I'm using python3 and when trying to run the following code, I'm facing the error:
NameError: name '_length' is not defined
The code itself:
class OFPHELLO(GenericStruct):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self._length = self.get_size()
_msg_type = OFPType.OFPT_HELLO
_build_order = ('header', 'x')
header = OFPHeader(type = _msg_type, length = _length)
x = UBInt8()
The problem is the _length variable that I'm passing in OFPHeader, the value of which is computed in GenericStruct. How can I compute the _length variable inside the OFPHELLO class and use it as parameter in the OFPHeader class?
Following the GenericStruct code:
class GenericStruct(object):
def __init__(self, **kwargs):
for a in kwargs:
try:
field = getattr(self, a)
field.value = kwargs[a]
except AttributeError:
raise OFPException("Attribute error: %s" % a)
def build(self):
hexa = ""
for field in self._build_order:
hexa += getattr(self, field).build()
return hexa
def parse(self, buff):
begin = 0
for field in self._build_order:
size = getattr(self, field).get_size()
getattr(self,field).parse(buff, offset=begin)
begin += size
def get_size(self):
tot = 0
for field in self._build_order:
tot += getattr(self, field).get_size()
return tot
- how have you defined (GenericStruct)
- header = OFPHeader(type = _msg_type, length = _lenght)
- correct the spelling to _length
-- and please post the entire code next time
Related
Hi I'm having a problem in this classes I created the parent class extracao_nia with the method aplica_extracao for having the similar part of the execution that I use in others class and the diferent part is in the transform method definined in the children class
but I'm having an issue that the variables that I defined as list() are Null variable when I execute the code:
AttributeError: 'NoneType' object has no attribute 'append'
class extracao_nia:
def __init__(self, d=1, h=1, m=15):
self._data_base = "database"
self.UM_DIA = datetime.timedelta(days=d)
self.UMA_HORA = datetime.timedelta(hours=h)
self.INTERVALO = datetime.timedelta(minutes=m)
#property
def data_base(self):
return self._data_base
def aplica_extracao(self, SQL):
fim_intervalo = self.inicio + self.INTERVALO#
pbar = self.cria_prog_bar(SQL)#
while (fim_intervalo <= self.FIM):#
self.connector.execute(SQL,(self.inicio.strftime('%Y-%m-%d %H:%M'),fim_intervalo.strftime('%Y-%m-%d %H:%M')))#
for log in self.connector:#
self.transforma(log)
self.inicio = fim_intervalo
fim_intervalo = self.inicio + self.INTERVALO
class usuarios_unicos(extracao_nia):
def __init__(self, d=1, h=1, m=15, file='nodes.json'):
self._data_base = "database"
self.UM_DIA = datetime.timedelta(days=d)
self.UMA_HORA = datetime.timedelta(hours=h)
self.INTERVALO = datetime.timedelta(minutes=m)
self.file = file
self.ids = list()
self.nodes = list()
self.list_cpf = list()
def transforma(self, log):
context = json.loads(log[0])['context']
output = json.loads(log[0])['output']
try:
nr_cpf = context['dadosDinamicos']['nrCpf']
conversation_id = context['conversation_id']
nodes_visited = output['output_watson']['nodes_visited']
i = self.ids.index(conversation_id)
atual = len(self.nodes[i])
novo = len(nodes_visited)
if novo > atual:
nodes[i] = nodes_visited
except KeyError:
pass
except ValueError:
self.ids.append(conversation_id)
self.nodes = self.nodes.append(nodes_visited)
self.list_cpf = self.list_cpf.append(nr_cpf)
list.append returns None since it is an in-place operation, so
self.nodes = self.nodes.append(nodes_visited)
will result in self.nodes being assigned None. Instead you can just use
self.nodes += nodes_visited
I'm new to python and am currently trying to use an old module to output graphs. The code below is a excerpt from the module that uses rpy to design
standard celeration charts (don't look it up).
I'm having trouble understanding how the class Element and class Vector work together.
