Hi following last week's discussion with Bob Gailer about reading unformatted FORTRAN files, I have attached an example of the file in ASCII format and the equivalent unformatted version. Below is some code that works OK until it gets to a data item that has no additional associated data, then seems to have got 4 bytes ahead of itself. I though I had trapped this but it appears not. I think the issue is asociated with "newline" characters or the unformatted equivalent.
Thanks in advance
Alun Griffiths
==============================
# Test function to write/read from unformatted files
import sys
import struct
# Read file in one go
in_file = open("test.bin","rb")
data = in_file.read()
in_file.close()
# Initialise
nrec = len(data)
stop = 0
items = []
# Read data until EOF encountered
while stop < nrec:
# extract data structure
start, stop = stop, stop + struct.calcsize('4s8si4s8s')
vals = struct.unpack('>4s8si4s8s', data[start:stop])
items.extend(vals)
print stop, vals
# define format of subsequent data
nval = int(vals[2])
if vals[3] == 'INTE':
fmt_string = '>i'
elif vals[3] == 'CHAR':
fmt_string = '>8s'
elif vals[3] == 'LOGI':
fmt_string = '>i'
elif vals[3] == 'REAL':
fmt_string = '>f'
elif vals[3] == 'DOUB':
fmt_string = '>d'
elif vals[3] == 'MESS':
fmt_string = '>%dd' % nval
else:
print "Unknown data type ... exiting"
print items
sys.exit(0)
# extract data
for i in range(0,nval):
start, stop = stop, stop + struct.calcsize(fmt_string)
vals = struct.unpack(fmt_string, data[start:stop])
items.extend(vals)
# trailing spaces
if nval > 0:
start, stop = stop, stop + struct.calcsize('4s')
vals = struct.unpack('4s', data[start:stop])
# All data read so print items
print items
-------------------------------------------------
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'IFLAGS ' 12 'INTE'
-1 2 1 10500 3 10500
2 -1 100 1 105 10500
'QFLAGS ' 10 'LOGI'
F T F F F T F F F F
'NAMES ' 3 'CHAR'
'ORTHO ' 'META ' 'PARA '
'DATABEGI' 0 'MESS'
'TIME ' 1 'REAL'
0.00
'DISTANCE' 10 'DOUB'
0.00000000000000D+00 1.00000000000000D+00 2.00000000000000D+00
3.00000000000000D+00 4.00000000000000D+00 5.00000000000000D+00
6.00000000000000D+00 7.00000000000000D+00 8.00000000000000D+00
9.00000000000000D+00
'CONC ' 10 'REAL'
0.10495859E+02 0.10480556E+02 0.10465680E+02 0.10451221E+02
0.10437166E+02 0.10423511E+02 0.10410242E+02 0.10397354E+02
0.10384837E+02 0.10372684E+02
'DATAEND ' 0 'MESS'
test.bin
Description: Binary data
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