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1,2,4Byte Int and IEEE OK

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cultpenguin
2005-05-11 19:35:06 +00:00
parent 23446f6e81
commit bbb2a9e090
2 changed files with 101 additions and 28 deletions
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segypy.py
+93 -22
View File
@@ -76,6 +76,42 @@ SH_def["dtOrig"]= {"pos": 3218,"type":"uint16"}
SH_def["ns"]={"pos": 3220,"type":"uint16"} #; % 3222
SH_def["nsOrig"]={"pos": 3222,"type":"uint16"} #; % 3224
SH_def["DataSampleFormat"]={"pos": 3224,"type":"int16"} #; % 3226
SH_def["DataSampleFormat"]["descr"]={0:{
1: "IBM Float",
2: "32 bit Integer",
3: "16 bit Integer",
8: "8 bit Integer"}}
SH_def["DataSampleFormat"]["descr"][1]={
1: "IBM Float",
2: "32 bit Integer",
3: "16 bit Integer",
5: "IEEE",
8: "8 bit Integer"}
SH_def["DataSampleFormat"]["bps"]={0:{
1: 4,
2: 4,
3: 2,
8: 1}}
SH_def["DataSampleFormat"]["bps"][1]={
1: 4,
2: 4,
3: 2,
5: 4,
8: 1}
SH_def["DataSampleFormat"]["datatype"]={0:{
1: 'ibm',
2: 'l',
3: 'h',
8: 'B'}}
SH_def["DataSampleFormat"]["datatype"][1]={
1: 'ibm',
2: 'l',
3: 'h',
5: 'float',
8: 'B'}
SH_def["EnsembleFold"]={"pos": 3226,"type":"int16"} #;
SH_def["TraceSorting"]={"pos": 3228,"type":"int16"} #; % 3228
SH_def["VerticalSumCode"]={"pos": 3230,"type":"int16"} #; % 3230
@@ -333,6 +369,8 @@ def getSegyTraceHeader(SH,THN='cdp',data='none'):
def getSegyTraceHeader(SH,THN='cdp',data='none'):
"""
getSegyTraceHeader(SH,TraceHeaderName)
"""
bps=getBytePerSample(SH)
if (data=='none'):
@@ -346,7 +384,7 @@ def getSegyTraceHeader(SH,THN='cdp',data='none'):
ntraces=SH["ntraces"]
thv = zeros(ntraces)
for itrace in range(1,ntraces+1,1):
i=itrace
i=itrace
pos=THpos+3600+(SH["ns"]*bps+240)*(itrace-1);
@@ -389,22 +427,23 @@ def readSegy(filename) :
filesize=len(data)
SH=getSegyHeader(filename)
bps=getBytePerSample(SH)
ntraces = (filesize-3600)/(SH['ns']*bps+240)
# ntraces = 100
printverbose("readSegy : Length of data : " + str(filesize),2)
SH["ntraces"]=ntraces;
SH["ntraces"]=ntraces;
ndummy_samples=240/bps
printverbose("readSegy : ndummy_samples="+str(ndummy_samples),6)
printverbose("readSegy : ntraces=" + str(ntraces) + " nsamples="+str(SH['ns']),2)
# GET TRACE
# GET TRACE
index=3600;
nd=(filesize-3600)/bps
@@ -413,22 +452,33 @@ def readSegy(filename) :
printverbose("readSegy : reading segy data",2)
# READ ALL DATA EXCEPT FOR SEGY HEADER
#Data = zeros((SH['ns'],ntraces))
revision=SH["SegyFormatRevisionNumber"]
if (revision==100):
revision=1
dsf=SH["DataSampleFormat"]
DataDescr=SH_def["DataSampleFormat"]["descr"][revision][dsf]
printverbose("readSegy : SEG-Y revision = "+str(revision),1)
printverbose("readSegy : DataSampleFormat="+str(dsf)+"("+DataDescr+")",1)
if (SH["DataSampleFormat"]==1):
printverbose("readSegy : Assuming DSF=1, IBM FLOATS",2)
printverbose("readSegy : THERE IS A BUG SHIFTING THE SEISMOGRAM FOR OBM FLOATS",-1)
Data1 = getValue(data,index,'ibm',endian,nd)
elif (SH["DataSampleFormat"]==2):
elif (SH["DataSampleFormat"]==2):
printverbose("readSegy : Assuming DSF=" + str(SH["DataSampleFormat"]) + ", 32bit INT",2)
Data1 = getValue(data,index,'l',endian,nd)
elif (SH["DataSampleFormat"]==3):
elif (SH["DataSampleFormat"]==3):
printverbose("readSegy : Assuming DSF=" + str(SH["DataSampleFormat"]) + ", 16bit INT",2)
Data1 = getValue(data,index,'h',endian,nd)
elif (SH["DataSampleFormat"]==5):
