Calculate average heights from data in file

Question

**Goal: Print out average heights and amount of people are in the file(By counting the names) and ask for new input from user, then calculate the new average height **

Problem: There's no output it just outputs "Process finished with exit code 0" the output should be "Enter Your name : "

Here's the code:

class Calutis:
    def init(self):
        self.names=[]
        self.heights=[]
        self.totalheight=0
        self.totalcount=0

    def reset(self):
        self.names = []
        self.heights = []
        self.totalheight = 0
        self.totalcount = 0

    def calAvgHeight(self):
        f=open("listOfStudentHeight.txt","r")
        for line in f:
            info=line.split("\t")
            self.names.append(info[0])
            self.heights.append(float(info[1]))
            self.totalheight+=float(info[1])
            self.totalcount=len(self.names)
            print("the average score of " + self.totalcount + "students is: " + (self.totalheight)/self.totalcount)

    def adduser(self):
        self.names=input("Enter Your Name : ")
        while(True):
            try:
                self.heights=round(float(input("Enter Your Height in Metres")),2)
                break
            except ValueError:
                print("Enter a valid input for height: ")
            try:
                self.names=(str(input("Enter Your Name : ")))
                break
            except ValueError:
                print("Enter a valid input for name : ")

        f=open("listOfStudentHeight.txt",'a')
        f.write(self.names + "\t" + self.heights + "\n")
        f.close()

        calBox = Calutis()
        calBox.adduser()
        calBox.calAvgHeight()

This is the weights and names file content:
CHITRA DEVI D/O SILVARAJAH  1.65
MARSHEAL HOUDEL S/O MATHEWS JA  1.72
MUHAMMAD AZLIE B ZULKIFLIE  1.68
HO QIN YUAN Melvin  1.69
TENG YONG PENG DESMOND  1.76
CHEONG LEE YEE  1.59
MUHAMMAD ZULFIKAR B ZAINAL  1.9
ASYRAFIZWANI BTE ABDUL LATIFF   1.58
HIE BAO XIN 1.63
MAK YU JIE  1.67

Please consider lending me a helping hand, Any help will be greatly appreciated !

Answer 1

Here are a couple things you need to do

1. Instantiate the class: calculator = Cal()
2. Call the adduser function: calculator.addusers()
3. Call the caluser function: calculator.caluser()

The class definition is not running code. Think of it like a resource that has functionality you can access and call.

Also, is all this in one file? If this class definition is in a separate file, make sure you are actually running the file that contains the 3 lines I mentioned.

Closing the file should not affect the functionality of your code, but it is good practice. After you are done writing to a file, you should call file.close(). As to the specifics of why, it's a more advanced operating systems topic related to file descriptors.

Answer 2

Issue

Your code doesn't appear to have any outputs because the code isn't actually doing anything! :P Specifically, even though you wrote a bunch of lines of code, none of them are actually getting executed.

Explanation

You defined a class called Cal, but you aren't actually using it. A class is like a pre-filled box in that it is a container that holds many useful things, namely functions and variables. The items in the box don't do anything while sitting there - you must actively open the box and grab those items in order to use them. Regarding what this means for writing Python code, you must actually access that class and use its functions/variables in order to do anything with it.

There's another layer here. Writing up a class (like your Cal class) only defines what the pre-filled box looks like. It doesn't actually create the pre-filled box. So maybe a more accurate description of what a class is would be a "blueprint" for a pre-filled box.

Solution

You have to do three things to get any of the code in your class Cal to run:

1. Define a blueprint for your box (you've already done this by creating class Cal)

This is known as "creating a class definition" or "defining a class"

2. Create an instance of the box from the "blueprint"

This is known as "creating an instance of a class" or "instantiating a class". The thing that you create is known as an "object" (I know, not as fun as a box haha).

3. Reach into the box, grab something, and use it

You must access the functions or member variables within a class in order to use them.

Here's how you do these 3 things...

# Step 1: Create the blueprint
# Put your class definition for "Cal" here
#

calBox = Cal()  # Step 2: Create the box (note: parentheses are important here!)
calBox.adduser()  # Step 3: Use something from the box (eg: call one of your functions!)

And as it turns out, your "blueprint" can be used to create many boxes! So you can have 3, 4, 5... however many you want :)

calBox1 = Cal()  # Create a box (i.e. an instance of the Cal class)
calBox2 = Cal()  # Create another box (i.e. another instance)
calBox3 = Cal()  # Create anotherrrr box :P

That's it! Add those two lines of code below and outside of your Cal class definition. Then you should see some output! :)