Python help

[charsan]

Hi all,

If anyone knows Python I could use some help. I need to make a class that takes user input to add numbers to a list then sum the numbers so if the user enters 1, 2, and 3 the sum of 3 + 2 + 1 would be 6, than I have to reverse the list (I know there is a reverse function) and finally show the list as entered.

I can do this:

Converting the three-digit number to a string to get each individual character. You should use modulus and divide.

I can't:
print in any method of the class
Using input in any method of the class.

I am totally lost. If anyone can help I would so greatful

 

[Gregory Thompson]

I don't know. But this link might help.

BeginnersGuide/Programmers - Python Wiki

 

[charsan]

Thank you

 

[Occams Barber]

Hi all,

If anyone knows Python I could use some help. I need to make a class that takes user input to add numbers to a list then sum the numbers so if the user enters 1, 2, and 3 the sum of 3 + 2 + 1 would be 6, than I have to reverse the list (I know there is a reverse function) and finally show the list as entered.

I can do this:

Converting the three-digit number to a string to get each individual character. You should use modulus and divide.

I can't:
print in any method of the class
Using input in any method of the class.

I am totally lost. If anyone can help I would so greatful

I found this under 'Python Help' on Google

Don't thank me - You're welcome

OB

 

[Tanj]

Hi all,

If anyone knows Python I could use some help. I need to make a class that takes user input to add numbers to a list then sum the numbers so if the user enters 1, 2, and 3 the sum of 3 + 2 + 1 would be 6, than I have to reverse the list (I know there is a reverse function) and finally show the list as entered.

I can do this:

Converting the three-digit number to a string to get each individual character. You should use modulus and divide.

I can't:
print in any method of the class
Using input in any method of the class.

I am totally lost. If anyone can help I would so greatful

I have 30 years of python programming experience, but I'm not sure what the problem is. What do you mean you can't print in any method of the class, or "using input in any method of the class"

Might help if you posted the code.

 

[charsan]

I have 30 years of python programming experience, but I'm not sure what the problem is. What do you mean you can't print in any method of the class, or "using input in any method of the class"

Might help if you posted the code.

Well that was what the assignment said, that I can't have the user input inside the method, I have to have it for a lack of a better word in the main part of the program. Does that make sense?

Assignment 1. Console Application
For this assignment you are to create a class called Lab1. Inside the class you will create three methods that will modify a three-digit whole number:

sumNums - This method takes as input a three digit int and returns the sum of the three numbers. For instance, 123 would return 6 because 3 + 2 + 1 is 6

reverseNums - This method takes as input a three digit whole number and returns the number in reverse as a String. For instance, 123 would return "321"

getList - This method takes as an argument a three digit whole number and returns the numbers as an int list. Each element of the list should contain one of the numbers

In the main method prompt for a three digit number to be input.

1. Create an instance of the Lab1 class
2. Call the sumNums method passing to it the whole number that was input into the Console window
3. Call the reverseNums method passing to it the whole number that was input into the Console window.
4. Call the getList method passing the whole number that was input at the Console window. Print the list out one number per line from the Main method using a for loop.

Note:

You can use a for loop to iterate through a list as follows:

myList = [2,4,6,8,10]

for nums in myList:
print(nums)

Your output should be the sum of the digits, the whole number in reverse order as a String, and the int as a list.

Your output should resemble the following:

Things to Review

• for loops
• counted loops with while
• lists
• Value producing methods

Things that will cost you points

• Converting the three-digit number to a string to get each individual character. You should use modulus and divide.
• print in any method of the class
• Using input in any method of the class.

I posted the assignment now. It's been 19 years since I took python 1 and I don't understand classes. Now I even studied "Learn Python the hard way" and get everything but I don't understand classes. Like I need to make a list where I take input from the user so I think something like this, by the way I have two files:

File one - Lab1.py
class Lab1 :
def __init__(self, myList) :
self.setmyList = newList = []

File 2 - Assingment1.py
from Lab1 import Lab1

#here I am not sure if this is right
lis = newList(int(input("Enter a number: ")))

This does not look right, I think I bungled it typing here

 

[Tanj]

Well that was what the assignment said, that I can't have the user input inside the method, I have to have it for a lack of a better word in the main part of the program. Does that make sense?