I've been trying to pass the a element object to the vector get_elements but I'm not sure if that's what I should be doing.
Any help would be appreciated. Thanks!
class Element(object):
"""Base class for Chartshare vector elements."""
def __init__(self, offset=0, value=0):
self.offset=offset
self.value=value
self.text=''
def setText(self, value):
self.value=value
def getText(self):
return self.value
text = property(getText, setText)
class Vector(object):
"""Base class for Chartshare Vectors."""
def __init__(self, name='', color='black', linetype='o', symbol=1, clutter=0, start=0, end=140, continuous=False, debug=False):
self.name=name
self.color=color
self.linetype=linetype
self.symbol=symbol
self.start=start
self.end=end
self.elements={}
self.debug=debug
self.continuous=continuous
if not self.continuous:
for i in range(self.start, self.end+1):
self.elements[i]='NaN'
def getSymbol(self):
return self._symbol
def setSymbol(self, value):
if (type(value) == int):
if (value >= 0) and (value <= 18):
self._symbol = value
else:
raise SymbolOutOfRange, "Symbol should be an integer between 0 and 18."
elif (type(value) == str):
try:
self._symbol = value[0]
except IndexError:
self._symbol=1
else:
self._symbol = 1
symbol = property(getSymbol, setSymbol)
def getLinetype(self):
return self._linetype
def setLinetype(self, value):
if (value == 'p') or (value == 'o') or (value == 'l'):
self._linetype = value
else:
raise InvalidLinetype, "Line type should be 'o', 'p', or 'l'"
linetype = property(getLinetype, setLinetype)
def get_elements(self):
"""Returns a list with the elements of a Vector."""
retval = []
for i in range(self.start, self.end+1):
if (not self.continuous):
retval.append(self.elements[i])
else:
if (self.elements[i] != 'NaN'):
retval.append(self.elements[i])
return retval
def get_offsets(self):
"""Returns a list of the offsets of a Vector."""
retval = []
for i in range(self.start, self.end+1):
if (not self.continuous):
retval.append(i)
else:
if (self.elements[i] == 'NaN'):
retval.append(i)
return retval
def to_xml(self, container=False):
"""Returns an xml representation of the Vector."""
if (container == False):
container = StringIO.StringIO()
xml = XMLGenerator(container)
attrs = {}
attrs[u'name'] = u"%s" % self.name
attrs[u'symbol'] = u"%s" % self.symbol
attrs[u'linetype'] = u"%s" % self.linetype
attrs[u'color'] = u"%s" % self.color
xml.startElement(u'vector', attrs)
for i in range(self.start, self.end+1):
if (self.elements[i] != 'NaN'):
attrs.clear()
attrs[u'offset'] = u"%s" % i
xml.startElement(u'element', attrs)
xml.characters(u"%s" % self.elements[i])
xml.endElement(u'element')
xml.endElement(u'vector')
def render(self):
"""Plots the current vector."""
if (self.debug):
print "Rendering Vector: %s" % self.name
print self.elements
r.points(x=range(self.start, self.end+1),
y=self.elements,
col=self.color,
type=self.linetype,
pch=self.symbol)
if (self.debug):
print "Finished rendering Vector: %s" % self.name
Vector's get_elements() doesn't take any arguments. Well, technically it does. It takes self. self is syntactic sugar that lets you do this:
vec = Vector()
vec.get_elements()
It's equivalent to this:
vec = Vector()
Vector.get_elements(vec)
Since get_elements() doesn't take any arguments, you can't pass a to it. Skimming the code, I don't see a set_elements() analog. This means you'll have to modify the vector's element's dictionary directly.
vec = Vector()
vec.elements[a] = ...
print(vec.get_elements()) # >>> [a,...]
As I can see, there is no place in this code where you are assigning self.elements with any input from a function. You are only initialising it or obtaining values
Also note that the .get_elements() function doesn't have any arguments (only self, that is the object where you are calling it in), so of course it won't work.
