我有以下代码来使用我在网上找到的 arff.py 文件，但我不知道如何访问 arff 文件中的每一行或每一列。另外，如果这个 arff.py 文件不够好，你能把我链接到一个我可以索引它的行和列的 arff.py 吗？我不能使用外部库，我应该使用它的 .py 文件。
1 from arff import *
2 a = ArffFile.load('heart_train.arff')
3 print a.write()
这是 arff.py 文件：
# -*- coding: utf-8 -*-
# Copyright (c) 2008, Mikio L. Braun, Cheng Soon Ong, Soeren Sonnenburg
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
# * Neither the names of the Technical University of Berlin, ETH
# Zürich, or Fraunhofer FIRST nor the names of its contributors may be
# used to endorse or promote products derived from this software without
# specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import re, sys
class ArffFile(object):
"""An ARFF File object describes a data set consisting of a number
of data points made up of attributes. The whole data set is called
a 'relation'. Supported attributes are:
- 'numeric': floating point numbers
- 'string': strings
- 'nominal': taking one of a number of possible values
Not all features of ARFF files are supported yet. The most notable
exceptions are:
- no sparse data
- no support for date and relational attributes
Also, parsing of strings might still be a bit brittle.
You can either load or save from files, or write and parse from a
string.
You can also construct an empty ARFF file and then fill in your
data by hand. To define attributes use the define_attribute method.
Attributes are:
- 'relation': name of the relation
- 'attributes': names of the attributes
- 'attribute_types': types of the attributes
- 'attribute_data': additional data, for example for nominal attributes.
- 'comment': the initial comment in the file. Typically contains some
information on the data set.
- 'data': the actual data, by data points.
"""
def __init__(self):
"""Construct an empty ARFF structure."""
self.relation = ''
self.attributes = []
self.attribute_types = dict()
self.attribute_data = dict()
self.comment = []
self.data = []
pass
@staticmethod
def load(filename):
"""Load an ARFF File from a file."""
o = open(filename)
s = o.read()
a = ArffFile.parse(s)
o.close()
return a
@staticmethod
def parse(s):
"""Parse an ARFF File already loaded into a string."""
a = ArffFile()
a.state = 'comment'
a.lineno = 1
for l in s.splitlines():
a.__parseline(l)
a.lineno += 1
return a
def save(self, filename):
"""Save an arff structure to a file."""
o = open(filename, 'w')
o.write(self.write())
o.close()
def write(self):
"""Write an arff structure to a string."""
o = []
o.append('% ' + re.sub("\n", "\n% ", self.comment))
o.append("@relation " + self.esc(self.relation))
for a in self.attributes:
at = self.attribute_types[a]
if at == 'numeric':
o.append("@attribute " + self.esc(a) + " numeric")
elif at == 'string':
o.append("@attribute " + self.esc(a) + " string")
elif at == 'nominal':
o.append("@attribute " + self.esc(a) +
" {" + ','.join(self.attribute_data[a]) + "}")
else:
raise "Type " + at + " not supported for writing!"
o.append("\n@data")
for d in self.data:
line = []
for e, a in zip(d, self.attributes):
at = self.attribute_types[a]
if at == 'numeric':
line.append(str(e))
elif at == 'string':
line.append(esc(e))
elif at == 'nominal':
line.append(e)
else:
raise "Type " + at + " not supported for writing!"
o.append(','.join(line))
return "\n".join(o) + "\n"
def esc(self, s):
"Escape a string if it contains spaces"
if re.match(r'\s', s):
return "\'" + s + "\'"
else:
return s
def define_attribute(self, name, atype, data=None):
"""Define a new attribute. atype has to be one
of 'numeric', 'string', and 'nominal'. For nominal
attributes, pass the possible values as data."""
self.attributes.append(name)
self.attribute_types[name] = atype
self.attribute_data[name] = data
def __parseline(self, l):
if self.state == 'comment':
if len(l) > 0 and l[0] == '%':
self.comment.append(l[2:])
else:
self.comment = '\n'.join(self.comment)
self.state = 'in_header'
self.__parseline(l)
elif self.state == 'in_header':
ll = l.lower()
if ll.startswith('@relation '):
self.__parse_relation(l)
if ll.startswith('@attribute '):
self.__parse_attribute(l)
if ll.startswith('@data'):
self.state = 'data'
elif self.state == 'data':
if len(l) > 0 and l[0] != '%':
self.__parse_data(l)
def __parse_relation(self, l):
l = l.split()
self.relation = l[1]
def __parse_attribute(self, l):
p = re.compile(r'[a-zA-Z_][a-zA-Z0-9_]*|\{[^\}]+\}|\'[^\']+\'|\"[^\"]+\"')
l = [s.strip() for s in p.findall(l)]
name = l[1]
atype = l[2]
atypel = atype.lower()
if (atypel == 'real' or
atypel == 'numeric' or
atypel == 'integer'):
self.define_attribute(name, 'numeric')
elif atypel == 'string':
self.define_attribute(name, 'string')
elif atype[0] == '{' and atype[-1] == '}':
values = [s.strip () for s in atype[1:-1].split(',')]
self.define_attribute(name, 'nominal', values)
else:
self.__print_warning("unsupported type " + atype + " for attribute " + name + ".")
def __parse_data(self, l):
l = [s.strip() for s in l.split(',')]
if len(l) != len(self.attributes):
self.__print_warning("contains wrong number of values")
return
datum = []
for n, v in zip(self.attributes, l):
at = self.attribute_types[n]
if at == 'numeric':
if re.match(r'[+-]?[0-9]+(?:\.[0-9]*(?:[eE]-?[0-9]+)?)?', v):
datum.append(float(v))
elif v == '?':
datum.append(float('nan'))
else:
self.__print_warning('non-numeric value %s for numeric attribute %s' % (v, n))
return
elif at == 'string':
datum.append(v)
elif at == 'nominal':
if v in self.attribute_data[n]:
datum.append(v)
elif v == '?':
datum.append(None)
else:
self.__print_warning('incorrect value %s for nomial attribute %s' % (v, n))
return
self.data.append(datum)
def __print_warning(self, msg):
print ('Warning (line %d): ' % self.lineno) + msg
def dump(self):
"""Print an overview of the ARFF file."""
print "Relation " + self.relation
print " With attributes"
for n in self.attributes:
if self.attribute_types[n] != 'nominal':
print " %s of type %s" % (n, self.attribute_types[n])
else:
print (" " + n + " of type nominal with values " +
', '.join(self.attribute_data[n]))
for d in self.data:
print d
if __name__ == '__main__':
if False:
a = ArffFile.parse("""% yes
% this is great
@relation foobar
@attribute foo {a,b,c}
@attribute bar real
@data
a, 1
b, 2
c, d
d, 3
""")
a.dump()
a = ArffFile.load('heart_train.arff')
print a.write()