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yudhastyawan/headersac.csv

Created April 21, 2021 19:43
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SAC Tutorial and Case Study
Raw
headersac.csv
We can make this file beautiful and searchable if this error is corrected: No commas found in this CSV file in line 0.
Word Type NAMES o o o o
0 F DELTA DEPMIN DEPMAX SCALE ODELTA
5 F B E O A INTERNAL
10 F T0 T1 T2 T3 T4
15 F T5 T6 T7 T8 T9
20 F F RESP0 RESP1 RESP2 RESP3
25 F RESP4 RESP5 RESP6 RESP7 RESP8
30 F RESP9 STLA STLO STEL STDP
35 F EVLA EVLO EVEL EVDP MAG
40 F USER0 USER1 USER2 USER3 USER4
45 F USER5 USER6 USER7 USER8 USER9
50 F DIST AZ BAZ GCARC INTERNAL
55 F INTERNAL DEPMEN CMPAZ CMPINC XMINIMUM
60 F XMAXIMUM YMINIMUM YMAXIMUM UNUSED UNUSED
65 F UNUSED UNUSED UNUSED UNUSED UNUSED
70 I NZYEAR NZJDAY NZHOUR NZMIN NZSEC
75 I NZMSEC NVHDR NORID NEVID NPTS
80 I INTERNAL NWFID NXSIZE NYSIZE UNUSED
85 I IFTYPE IDEP IZTYPE UNUSED IINST
90 I ISTREG IEVREG IEVTYP IQUAL ISYNTH
95 I IMAGTYP IMAGSRC UNUSED UNUSED UNUSED
100 I UNUSED UNUSED UNUSED UNUSED UNUSED
105 L LEVEN LPSPOL LOVROK LCALDA UNUSED
110 K KSTNM KEVNM* NaN NaN NaN
116 K KHOLE KO KA NaN NaN
122 K KT0 KT1 KT2 NaN NaN
128 K KT3 KT4 KT5 NaN NaN
134 K KT6 KT7 KT8 NaN NaN
140 K KT9 KF KUSER0 NaN NaN
146 K KUSER1 KUSER2 KCMPNM NaN NaN
152 K KNETWK KDATRD KINST NaN NaN
Raw
readbinarysac.py
# import os, struct, numpy and matplotlib
import os
import struct
import numpy as np
import matplotlib.pyplot as plt
# identify header sac filename and a sac binary filename
headerfile = "headersac.csv"
filename = "example.sac"
# read header sac filename and change to the list python
file = open(headerfile,'r')
hdr = file.readlines()
for i in range(len(hdr)):
hdr[i] = hdr[i].split()
file.close()
# clustering and making the categories the header type
# hdrVar as a list of SAC header type items
# spec as a list of struct type corresponded and length of characters
hdrVar = []
spec = []
for i in range(len(hdr)):
for j in range(len(hdr[0])):
if i != 0:
if j != 0 and j != 1:
if hdr[i][j] != 'NaN':
hdrVar.append(hdr[i][j])
if hdr[i][1] == 'F':
spec.append(['f',4])
if hdr[i][1] == 'I':
spec.append(['i',4])
if hdr[i][1] == 'L':
spec.append(['?',4])
if hdr[i][1] == 'K' and hdr[i][j] != 'KEVNM*':
spec.append(['s',8])
if hdr[i][1] == 'K' and hdr[i][j] == 'KEVNM*':
spec.append(['s', 16])
# opening the sac binary file and storing the length to variable 'size'
f = open(filename, 'rb')
f.seek(0, os.SEEK_END)
size = f.tell()
print('size of the data is ',size)
# opening again and converting binary to format characters
# bi variable as a control of what the length that has been read
# amp variable as a list of amplitude data
# the list of SAC headers only display in the command/output window
# except DELTA due to plotting
f = open(filename,'rb')
bi = 0
amp = []
DELTA = 0
while bi < size:
if bi < len(hdrVar):
for i in range(len(hdrVar)):
if spec[i][0] != 's' and spec[i][0] != '?':
datBin = f.read(spec[i][1])
print(hdrVar[i], struct.unpack('<{}'.format(spec[i][0]),datBin)[0])
if hdrVar[i] == 'DELTA':
DELTA = struct.unpack('<{}'.format(spec[i][0]),datBin)[0]
bi += spec[i][1]
elif spec[i][0] == '?':
datBin = f.read(spec[i][1])
print(hdrVar[i], struct.unpack('<{}'.format(spec[i][0]), datBin[:1])[0])
bi += spec[i][1]
else:
datBin = f.read(spec[i][1])
print(hdrVar[i], str(struct.unpack('<{}{}'.format(spec[i][1],spec[i][0]), datBin)[0]).split("'")[1])
bi += spec[i][1]
else:
datBin = f.read(4)
amp.append(struct.unpack('<f', datBin))
bi += 4
# plot the data
# t as the time
t = np.r_[0:len(amp)*DELTA:DELTA]
plt.plot(t,amp)
plt.ticklabel_format(style='sci', axis='y', scilimits=(0,0))
plt.title('Example of plot data')
plt.ylabel('Amplitude')
plt.xlabel('Time (s)')
plt.show()
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