Thread: PySAC

Hi Norman,

I have read that there exists a set of Python functions which allow
easy access to SAC files. After some extensive googling I have been
unable to locate anything other than a mention in the following
article: http://adsabs.harvard.edu/abs/2004AGUFM.S21A0273H

Can someone please point me in the correct direction so that I don't
spend time duplicating code?

I also stumbled over that article and couldn't find any other mention of this
code, that's why I wrote my own module: here it is. It's not very sophisticated
and also not much tested so far, so be prepared for surprises. It can only do IO
on binary SAC files.

Usage is like this:

import pysacio

Read a SAC file:

sac = pysacio.SacFile('test.sac')

Access header values (assignment is also fine):

sac.delta

0.5

Access the data: it is returned as a NumPy array:

sac.data[0]

array([ 0., 0., 1., 2., 0.], dtype=float32)

To simplify dealing with the reference time of the SAC file, I implemented this:

sac.get_ref_time()

Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/bonus/lib/python2.4/site-packages/pysacio.py", line 64, in get_ref_time
raise SacError('Not all header values for reference time are set.')
pysacio.SacError: Not all header values for reference time are set.


... aaah, OK, the time headers were not set in this file, so let's set them to
the current system time, for the demo:

import time
sac.set_ref_time(time.time())
sac.get_ref_time()

1250703611.993

sac.nzyear

2009

sac.nzjday

231

sac.nzhour

17

You can 'print' the SAC object:

print sac

delta: 0.5
b: 0.0
e: 2.0
nzyear: 2009
nzjday: 231
nzhour: 17
nzmin: 40
nzsec: 11
nzmsec: 993
nvhdr: 6
npts: 5
iftype: 1
leven: 1
lpspol: 0
lovrok: 1
lcalda: 1
unused17: 0
kevnm: -12345 -12345


And to write it to file:

sac.write('newfile.sac')

Happy coding!

Sebastian