I seem to be making a stupid mistake that I cant find. Im simply trying to call my functions from my record class and having an invalid syntax error despite looking at sample code and trying to emulate the syntax.
Ive tried following tutorials and calling the function in every which way so the problem may not be in the calling of the function but something else I feel.
class definitions
class record:
def __init__(self,telephone,lastname,firstname):
self.telephone = telephone
self.lastname = lastname
self.firstname = firstname
def addrecord(self,x,y,z):
x = input('Enter telephone number')
y = input('Enter lastname')
z = input('Enter firstname')
phonebook.append(record(x,y,z))
return
def deleterecord(self,x):
phonebook[x-1].pop
return
Main
phonebook = record[]
addrecord(515,'fin','matt')
print(phonebook[0].firstname)
deleterecord(1)
print(phonebook[0].firstname)
If all this works I expect the output to be
"matt"
"null"
There are a number of problems with your code:
you are defining phonebook otuside of the class
in deleterecord you should call phonebook.pop(x).
there should be two classes that handle the phonebook and records, and the record could be modeled using a namedtuple.
there are syntax errors like calling record[] which is not valid Python.
Alternative implementation:
from collections import namedtuple
PhoneRecord = namedtuple("PhoneRecord", ['firstname', 'lastname', 'telephone'])
class PhoneBook:
def __init__(self):
self._phonebook = []
def addrecord(self, record):
self._phonebook.append(record)
return self._phonebook.index(record)
def deleterecord(self, i):
self._phonebook.pop(i)
phonebook = PhoneBook()
record_index = phonebook.addrecord(PhoneRecord(firstname="matt", lastname="snow", telephone="25512521"))
print(phonebook._phonebook)
phonebook.deleterecord(record_index)
print(phonebook._phonebook)
which will yield in the console:
[PhoneRecord(firstname='matt', lastname='snow', telephone='25512521')]
[]
The simplified version of your question is, given code
records = []
records.append("matt")
print(records[0])
del records[0]
print(records[0])
why don't I get the following output
"matt"
None
Instead, you get an IndexError exception.
The reason is that you are accessing an element beyond the size of the list, and Python handles this by raising an exception rather than returning None.
Related
I have designed a class "Graphs" and have initialized 4 lists to store the values that I fetch from the firebase database. I have created a function "fetch_values" to fetch the values and store them in the respective lists. That part is working perfectly. But when I'm trying to access those updated lists in another function "store_values" inside the same class "Graphs", I am getting an error "NameError: name 'fetch_values' is not defined" This function store_values is supposed to take those lists and save the values in a CSV file in my folder. However, it's not working.
I hope my question is clear, any help would be appreciated!
This is my class:
class Graphs(object):
def fetch_values():
temp=[]
mois=[]
hum=[]
DT=[]
def fetch():
LY_project=firebase.FirebaseApplication("https://ly-project-b1f1c-default-rtdb.firebaseio.com/",None)
result=LY_project.get("Values","")
#time=pd.to_datetime((result["LastIrrD"] +" "+ result["LastIrrT"]),infer_datetime_format=True)
now=dt.datetime.now().strftime("%H:%M:%S")
temp.append(result["Temperature"])
mois.append(result["Moisture"])
hum.append(result["Humidity"])
DT.append(now)
#DT.append(time)
#print(time)
print(len(DT))
print(result)
#-------------------------------------------Start Fetch-------------------------------------------#
print ("Fetching Values...\n")
n=5 #Number of readings
interval=2 #Interval between readings
safety=n # Safely space added to avoid overwriting of values
rt = RepeatedTimer(interval, fetch) # it auto-starts, no need of rt.start()
try:
sleep(n*interval+safety) # your long-running job goes here...
finally:
rt.stop() # try/finally block to make sure the program ends!
print("\nValues fetched successfully.")
return temp,mois,hum,DT
#----------------------------------------------------------------Store the fetched values---------------------------------------------------------------------#
def store_values():
new_DT,new_temp,new_hum,new_mois=fetch_values()
#Save data to csv file
fields = ['Date-Time', 'Soil Moisture', 'Temperature', 'Humidity']
rows = [new_DT, new_mois, new_temp,new_hum]
dict = {'Date-Time': new_DT, 'Soil Moisture': new_mois, 'Temperature': new_temp, "Humidity": new_hum}
df = pd.DataFrame(dict)
display(df)
#df.to_csv("readings4.csv")
The code under "start fetch is working fine and I am able to fetch the values in the lists. However, when I call those lists in the function below that (store_values), I am getting an error."
Please help!