Unless you can do something such as the following, we would need more code to understand how to manipulate and connect these two objects.
element_obj = Element()
vector_obj = Vector()
position = 4
vector_obj.elements[4] = element_obj
I got to this answer with the following: as I can see, the elements property in the Vector class is a dictonary, that when you call vector_obj.get_elements() is casted to an array using the start and end parameters as delimiters.
Unless there is something else missing, this would be the only way I could think out of adding the an element into a vector object. Otheriwse, we would need some more code or context to understand how these classes behave with each other!
Hope it helps!
I read several post about the nested class, but this mechanism is still not clear for me.
Basically what I want to do is define a class (to solve ordinary differential equation in which I define one class for each order of accuracy )
Here's the class :
class AdamsBashforth(AdamsMethods):
class _2nd(AdamsMethods):
startup = False
def __init__(self, dydt : Rhs, filename :str = None , salve : bool = True ):
self.file = filename
self.save = save
super().__init__(dydt)
def solve(self):
self.time , self.u = self.dydt.createArray()
u[1] = rungekutta.RK2.step(self.dydt.f, time[0], u[0], self.dt)
for i in range(1,len(self.time)-1):
self.u[i+1] = u[i] + self.dt/2*(3*self.dydt.f(self.time[i],self.u[i])-self.dydt.f(self.time[i-1],self.u[i-1]))
AdamsBashforth._2nd.solved = True
if self.file != None:
super().write2file()
if self.save:
return self.time,self.u
def plot(self):
if AdamsBashforth._2nd.solved:
super().plot('Sys ODE solution using Adams-Bashforth 2nd order','time [s]','y(t)')
else:
print("Unsolved problem, call `solve` method before")
#classmethod
def step(cls, func , t : np.float , u : np.float, dt ):
def f(ti,ui):
return np.array([function(ti,ui) for function in func])
if AdamsBashforth._2nd.startup == False:
#print ("AB start-up")
AdamsBashforth.u1 = rungekutta.RK2.step(func,t,u,dt)
AdamsBashforth.startup = True
unext = AdamsBashforth.u1 + dt/2.*(3.*f(t+dt,AdamsBashforth.u1) - f(t,u))
AdamsBashforth.u1 = u
return unext
Here's the way that I would really like to do is to call:
problem = AdamsBashforth._2nd(dydt)
but i receive an error that says that adamsbashforth has no member _2nd
so I've try to doing so .. but still the same message :
class AdamsBashforth(AdamsMethods):
def __init__(self, dydt, filename :str = None , salve : bool = True):
self._2nd = self._2nd(dydt,filename,salve)
def solve(self):
pass
class _2nd(AdamsMethods):
What is the right way in order to obtain a call like the first (problem = AdamsBashforth._2nd(dydt))
and using the class _2nd
EDIT
class AdamsBashforth(AdamsMethods):
def __init__(self, dydt, filename :str = None , save : bool = True):
self._2nd = AdamsBashforth._2nd(dydt,filename,save)
def solve(self):
pass
class _2nd(AdamsMethods):
startup = False
solved = False
def __init__(self, dydt : Rhs, filename :str = None , save : bool = True ):
self.file = filename
self.save = save
super().__init__(dydt)
def solve(self):
self.time , self.u = self.dydt.createArray()
self.u[1] = rungekutta.RK2.step(self.dydt.f, self.time[0], self.u[0], self.dt)
for i in range(1,len(self.time)-1):
self.u[i+1] = u[i] + self.dt/2*(3*self.dydt.f(self.time[i],self.u[i])-self.dydt.f(self.time[i-1],self.u[i-1]))
_2nd.solved = True
if self.file != None:
super().write2file()
if self.save:
return self.time,self.u
def plot(self):
if AdamsBashforth._2nd.solved:
super().plot('Sys ODE solution using Adams-Bashforth 2nd order','time [s]','y(t)')
else:
print("Unsolved problem, call `solve` method before")
#classmethod
def step(cls, func , t : np.float , u : np.float, dt ):
def f(ti,ui):
return np.array([function(ti,ui) for function in func])
if AdamsBashforth._2nd.startup == False:
#print ("AB start-up")
AdamsBashforth.u1 = rungekutta.RK2.step(func,t,u,dt)
AdamsBashforth.startup = True
unext = AdamsBashforth.u1 + dt/2.*(3.*f(t+dt,AdamsBashforth.u1) - f(t,u))
AdamsBashforth.u1 = u
return unext
calling in this way :
ab2_p1 = adamsmethods.AdamsBashforth(problem1, 'ab2_1.dat')
ab2t,ab2u = ab2_p1._2nd.solve()
ab2_p1.plot()
looks that work .. but I don't know why ... and I don't know if is it the correct way !!
