How do I assign a ListProperty with Google App Engine?
name = self.request.get("name")
description = self.request.get("description")
list = '''insert code here'''
I want list to work like a dictionary, is this possible with Google App Engine, if so, how:
[wordone : score; wordtwo : score; wordthree : score]
^I want the list property to store some data like this, how is this possible?
You actually won't be able to store a true dictionary as type in a ListProperty (it only supports datastore property types, of which dict is not one), so you won't be able to get the behavior you're looking for. Will all of the data be the same (i.e. each element represents a word score)? Assuming storing each word as its own property on the model doesn't make sense, one 'dirty' solution would be to make a ListProperty of type str, and then append the word and score as separate elements. Then, when you searched for a word in the list, you would return the value at the index position of the word + 1. That would looks something like:
class MyEntity(db.Model):
name = db.StringProperty()
description = db.TextProperty()
word_list = db.ListProperty()
You could then add words like:
new_entity = MyEntity()
new_entity.word_list = ['word1', 1, 'word2', 2, 'word3', 10]
You could then query for a particular entity and then examine its word_list property (a list), looking for your target word and returning the element one position after it.
More convoluted suggestion
However if that isn't an option, you could look into creating another model (let's say WordScore) that looked something like:
class WordScore(db.Model):
word = db.StringProperty()
score = db.IntegerProperty()
Then, whenever you needed to add a new score, you would create a WordScore instance, fill out the properties and then assign it to the proper entity. I haven't tested any of this, but the idea would be something like:
# Pull the 'other' entity (this would be your main class as defined above)
q = OtherEntity.all()
q.filter('name =', 'Someone')
my_entity = q.get()
# Create new score
ws = WordScore(parent=my_entity)
ws.word = 'dog'
ws.score = 2
ws.put()
You could then pull out the score for dog for 'Someone' by doing something like this (again, completely untested for now - be warned :) ):
# Get key of 'Someone'
q = OtherEntity.all()
q.filter('name =', 'Someone')
my_entity = q.get().key()
# Now get the score
ws = WordScore.all()
ws.filter('word = ', 'dog').ancestor(my_entity)
word_score = ws.get().score
Change to NDB and use the Pickle property:
Value is a Python object (such as a list or a dict or a string) that is serializable using Python's pickle protocol; the Datastore stores the pickle serialization as a blob. Unindexed by default.
NDB Properties
Then you can use it directly:
class table(ndb.Model):
data_dict = ndb.PickleProperty(default = {})
then
dd = table()
dd.data_dict['word_one'] = "Some_Score"
Related
I want to:
Take a list of lists
Make a frequency table in a dictionary
Do things with the resulting dictionary
The class works, the code works, the frequency table is correct.
I want to get a class that returns a dictionary, but I actually get a class that returns a class type.
I can see that it has the right content in there, but I just can't get it out.
Can someone show me how to turn the output of the class to a dictionary type?
I am working with HN post data. Columns, a few thousand rows.
freq_pph = {}
freq_cph = {}
freq_uph = {}
# Creates a binned frequency table:
# - key is bin_minutes (size of bin in minutes).
# - value is freq_value which sums/counts the number of things in that column.
class BinFreq:
def __init__(self, dataset, bin_minutes, freq_value, dict_name):
self.dataset = dataset
self.bin_minutes = bin_minutes
self.freq_value = freq_value
self.dict_name = dict_name
def make_table(self):
# Sets bin size
# Counts how of posts in that timedelta
if (self.bin_minutes == 60) and (self.freq_value == "None"):
for post in self.dataset:
hour_dt = post[-1]
hour_str = hour_dt.strftime("%H")
if hour_str in self.dict_name:
self.dict_name[hour_str] += 1
else:
self.dict_name[hour_str] = 1
# Sets bins size
# Sums the values of a given index/column
if (self.bin_minutes == 60) and (self.freq_value != "None"):
for post in self.dataset:
hour_dt = post[-1]
hour_str = hour_dt.strftime("%H")
if hour_str in self.dict_name:
self.dict_name[hour_str] += int(row[self.freq_value])
else:
self.dict_name[hour_str] = int(row[self.freq_value])
Instantiate:
pph = BinFreq(ask_posts, 60, "None", freq_pph)
pph.make_table()
How can pph be turned into a real dictionary?
