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# -*- coding: utf-8 -*-
# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of logilab-common.
#
# logilab-common is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option) any
# later version.
#
# logilab-common is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with logilab-common. If not, see <http://www.gnu.org/licenses/>.
"""This is a DBF reader which reads Visual Fox Pro DBF format with Memo field
Usage:
>>> rec = readDbf('test.dbf')
>>> for line in rec:
>>> print line['name']
:date: 13/07/2007
http://www.physics.ox.ac.uk/users/santoso/Software.Repository.html
page says code is "available as is without any warranty or support".
"""
import struct
import os, os.path
import sys
import csv
import tempfile
class Dbase:
def __init__(self):
self.fdb = None
self.fmemo = None
self.db_data = None
self.memo_data = None
self.fields = None
self.num_records = 0
self.header = None
self.memo_file = ''
self.memo_header = None
self.memo_block_size = 0
self.memo_header_len = 0
def _drop_after_NULL(self, txt):
for i in range(0, len(txt)):
if ord(struct.unpack('c', txt[i])[0])==0:
return txt[:i]
return txt
def _reverse_endian(self, num):
if not len(num):
return 0
val = struct.unpack('<L', num)
val = struct.pack('>L', val[0])
val = struct.unpack('>L', val)
return val[0]
def _assign_ids(self, lst, ids):
result = {}
idx = 0
for item in lst:
id = ids[idx]
result[id] = item
idx += 1
return result
def open(self, db_name):
filesize = os.path.getsize(db_name)
if filesize <= 68:
raise IOError, 'The file is not large enough to be a dbf file'
self.fdb = open(db_name, 'rb')
self.memo_file = ''
if os.path.isfile(db_name[0:-1] + 't'):
self.memo_file = db_name[0:-1] + 't'
elif os.path.isfile(db_name[0:-3] + 'fpt'):
self.memo_file = db_name[0:-3] + 'fpt'
if self.memo_file:
#Read memo file
self.fmemo = open(self.memo_file, 'rb')
self.memo_data = self.fmemo.read()
self.memo_header = self._assign_ids(struct.unpack('>6x1H', self.memo_data[:8]), ['Block size'])
block_size = self.memo_header['Block size']
if not block_size:
block_size = 512
self.memo_block_size = block_size
self.memo_header_len = block_size
memo_size = os.path.getsize(self.memo_file)
#Start reading data file
data = self.fdb.read(32)
self.header = self._assign_ids(struct.unpack('<B 3B L 2H 20x', data), ['id', 'Year', 'Month', 'Day', '# of Records', 'Header Size', 'Record Size'])
self.header['id'] = hex(self.header['id'])
self.num_records = self.header['# of Records']
data = self.fdb.read(self.header['Header Size']-34)
self.fields = {}
x = 0
header_pattern = '<11s c 4x B B 14x'
ids = ['Field Name', 'Field Type', 'Field Length', 'Field Precision']
pattern_len = 32
for offset in range(0, len(data), 32):
if ord(data[offset])==0x0d:
break
x += 1
data_subset = data[offset: offset+pattern_len]
if len(data_subset) < pattern_len:
data_subset += ' '*(pattern_len-len(data_subset))
self.fields[x] = self._assign_ids(struct.unpack(header_pattern, data_subset), ids)
self.fields[x]['Field Name'] = self._drop_after_NULL(self.fields[x]['Field Name'])
self.fdb.read(3)
if self.header['# of Records']:
data_size = (self.header['# of Records'] * self.header['Record Size']) - 1
self.db_data = self.fdb.read(data_size)
else:
self.db_data = ''
self.row_format = '<'
self.row_ids = []
self.row_len = 0
for key in self.fields:
field = self.fields[key]
self.row_format += '%ds ' % (field['Field Length'])
self.row_ids.append(field['Field Name'])
self.row_len += field['Field Length']
def close(self):
if self.fdb:
self.fdb.close()
if self.fmemo:
self.fmemo.close()
def get_numrecords(self):
return self.num_records
def get_record_with_names(self, rec_no):
"""
This function accept record number from 0 to N-1
"""
if rec_no < 0 or rec_no > self.num_records:
raise Exception, 'Unable to extract data outside the range'
offset = self.header['Record Size'] * rec_no
data = self.db_data[offset:offset+self.row_len]
record = self._assign_ids(struct.unpack(self.row_format, data), self.row_ids)
if self.memo_file:
for key in self.fields:
field = self.fields[key]
f_type = field['Field Type']
f_name = field['Field Name']
c_data = record[f_name]
if f_type=='M' or f_type=='G' or f_type=='B' or f_type=='P':
c_data = self._reverse_endian(c_data)
if c_data:
record[f_name] = self.read_memo(c_data-1).strip()
else:
record[f_name] = c_data.strip()
return record
def read_memo_record(self, num, in_length):
"""
Read the record of given number. The second parameter is the length of
the record to read. It can be undefined, meaning read the whole record,
and it can be negative, meaning at most the length
"""
if in_length < 0:
in_length = -self.memo_block_size
offset = self.memo_header_len + num * self.memo_block_size
self.fmemo.seek(offset)
if in_length<0:
in_length = -in_length
if in_length==0:
return ''
return self.fmemo.read(in_length)
def read_memo(self, num):
result = ''
buffer = self.read_memo_record(num, -1)
if len(buffer)<=0:
return ''
length = struct.unpack('>L', buffer[4:4+4])[0] + 8
block_size = self.memo_block_size
if length < block_size:
return buffer[8:length]
rest_length = length - block_size
rest_data = self.read_memo_record(num+1, rest_length)
if len(rest_data)<=0:
return ''
return buffer[8:] + rest_data
def readDbf(filename):
"""
Read the DBF file specified by the filename and
return the records as a list of dictionary.
:param: filename File name of the DBF
:return: List of rows
"""
db = Dbase()
db.open(filename)
num = db.get_numrecords()
rec = []
for i in range(0, num):
record = db.get_record_with_names(i)
rec.append(record)
db.close()
return rec
if __name__=='__main__':
rec = readDbf('dbf/sptable.dbf')
for line in rec:
print '%s %s' % (line['GENUS'].strip(), line['SPECIES'].strip())
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