but I have still problem in order to call the classmethod for example :
u = adamsmethods.AdamsBashforth._2nd.step(func0,t,u,dt)
doesn't work :
Traceback (most recent call last):
File "drive.py", line 287, in <module>
main()
File "drive.py", line 149, in main
u = adamsmethods.AdamsBashforth._2nd.step(func0,t,u,dt)
AttributeError: type object '_2nd' has no attribute 'step'
------------------------------------------------------------
I am trying to replicate something similar to model queries in Django.
# database.py
class ModelFactory(object):
def __init__(self, table):
self.table = table
def fields(self, *args):
str_columns = ''
for count, arg in enumerate(args):
if count == 0:
str_columns += arg
else:
str_columns += ', %s' % arg
self.str_columns = str_columns
def wheres(self, **kwargs):
str_wheres = ''
for count, (key, value) in enumerate(kwargs.items()):
if count == 0:
str_wheres += 'WHERE %s = %s' % (key, value)
else:
str_wheres += ' AND %s = %s' % (key, value)
self.str_wheres = str_wheres
My idea is to use it as follows:
from database import ModelFactory
myInstance = ModelFactory('myTable')
myQuery = myInstance.fields('column1', 'column2').wheres(column1 = 5)
I am not sure if I need a new class or function inside ModelFactory class that would take the results from 'fields' and 'wheres' to compile a SQL string to query? Like the following line:
cur.execute('SELECT column1, column2 from myTable WHERE column1 = 5')
I am also not sure if calling class.function1.function2 is correct? Django has the 'objects' word, e.g. Instance.objects.filter().exclude()
I have tried to change the code base as follows:
# database.py
class ModelFactory(object):
def __init__(self, table):
self.table = table
def objects(self):
def fields(self, **kwargs):
return self.f(**kwargs)
def wheres(self, *args):
return self.w(*args)
def f(self, *args):
str_columns = ''
for count, arg in enumerate(args):
if count == 0:
str_columns += arg
else:
str_columns += ', %s' % arg
self.str_columns = str_columns
def w(self, **kwargs):
str_wheres = ''
for count, (key, value) in enumerate(kwargs.items()):
if count == 0:
str_wheres += 'WHERE %s = %s' % (key, value)
else:
str_wheres += ' AND %s = %s' % (key, value)
self.str_wheres = str_wheres
But when I try the following:
from database import ModelFactory
myInstance = ModelFactory('myTable')
myQuery = myInstance.objects.fields('column1', 'column2').wheres(column1 = 5)
I get an AttributeError: 'function' object has no attribute 'fields'
If you want to chain object's method calls, you need to return that object from method. i.e. add return self to your methods.
So your class declaration probably should be something like the following:
class ModelFactory(object):
def __init__(self, table):
self.table = table
def fields(self, *args):
self.str_columns = ', '.join(args)
return self
def wheres(self, **kwargs):
str_wheres = ' AND '.join('{} = {}'.format(k, v) for k, v in kwargs.items())
self.str_wheres = 'WHERE {}'.format(str_wheres)
return self
def execute(self):
// ATTN! This code is prone to SQL injection. Do not use!
cur.execute('SELECT {columns} FROM {table} {wheres}'.format(columns=self.str_columns, table=self.table, wheres=self.wheres))
The problem is that you still have objects as a function:
def objects(self):
Currently, this means that you'll need to call it as a function - your myQuery line would need to look something like:
myQuery = myInstance.objects().fields(...