printverbose("readSegy : Assuming DSF=" + str(SH["DataSampleFormat"]) + ", IEEE",2)
Data1 = getValue(data,index,'float',endian,nd)
elif (SH["DataSampleFormat"]==8):
elif (SH["DataSampleFormat"]==8):
printverbose("readSegy : Assuming DSF=" + str(SH["DataSampleFormat"]) + ", 8bit CHAR",2)
Data1 = getValue(data,index,'B',endian,nd)
else:
@@ -442,8 +492,16 @@ def readSegy(filename) :
printverbose("readSegy : - stripping header dummy data",2)
Data=Data[:,ndummy_samples:(SH['ns']+ndummy_samples)]
printverbose("readSegy : - transposing",2)
Data=transpose(Data)
# SOMEONE NEEDS TO IMPLEMENT A NICER WAY DO DEAL WITH DSF=8
if (SH["DataSampleFormat"]==8):
for i in arange(ntraces):
for j in arange(SH['ns']):
if Data[i][j]>128:
Data[i][j]=Data[i][j]-256
printverbose("readSegy : read data",2)
@@ -456,13 +514,17 @@ def getSegyTrace(SH,itrace):
SegyTraceHeader,SegyTraceData=getSegyTrace(SegyHeader,itrace)
itrace : trace number to read
THIS DEF IS NOT UPDATED. NOT READY TO USE
"""
data = open(SH["filename"]).read()
bps=getBytePerSample(SH)
data = open(SH["filename"]).read()
# GET TRACE HEADER
index=3200+(itrace-1)*(240+SH['ns']*bps)
SegyTraceHeader=[];
#print index
# GET TRACE
index=3200+(itrace-1)*(240+SH['ns']*bps)+240
SegyTraceData = getValue(data,index,'float',endian,SH['ns'])
@@ -483,19 +545,13 @@ def getSegyHeader(filename):
txt = str(pos) + " " + str(format) + " Reading " + key +"="+str(SegyHeader[key])
printverbose(txt,10)
# SET NUMBER OF BYTES PER DATA SAMPLE
if (SegyHeader['DataSampleFormat']==3):
bps=2
elif (SegyHeader['DataSampleFormat']==8):
bps=1
else:
# SET NUMBER OF BYTES PER DATA SAMPLE
bps=getBytePerSample(SegyHeader)
filesize=len(data)
ntraces = (filesize-3600)/(SegyHeader['ns']*bps+240)
SegyHeader["ntraces"]=ntraces;
@@ -556,7 +612,9 @@ def getValue(data,index,ctype='l',endian='>',number=1):
# Value[i]=0
else:
# ALL OTHER TYPES OF DATA
Value=struct.unpack(cformat, data[index:index_end])
Value=struct.unpack(cformat, data[index:index_end])
if (ctype=='B'):
printverbose('getValue : Ineficient use of 1byte Integer...',-1)
vtxt = 'getValue : '+'start='+str(index)+' size='+str(size)+ ' number='+str(number)+' Value='+str(Value)+' cformat='+str(cformat)
@@ -571,7 +629,7 @@ def print_version():
def print_version():
print 'SegyPY version is ', version
def printverbose(txt,level=1):
if level<=verbose:
print 'SegyPY',version,': ',txt
@@ -601,6 +659,19 @@ def ibm2ieee2(ibm_float):
sign = 1.0
mant= float(a<<16) + float(b<<8) +float(c)
return sign* 16**(istic-64)*(mant/dividend)
def getBytePerSample(SH):
revision=SH["SegyFormatRevisionNumber"]
if (revision==100):
revision=1
dsf=SH["DataSampleFormat"]
bps=SH_def["DataSampleFormat"]["bps"][revision][dsf]
printverbose("getBytePerSample : bps="+str(bps),21);
return bps
##############
testsegy.py
+8 -6
View File
@@ -3,20 +3,22 @@
# testsegy.py
#
import struct
import segypy
filename='mini.sgy'
#filename='mini.sgy'
#filename='lyngbytst1.sgy';
#filename='data_IEEE.segy';
filename='data_IEEE.segy';
filename='data_IBM_REV1.segy';
#filename='data_IBM_REV0.segy';
#filename='data_1byteINT.segy';
#filename='data_2byteINT.segy';
filename='data_IBM_REV0.segy';
filename='data_1byteINT.segy';
filename='data_2byteINT.segy';
#filename='data_4byteINT.segy';
# Set verbose level
segypy.verbose=5;
segypy.verbose=0;
# Read Segy File
Data,SH,STH=segypy.readSegy(filename);