greetings,
i'm writing a program to scan a data file. from each line of the data file
i'd like to add something like below to a dictionary. my perl background
makes me want python to autovivify, but when i do:
file_data = {}
[... as i loop through lines in the file ...]
file_data[ md5sum ][ inode ] = { 'path' : path, 'size' : size, }
i get:
Traceback (most recent call last):
File "foo.py", line 45, in <module>
file_data[ md5sum ][ inode ] = { 'path' : path, 'size' : size, }
KeyError: '91b152ce64af8af91dfe275575a20489'
what is the pythonic way to build my "file_data" data structure above that
has the above structure?
on http://en.wikipedia.org/wiki/Autovivification there is a section on how
to do autovivification in python, but i want to learn how a python
programmer would normally build a data structure like this.
here is the code so far:
#!/usr/bin/python
import argparse
import os
ASCII_NUL = chr(0)
HOSTNAME = 0
MD5SUM = 1
FSDEV = 2
INODE = 3
NLINKS = 4
SIZE = 5
PATH = 6
file_data = {}
if __name__ == "__main__":
parser = argparse.ArgumentParser(description='scan files in a tree and
print a line of information about each regular file')
parser.add_argument('--file', '-f', required=True, help='File from which
to read data')
parser.add_argument('--field-separator', '-s', default=ASCII_NUL,
help='Specify the string to use as a field separator in output. The
default is the ascii nul character.')
args = parser.parse_args()
file = args.file
field_separator = args.field_separator
with open( file, 'rb' ) as f:
for line in f:
line = line.rstrip('\n')
if line == 'None': continue
fields = line.split( ASCII_NUL )
hostname = fields[ HOSTNAME ]
md5sum = fields[ MD5SUM ]
fsdev = fields[ FSDEV ]
inode = fields[ INODE ]
nlinks = int( fields[ NLINKS ] )
size = int( fields[ SIZE ] )
path = fields[ PATH ]
if size < ( 100 * 1024 * 1024 ): continue
### print "'%s' '%s' '%s' '%s' '%s' '%s' '%s'" % ( hostname, md5sum,
fsdev, inode, nlinks, size, path, )
file_data[ md5sum ][ inode ] = { 'path' : path, 'size' : size, }
thanks,
david
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