However, that still wouldn't be enough because fields and wheres are both only scoped within the objects function.
If you want to push down this route, then you will need to create a class that you instantiate inside your model under the attribute objects - Django uses QuerySet for this. If you check out the source you'll see how much magic is required to make something "simple" like objects work.
So a simple alternative?
You will have to make a new class similar to QuerySet which can provide the fields and wheres chainable functions - let's call it WernerfeuerSet:
class WernerfeuerSet:
def __init__(self, table):
self.table = table
def fields(self, **kwargs):
pass
def wheres(self, **kwargs):
pass
And now instantiate that within your ModelFactory - something like:
class ModelFactory:
def __init__(self, table):
self.objects = WernerfeuerSet(table)
Now your original query should be possible because objects is an attribute of the ModelFactory, rather than a function:
myQuery = myInstance.objects.fields('column1', 'column2').wheres(column1 = 5)
I want to compress my movies automatically. So I've written a mediainfo wrapper class in python, to generate a xml output, which I then parse to a movieinfo class, with a list of audio and subtitle tracks.
__author__ = 'dominik'
class Error(Exception):
""" Error class
"""
class ValidationError(Error):
""" Invalid or missing xml items
"""
class MovieInfo(object):
""" Description of movie file
"""
def __init__(self, media_info):
self._video_track = None
self._audio_tracks = []
self._subtitle_tracks = []
self.valid_movie = True
for track in media_info.tracks:
if track.track_type == "Audio":
self._audio_tracks.append(AudioTrack(track))
elif track.track_type == "Text":
self._subtitle_tracks.append(SubtitleTrack(track))
elif track.track_type == "Video":
self._video_track = VideoTrack(track)
#property
def audio_tracks(self):
if not hasattr(self, "_audio_tracks"):
self._audio_tracks = []
if len(self._audio_tracks) != 0:
return self._audio_tracks
#property
def subtitle_tracks(self):
if not hasattr(self, "_subtitle_tracks"):
self._subtitle_tracks = []
if len(self._subtitle_tracks) != 0:
return self._subtitle_tracks
class Track(object):
""" Abstract track class for audio and subtitle tracks
"""
__KNOWN_LANGUAGE_CODES = {"en": "ENG", "de": "DE"}
def __init__(self, track, valid_codecs):
self._valid = True
track_id = int(track.id)
codec_id = self._determine_codec(track.codec_id, valid_codecs)
language = self._determine_language(track.language)
self._id = track_id
self._codec_id = codec_id
self._language = language
def _determine_codec(self, track_codec, types):
result = types.get(track_codec, None)
if result is None:
self._valid = False
return result
def _determine_language(self, track_language, types=__KNOWN_LANGUAGE_CODES):
result = types.get(track_language, None)
if result is None:
self._valid = False
return result
class AudioTrack(Track):
""" Audio track class
"""
__KNOWN_AUDIO_CODECS = {"A_DTS": "DTS", "A_AC3": "AC3"}
def __init__(self, track):
self._type = 1
Track.__init__(self, track, self.__KNOWN_AUDIO_CODECS)
class SubtitleTrack(Track):
""" Subtitle track class
"""
__KNOWN_SUBTITLE_CODECS = {"S_VOBSUB": "VOBSUB"}
def __init__(self, track):
self._type = 2
if track.forced == "Yes":
self._forced = True
else:
self._forced = False
Track.__init__(self, track, self.__KNOWN_SUBTITLE_CODECS)
class VideoTrack(object):
""" Video track class (only one video track in movie info!)