If you want the make_table function to return a dictionary, then you have to add a return statement at the end of it, for example: return self.dict_name.
If you then want to use it outside of the class, you have to assign it to a variable, so in the second snipped do: my_dict = pph.make_table().
Classes can't return things – functions in classes could. However, the function in your class doesn't; it just modifies self.dict_name (which is a misnomer; it's really just a reference to a dict, not a name (which one might imagine is a string)), which the caller then reads (or should, anyway).
In addition, there seems to be a bug; the second if block (which is never reached anyway) refers to row, an undefined name.
Anyway, your class doesn't need to be a class at all, and is easiest implemented with the built-in collections.Counter() class:
from collections import Counter
def bin_by_hour(dataset, value_key=None):
counter = Counter()
for post in dataset:
hour = post[-1].hour # assuming it's a `datetime` object
if value_key: # count using `post[value_key]`
counter[hour] += post[value_key]
else: # just count
counter[hour] += 1
return dict(counter.items()) # make the Counter a regular dict
freq_pph = bin_by_hour(ask_posts)
freq_cph = bin_by_hour(ask_posts, value_key="num_comments") # or whatever
I am new to django so apologies if this is not possible or easy.
I have a view that takes a subset of a model
data = Terms.objects.filter(language = language_id)
The subset is one language. The set has a number of concepts for a language. Some languages might use the same word for multiple concepts, and I want to colour these the same in an SVG image. So I do this next:
for d in data:
if d.term is None:
d.colour = "#D3D3D3"
else:
d.colour = termColours[d.term]
Where termColours is a dictionary with keys as the unique terms and values as the hexadecimal colour I want.
I thought this would add a new colour attribute to my queryset. However, when I convert the queryset to json (in order to pass it to JS) the colour object is not there.
terms_json = serializers.serialize('json', data)
How can I add a new colour element to my queryset?
Convert your Queryset to Dict and then modify values.
Ex:
data = Terms.objects.filter(language = language_id).values()
for d in data:
if d.term is None:
d.colour = "#D3D3D3"
else:
d.colour = termColours[d.term]
If I understand correctly - you need Django ORM annotation. And it might look like that:
from django.db.models import Case, When, Value
data = Terms.objects.filter(language = language_id)
.annotate(color = Case(
When(term__isnull = True, then = "#D3D3D3"),
When(term__isnull = False, then = termColours[Value(term)]),))
Only problem here - I don't exactly know this moment - termColours[Value(term)], you need to test different combinations of that expressions to get the value of field term.
Is there any way to auto create objects in python
class A:
pass
a = A()
I would like to automatically create objects for a class.
I need to parse a bunch of xml and I'd like to create an object for one file (entry parse).
Or I need to create some random names?
You don't have to manually assign variable names to the object instances, simply store them in a list when you create them dynamically, like in this example where a list of objects gets created with information from a file:
class A:
def __init__(self, words):
self.words = words
a_objects = []
file = open("testfile.txt")
for line in file:
words = line.split()
a_objects.append(A(words))
If you need to access the objects directly using a key, you will have to use a dictionary instead of a list:
a_objects = {}
You can add key-value pairs to it like this:
words = line.split()
key = words[0]
a_objects[key] = A(words)
I have a number of chemicals with corresponding data held within a database, how do I go about returning a specific chemical, and its data, via its formula, eg o2.
class SourceNotDefinedException(Exception):
def __init__(self, message):
super(SourceNotDefinedException, self).__init__(message)
class tvorechoObject(object):
"""The class stores a pair of objects, "tv" objects, and "echo" objects. They are accessed
simply by doing .tv, or .echo. If it does not exist, it will fall back to the other variable.
