Dongsh

python obspy read sac file with header

库依赖

• obspy
• matplotlib.pyplot * opition

以 Stream 对象读取SAC文件

Use obspy.read('fileName') to read file to a stream object.

Stream means that a sac file contain one or more trace data info, hence index can be used to localize different trace in a stream.

Easily, It’s a fast way to check how many trace in the sac stream:

>>> print(sac)
1 Trace(s) in Stream:
.GRN21..N | 1969-12-31T23:59:59.900000Z - 1970-01-01T00:00:02.450000Z | 100.0 Hz, 256 samples

Object

To call the data, index format as sac[0] can be applied to the stream. then use . operator to call the subject as sac[0].data, which will return the raw data object of the first trace in the sac file.

The method to call the header of sac can be sac[0].stats.sac.headerObj.

Both the data and header can be edited or changed directly.

Easy Plot

For each trace, a easy way to Plot is provided by obspy:

sac[0].plot()

Demonstration code

import obspy as obs

sacA = obs.read('CPS0001n.sac')
sacB = obs.read('CPS0002n.sac')

dataA = sacA[0].data
dataB = sacB[0].data
dataOutput = dataA - dataB

distA = sacA[0].stats.sac.dist
distB = sacB[0].stats.sac.dist
distOut = (distA + distB) / 2

sacOut = sacA
sacOut[0].data = dataOutput
sacOut[0].stats.sac.dist = distOut

sacOut.write('out.sac',formta='SAC')

# verification

sac = obs.read('out.sac')
sac[0].plot()