.utilities.log as log

anuga.set_logfile('my_run.log')

with log.file_only():
    domain = anuga.create_domain_from_regions(
        bounding_polygon,
        boundary_tags=tags,
        maximum_triangle_area=res,
        verbose=True,   # full output goes to file, not screen
    )

Outside the with block normal tee behaviour resumes immediately.

Showing verbose output on the terminal

When debugging it can be useful to see all output on the terminal as well. Pass verbose_to_screen=True to set_logfile():

anuga.set_logfile('debug.log', verbose_to_screen=True)

This lowers the console threshold from INFO to DEBUG so log.verbose() and log.debug() messages also appear on screen.

Using log levels directly

The anuga.utilities.log module is available as anuga.log and exposes the standard Python logging levels:

import anuga.utilities.log as log

log.info('Mesh built successfully')
log.warning('Elevation data outside domain extent — using zero')
log.verbose('Triangle count: %d' % n)   # file only
log.debug('CG solver iteration %d, residual %.2e' % (k, r))

Levels in order of decreasing severity:

Level	Constant
`CRITICAL`	`log.CRITICAL` (50) — fatal errors
`ERROR`	`log.ERROR` (40) — recoverable errors
`WARNING`	`log.WARNING` (30) — non-fatal issues
`INFO`	`log.INFO` (20) — normal progress (default console threshold)
`DEBUG` / `VERBOSE`	`log.DEBUG` (10) — detail (default file threshold)