This is the error I am getting:
enter image description here
You should add self keyword to all lists in class functions. Here is an example:
class Dog:
tricks = []
def add_trick(self, trick):
self.tricks.append(trick)
It is good enough to work, but a correct implementation of a class should look like this:
class Dog:
def __init__(self, name):
self.name = name
self.tricks = []
def add_trick(self, trick):
self.tricks.append(trick)
I'm trying to return variable name, but i keep getting this:
<classes.man.man object at (some numbers (as example:0x03BDCA50))>
Below is my code:
from classes.man import man
def competition(guy1, guy2, counter1=0, counter2=0):
.......................
some *ok* manipulations
.......................
if counter1>counter2:
return guy1
bob = man(172, 'green')
bib = man(190, 'brown')
print(competition(bob , bib ))
Epilogue
If anyone want to, explain please what I can write instead of __class__ in example below to get variable name.
def __repr__(self):
return self.__class__.__name__
Anyway, thank you for all of your support
There are different ways to approach your problem.
The simplest I can fathom is if you can change the class man, make it accept an optional name in its __init__ and store it in the instance. This should look like this:
class man:
def __init__(number, color, name="John Doe"):
self.name = name
# rest of your code here
That way in your function you could just do with:
return guy1.name
Additionnally, if you want to go an extra step, you could define a __str__ method in your class man so that when you pass it to str() or print(), it shows the name instead:
# Inside class man
def __str__(self):
return self.name
That way your function could just do:
return guy1
And when you print the return value of your function it actually prints the name.
If you cannot alter class man, here is an extremely convoluted and costly suggestion, that could probably break depending on context:
import inspect
def competition(guy1, guy2, counter1=0, counter2=0):
guy1_name = ""
guy2_name = ""
for name, value in inspect.stack()[-1].frame.f_locals.items():
if value is guy1:
guy1_name = name
elif value is guy2:
guy2_name = name
if counter1 > counter2:
return guy1_name
elif counter2 > counter2:
return guy1_name
else:
return "Noone"
Valentin's answer - the first part of it at least (adding a name attribute to man) - is of course the proper, obvious solution.
Now wrt/ the second part (the inspect.stack hack), it's brittle at best - the "variables names" we're interested in might not necessarily be defined in the first parent frame, and FWIW they could as well just come from a dict etc...
Also, it's definitly not the competition() function's responsability to care about this (don't mix domain layer with presentation layer, thanks), and it's totally useless since the caller code can easily solve this part by itself:
def competition(guy1, guy2, counter1=0, counter2=0):
.......................
some *ok* manipulations
.......................
if counter1>counter2:
return guy1
def main():
bob = man(172, 'green')
bib = man(190, 'brown')
winner = competition(bob, bib)
if winner is bob:
print("bob wins")
elif winner is bib:
print("bib wins")
else:
print("tie!")
Python prints the location of class objects in memory if they are passed to the print() function as default. If you want a prettier output for a class you need to define the __repr__(self) function for that class which should return a string that is printed if an object is passed to print(). Then you can just return guy1
__repr__ is the method that defines the name in your case.
By default it gives you the object type information. If you want to print more apt name then you should override the __repr__ method
Check below code for instance
class class_with_overrided_repr:
def __repr__(self):
return "class_with_overrided_repr"
class class_without_overrided_repr:
pass
x = class_with_overrided_repr()
print x # class_with_overrided_repr
x = class_without_overrided_repr()
print x # <__main__.class_without_overrided_repr instance at 0x7f06002aa368>
Let me know if this what you want?
I am creating a class structure in python for a city, that stores the name, country, population and language for a city, all of which are input by the user. The information shall then be printed.
I think that I may be successful in storing the information within the class structure (although this may be wrong as well), but I am unsuccessful in printing the information. Currently, I am receiving the error that int object is not subscriptable.
class User():
def _init_(self, username, password, email, numOfLogins):
User.username = username
User.password = password
User.email = email
User.numOfLogins = numOfLogins
#User Record Array Creation
def createUserArray(num , User):
UserArray = []
for x in range(num):
UserArray.append(User)
return UserArray
#User Record Array Population
def populateUserArray(num, UserArray):
for x in range(len(userArray)):
UserArray[x].username = str(input("Enter username."))
UserArray[x].password = str(input("Enter password."))
UserArray[x].email = str(input("Enter email address."))
UserArray[x].numOfLogins = int(input("Enter number of logins."))
return UserArray
#User Record Array Display
def displayUserArray(UserArray, num):
for x in range(len(userArray)):
print(UserArray[x].username, UserArray[x].password, UserArray[x].email, str(UserArray[x].numOfLogins))
#Top Level Program
numOfUsers = 3
userArray = createUserArray(numOfUsers, User)
userArray = populateUserArray(numOfUsers, userArray)
displayUserArray(numOfUsers, userArray)
The contents of the class should all be displayed at the end of the program, but at the minute my program crashes due to the error - int object is not subscriptable.
you can always implement the method : __str__(self) of an object , and then when you just print it with :
your_obj = User(...)
print your_obj
your __str__(self) will be called and you can return from it whatever you want to print.
for example:
def __self__(self):
return `this class has the following attributes: %s %s %s %s` % (self.username,self.password,self.email ,self.numOfLogins )
and this what will get print, i think it is more efficient and well coded to work like that and not creating a function that print each class attribute separately.