If neither are present, it returns None."""
def __init__(self, echo=None, tv=None):
self.tv = tv
self.echo = echo
def __repr__(self):
return str({"echo": self.echo, "tv": self.tv}) # Returns the respective strings
def __getattribute__(self, item):
"""Altered __getattribute__() function to return the alternative of .echo / .tv if the requested
attribute is None."""
if item in ["echo", "tv"]:
if object.__getattribute__(self,"echo") is None: # Echo data not present
return object.__getattribute__(self,"tv") # Select TV data
elif object.__getattribute__(self,"tv") is None: # TV data not present
return object.__getattribute__(self,"echo") # Select Echo data
else:
return object.__getattribute__(self,item) # Return all data
else:
return object.__getattribute__(self,item) # Return all data
class Chemical(object):
def __init__(self, inputLine, sourceType=None):
self.chemicalName = TVorEchoObject()
self.mass = TVorEchoObject()
self.charge = TVorEchoObject()
self.readIn(inputLine, sourceType=sourceType)
def readIn(self, inputLine, sourceType=None):
if sourceType.lower() == "echo": # Parsed chemical line for Echo format
chemicalName = inputLine.split(":")[0].strip()
mass = inputLine.split(":")[1].split(";")[0].strip()
charge = inputLine.split(";")[1].split("]")[0].strip()
# Store the objects
self.chemicalName.echo = chemicalName
self.mass.echo = mass
self.charge.echo = charge
elif sourceType.lower() == "tv": # Parsed chemical line for TV format
chemicalName = inputLine.split(":")[0].strip()
charge = inputLine.split(":")[1].split(";")[0].strip()
mass = inputLine.split(";")[1].split("&")[0].strip()
# Store the objects
self.chemicalName.tv = chemicalName
self.charge.tv = charge
self.mass.tv = molecularWeight
else:
raise SourceNotDefinedException(sourceType + " is not a valid `sourceType`") # Otherwise print
def toDict(self, priority="echo"):
"""Returns a dictionary of all the variables, in the form {"mass":<>, "charge":<>, ...}.
Design used is to be passed into the Echo and TV style line format statements."""
if priority in ["echo", "tv"]:
# Creating the dictionary by a large, to avoid repeated text
return dict([(attributeName, self.__getattribute__(attributeName).__getattribute__(priority))
for attributeName in ["chemicalName", "mass", "charge"]])
else:
raise SourceNotDefinedException("{0} source type not recognised.".format(priority)) # Otherwise print
from ParseClasses import Chemical
allChemical = []
chemicalFiles = ("/home/temp.txt")
for fileName in chemicalFiles:
with open(fileName) as sourceFile:
for line in sourceFile:
allChemical.append(Chemical(line, sourceType=sourceType))
for chemical in allChemical:
print chemical.chemicalName #Prints all chemicals and their data in list format
for chemical in allChemical(["o2"]):
print chemical.chemicalName
outputs the following error which I have tried to remedy with no luck;
TypeError: 'list' object is not callable
The issue is the two lines
for chemical in allChemical(["o2"]):
print chemical.chemicalName
allChemical is a list, and you can't just do a_list(). It looks like you're trying to find either ['o2'] or just 'o2' in a list. To do that, you can get the index of the item and then get that index from the list.
allChemical[allChemical.index("o2")]
Try this function:
def chemByString(chemName,chemicals,priority="echo"):
for chemical in chemicals:
chemDict = chemical.toDict(priority)
if chemDict["chemicalName"] == chemName
return chemical
return None
This function is using the toDict() method found in the Chemical class. The code you pasted from the Chemical class explains that this method returns a dictionary from the chemical object:
def toDict(self, priority="echo"):
"""Returns a dictionary of all the variables, in the form {"mass":<>, "charge":<>, ...}.