"""
def __init__(self, track):
self._type = 0
self._framerate = float(track.frame_rate)
self._width = track.width
self._height = track.height
Here is the mediainfo class (it's the pymediainfo class):
from subprocess import Popen
import os
from tempfile import mkstemp
from bs4 import BeautifulSoup, NavigableString
from setuptools.compat import unicode
class Track(object):
""" Hold the track information
"""
def __getattr__(self, item):
try:
return object.__getattribute__(self, item)
except:
pass
return None
def __init__(self, xml_track):
self.xml_track = xml_track
self.track_type = xml_track.attrs["type"]
for child in self.xml_track.children:
if not isinstance(child, NavigableString):
node_name = child.name.lower().strip()
node_value = unicode(child.string)
node_other_name = "other_%s" % node_name
if getattr(self, node_name) is None:
setattr(self, node_name, node_value)
else:
if getattr(self, node_other_name) is None:
setattr(self, node_other_name, [node_value, ])
else:
getattr(self, node_other_name).append(node_value)
for key in [c for c in self.__dict__.keys() if c.startswith("other_")]:
try:
primary = key.replace("other_", "")
setattr(self, primary, int(getattr(self, primary)))
except:
for value in getattr(self, key):
try:
actual = getattr(self, primary)
setattr(self, primary, int(value))
getattr(self, key).append(actual)
break
except:
pass
def __repr__(self):
return("<Track id='{0}', type='{1}'>".format(self.id, self.track_type))
def to_data(self):
data = {}
for k, v in self.__dict__.items():
if k != 'xml_track':
data[k] = v
return data
class Mediainfo(object):
""" MediaInfo wrapper
"""
def __init__(self, xml):
self.xml_dom = xml
if isinstance(xml, str):
self.xml_dom = BeautifulSoup(xml, "xml")
def _populate_tracks(self):
if self.xml_dom is None:
return
for xml_track in self.xml_dom.Mediainfo.File.find_all("track"):
self._tracks.append(Track(xml_track))
#property
def tracks(self):
if not hasattr(self, "_tracks"):
self._tracks = []
if len(self._tracks) == 0:
self._populate_tracks()
return self._tracks
#staticmethod
def parse(filename):
filehandler_out, filename_out = mkstemp(".xml", "mediainfo-")
filehandler_err, filename_err = mkstemp(".error", "mediainfo-")
filepointer_out = os.fdopen(filehandler_out, "r+b")
filepointer_err = os.fdopen(filehandler_err, "r+b")
mediainfo_command = ["mediainfo", "-f", "--Output=XML", filename]
p = Popen(mediainfo_command, stdout=filepointer_out, stderr=filepointer_err)
p.wait()
filepointer_out.seek(0)
xml_dom = BeautifulSoup(filepointer_out.read(), "xml")
filepointer_out.close()
filepointer_err.close()
print(xml_dom)
return Mediainfo(xml_dom)
def to_data(self):
data = {'tracks': []}
for track in self.tracks:
data['tracks'].append(track.to_data())
return data
This class gives me every track in the xml and then I parse the relevant info in movieinfo.
Ok now I have a list of audiotracks e.g. 3 tracks one in german language and DTS, one in german and AC3 and one in english and AC3. Now I want to get the ids from the tracks in the format "1,2,3" to give it to handbrake cli.
My problem is the order of the tracks. If there is a german DTS track this schould be the first track, the second track should be also the first, but compressed to aac and the third track should be one english track in AAC. If there is only a german AC3 track then the first track should be this track but compressed to AAC, and the second track should englisch and AAC.
I don't know exactly how I can achive that, can you help me? I'm new to python, and come from C, C++ and C#. In C# this is very easy to get with lambda.
Assuming you know to define a compare-tor that given two items can define which is bigger then Python functions as well as C or C++.
Start here -
1. https://wiki.python.org/moin/HowTo/Sorting/
https://developers.google.com/edu/python/sorting
http://docs.python.org/2/library/functions.html#sorted
Using sorted method and define the key you want.