The cause of your error is quite simple and obvious: you defined the function as displayUserArray(UserArray, num) but call it with displayUserArray(numOfUsers, userArray) - IOW you pass the arguments in the wrong order.
This being said, almost all your code is wrong, you obviously don't get the difference between a class and instance and how to use a class to create instances. I strongly suggest you read at least the official tutorial, and check a couple other tutorial and/or example code on the topic of classes and instances.
Here is Customer class:
class Customer:
def __init__(self, timestamp, cid, item_count):
self.time_stamp = timestamp
self.customer_name = cid
self.item_count = item_count
def checkout(self, new_timestamp):
self.time_stamp = new_timestamp
def get_cus_name(self):
return self.customer_name
If I create an empty list of Customer objects like:
customers = [Customer]
And then somewhere else I try to call Customer methods in a loop like:
def checkout_customer(self, cid):
for cus in self.customers:
if cus.get_cus_name == cid:
cus.checkout(self.cur_num_customers + 7)
why do I get an error when I try to call cus.checkout? My ide tells me that it expects a Customer but got an int. Why doesn't it pass itself into the 'self' arg here?
However if I just create a Customer object and directly call its methods, it works fine:
def foo(self):
cus = Customer(1,'pop',2)
cus.checkout(23)
This is my first time learning python, and ive been stuck trying to figure out lists, and accessing its members. Perhaps my initialization of self.custormers = [Customer] is incorrect?
EDIT:
In my constructor of tester class I create an empty list like this:
self.customer = [Customer]
I am able to add customers no problem:
def add_custormer(self, customer):
self.customers.append(customer)
My problem is not adding customers, but accessing their methods once they are in a list. Doing something like this self.customers[0].checkout(1,'pop',2) gives me an error "Expected type 'Customer' got int".
I am not sure of the class where checkout_customer lives but I am assuming you declare the list self.customers somewhere in it.
self.costumers = []
If you intend to add an element Customer to the list you should use something like: self.customers.append(Customer(x,y,z)) since you want to add a new customer to the list and when doing so you are required to initialize the Customer class.
I didn't try the code but I believe something like this should work:
def foo(self):
self.customers.append(Customer(1,'pop',2))
self.checkout_customers(23)
pI am working on a bit of code that does nothing important, but one of the things I am trying to make it do is call a function from another class, and the class name is pulled out of a list and put into a variable. Mind you I have literally just learned python over the last 2 weeks, and barely know my way around how to program.
What I believe that this should do is when getattr() is called, it will pass the attribute 'run_question' that is contained in the respective class with the same name as what is in question_type, and then pass it onto 'running_question'. I know there are probably better ways to do what I am attempting, but I want to know why this method doesn't work how I think it should.
#! /usr/bin/python
rom random import randrange
class QuestionRunner(object):
def __init__(self):
##initialize score to zero
self.score = 0
##initialize class with the types of questions
self.questiontypes = ['Addition', 'Subtraction', 'Division', 'Multiplication']
##randomly selects question type from self.questiontypes list
def random_type(self):
type = self.questiontypes[randrange(0, 4)]
return type
##question function runner, runs question function from self
def run_questions(self):
try:
question_type = self.random_type()
running_question = getattr(question_type, 'run_question' )
except AttributeError:
print question_type
print "Attribute error:Attribute not found"
else: running_question()
class Question(object):
pass
class Multiplication(Question):
def run_question(self):
print "*"
class Division(Question):
def run_question(self):
print "/"
class Subtraction(Question):
def run_question(self):
print "-"
class Addition(Question):
def run_question(self):
print "+"
test = QuestionRunner()
test.run_questions()
This outputs:
[david#leonid mathtest] :( $ python mathtest.py
Division
Attribute error:Attribute not found
[david#leonid mathtest] :) $
Which indicates that I am not getting the run_question attribute as I expect.
I should note that when I put the functions into the QuestionRunner class in the following way, everything works as expected. The main reason I am using classes where it really isn't needed it to actually get a good grasp of how to make them do what I want.
#! /usr/bin/python
from random import randrange
class QuestionRunner(object):
def __init__(self):
##initialize score to zero
self.score = 0
##initialize class with the types of questions
self.questiontypes = ['addition', 'subtraction', 'division', 'multiplication']
##randomly selects question type from self.questiontypes list
def random_type(self):
type = self.questiontypes[randrange(0, 4)]
return type
##question function runner, runs question function from self
def run_questions(self):
try:
question_type = self.random_type()
running_question = getattr(self, question_type)
except AttributeError:
exit(1)
else: running_question()
def multiplication(self):
print "*"
def division(self):
print "/"
def addition(self):
print "+"
def subtraction(self):
print "-"
test = QuestionRunner()
test.run_questions()
Any help on why this isn't working would be great, and I appreciate it greatly.
Any help on why this isn't working would be great, and I appreciate it greatly.
Ah, I have found out the missing concept that was causing my logic to be faulty. I assumed that I could pass the name of an object to getattr, when in reality I have to pass the object itself.