Design used is to be passed into the Echo and TV style line format statements."""
if priority in ["echo", "tv"]:
# Creating the dictionary by a large, to avoid repeated text
return dict([(attributeName, self.__getattribute__(attributeName).__getattribute__(priority))
for attributeName in ["chemicalName", "mass", "charge"]])
else:
raise SourceNotDefinedException("{0} source type not recognised.".format(priority)) # Otherwise print
This dictionary looks like this:
"chemicalName" : <the chemical name>
"mass" : <the mass>
"charge" : <the charge>
What the function I created above does is iterate through all of the chemicals in the list, finds the first one with a name equal to "o2", and returns that chemical. Here's how to use it:
chemByString("o2",allChemicals).chemicalName
If the above does not work, may want to try using the alternative priority ("tv"), though I'm unsure if this will have any effect:
chemByString("o2",allChemicals,"tv").chemicalName
If the chemical isn't found, the function returns None:
chemByString("myPretendChemical",allChemicals).chemicalName
EDIT: See my new answer. Leaving this one here since it might still be helpful info.
In python, a list object is a structure holding other objects with an index for each object it contains. Like this:
Index Object
0 "hello"
1 "world"
2 "spam"
If you want to get to one of those objects, you have to know its index:
objList[0] #returns "hello" string object
If you don't know the index, you can find it using the index method:
objList.index("hello") #returns 0
Then you can get the object out of the list using the found index:
objList[objList.index("hello")]
However this is kind of silly, since you can just do:
"hello"
Which in this case will produce the same result.
Your allChemical object is a list. It looks like the line chemicalFiles = ("/home/temp.txt") is filling your list with some type of object. In order to answer your question, you have to provide more information about the objects which the list contains. I assume that information is in the ParseClasses module you are using.
If you can provide more information about the Chemical object you are importing, that may go a long way to helping solve your problem.
IF the objects contained in your list are subclassed from str, this MAY work:
allChemical[allChemical.index("o2")].chemicalName
"02" is a str object, so index is going to look for a str object (or an object subclassed from str) in your list to find its index. However, if the object isn't a string, it will not find it.
As a learning exercise, try this:
class Chemical(str):
'''A class which is a subclass of string but has additional attributes such as chemicalName'''
def __init__(self,chemicalName):
self.chemicalName = chemicalName
someChemicals = [Chemical('o2'),Chemical('n2'),Chemical('h2')]
for chemical in someChemicals: print(chemical.chemicalName)
#prints all the chemical names
print(someChemicals[0].chemicalName)
#prints "o2"; notice you have to know the index ahead of time
print(someChemicals[someChemicals.index("o2")].chemicalName)
#prints "o2" again; this time index found it for you, but
#you already knew the object ahead of time anyway, sot it's a little silly
This works because index is able to find what you are looking for. If it isn't a string it can't find it, and if you don't know what index 'o2' is at, if you want to get to a specific chemical in your list of chemicals you're going to have to learn more about those objects.
So my problem below is that when it sends the json object lets say I have multiple items in the lists? well it sends that many objects except changing that field once in the dict that i created above. For some reason , even though I use the for loops above to create a string from the list it doesn't actually make it so and i get 15 objects instead of 1 object with maybe a field that has 15 things in it separated by commas.
my expected output should be
name,special1,special2,special3..etc, review1,review2
instead i get
name,special1,review1
name,special2,review1
name,special3,review1
etc..
name,special1,review2
name,special1,review3
My main question is how do I convert the list to an array or even just to a string(like a toString Method) so that my json dump doesn't spit out multiples?
class store(db.Model):
mykey = db.StringProperty(db.Key)
storeSpecial = db.ListProperty(item_type=str)
reviews = db.ListProperty(item_type=str)
storeName = db.StringProperty()
#later in the code
qy1 = GqlQuery("SELECT storeName,storeSpecial,reviews FROM store WHERE mykey =:1",dataInput)
records_to_send = []
for i in qy1:
rev =""
for k in i.review:
rev = rev + str(k) + ","
spec = ""
for k2 in i.storeSpecial:
spec = spec + str(k2) + ","
output = {"store name": i.storeName,"specials": spec,"reviews":rev}
records_to_send.append(output)
self.response.out.write(json.dumps(records_to_send))
I'm not really sure what you want, your example is confusing. If you use JSON, why not just keep it as list? Why do you change it to a string?
It seems you want something like this
for store in qy1:
records_to_send.append({'store name': store.storeName, 'specials': store.storeSpecial}, 'reviews': store.reviews})