I posted the assignment now. It's been 19 years since I took python 1 and I don't understand classes. Now I even studied "Learn Python the hard way" and get everything but I don't understand classes. Like I need to make a list where I take input from the user so I think something like this, by the way I have two files:

File one - Lab1.py
class Lab1 :
def __init__(self, myList) :
self.setmyList = newList = []

File 2 - Assingment1.py
from Lab1 import Lab1

#here I am not sure if this is right
lis = newList(int(input("Enter a number: ")))

This does not look right, I think I bungled it typing here

Well, firstly might I say that's a really silly usage of classes...but that's not your fault. Anyway, I suspect from the instructions what they are saying is that the input and print stuff needs to be in the main function, not the class. In other words

DONT DO THIS:

class Lab1:
...def someMethod(self):
......input
......print


DO THIS

class Lab1:
...def __init__(self,x):
......self.rawData = int(x)

...def sumNums(self):
......Do some logic processing here
......return sumNumsResult

......

def main:
...x = input('Please enter the 3 digit number')
...myObj = Lab1(x)
...print(myObj.sumNums())

 

[Tanj]

@charsan

The modulus directive means you have to split the number using math rather than string processing.

It's really easy with a string
x = '123'
mylist = [x[0:1],x[1:2],x[2:3]]

However with a number you will need to do something like:
x = int('123')
firstDigit = x/100
x = x % 100 # note % is the python modulo command, asking for the remainder of the division. In this case it will return 23, because 123/100 has 23 as the remainder
secondDigit = x/10
thirdDigit = x % 10
numList = [firstDigit,secondDigit,thirdDigit]

 

[Tanj]

@charsan

Finally, regards classes and object-oriented (OO) programming, these are are a truly excellent technique for ensuring scalable, reusable, readable code. The way to think about it is in terms of objects rather than functions.

Consider a library. From a functional programming perspective you might do something like

def checkOutABoot(bookId)

The problem is what if I want to know something about the book apart from it's ID? I'd then need
def getTheTitleSomehow(bookId)

On the other hand, if I build a Book object, I can then decorate that object with all the information the book knows about itself
book.authors
book.title
book.isdnNumber
etc

So I can handily pass the book object around my code and know all of the stuff the book knows about itself is easily found and in one place.

In OO, functions on classes are called methods, and variables on classes are called properties.

 

[charsan]

Thank you very, very much @Tanj it helps a lot.

 

[charsan]

Hi @Tanj sorry to bother you again. This is what I have worked on so far in two files:

class Lab1:
def __init__(self, x, myList):
self.rawData = int(x)
self.Data = myList() # putting data into a list
def sumNums(self):
sum(x)
return sumNums

In the other file

from Lab1 import Lab1

x = int(input("Please enter an 3 digit number: "))
myObj = Lab1(x)
print(myObj.sumNums)

Now in the class file it doesn't like x in the sum(x) but maybe I am on the right track

 

[Tanj]

Hi @Tanj sorry to bother you again. This is what I have worked on so far in two files:

class Lab1:
def __init__(self, x, myList):
self.rawData = int(x)
self.Data = myList() # putting data into a list
def sumNums(self):
sum(x)
return sumNums

In the other file

from Lab1 import Lab1

x = int(input("Please enter an 3 digit number: "))
myObj = Lab1(x)
print(myObj.sumNums)

Now in the class file it doesn't like x in the sum(x) but maybe I am on the right track

1)
You are using myList in correctly. In the init you are passing it in as a parameter but then in the code calling it as a function.

2) The reason it doesn't like the x in sumNums is because it has no idea what you are talking about. x doesn't exist in the scope of that function. To access properties they need to be set and get with self.

3) Any variables evaporate when the function finishes. In my example below, when init finishes, d1, d2, d3, and temp cease to exist, even though the values that were represented by d1,d2,d3 have been persisted in self.myList.

class Lab1:
...def __init__(self,data):
......self.rawData = int(data)
......d1 = self.rawData/100
......temp = self.rawData % 100
......d2 = temp/10
......d3 = temp % 10
......self.myList = [d1,d2,d3]

...def sumNums(self):
......result = sum(self.myList)
......return result


In the other file

from Lab1 import Lab1
x = input("Please enter an 3 digit number: ")
myObj = Lab1(x)
print(myObj.sumNums())

 

[charsan]

Thank you again, I really am grateful.