Python functions with dots

Question

I have defined a of ordered pairs called f and defined a function applyfunction that goes through the ordered pairs looking at the first value to compare and when it does match to print the second value.

f = {(1,2),(2,4),(3,6),(4,8)}


def applyfunction (f,x):
    for xy in f:
        if xy[0]==x:
            print(xy[1])


applyfunction(f,3)

The above works just the way I want it to. In the meantime I have seen that in python there are functions that have a dot notation and I think that would be useful here. So my question, how can I rewrite the applyfunction definition such that I can use the following notation: f.applyfunction(3)?

Those are called methods. They are class attributes. When invoked through a class instance, they become bound methods, with the first argument bound to the class instance. So your question is, "Would defining a class help my application?" — Tom Karzes
– Tom Karzes, Commented Aug 22, 2020 at 8:59
I think you're asking how you can add the applyfunction function as a method to sets. Don't do that, just use the function. — jonrsharpe
– jonrsharpe, Commented Aug 22, 2020 at 8:59
@jonrsharpe I only want this is a one off way to show the idea of going from a set of ordered pairs to a function. — Geoff
– Geoff, Commented Aug 22, 2020 at 9:01

Andreas · Accepted Answer · 2020-08-22 09:07:04Z

2

You can wrap the ordered pairs into a class of your own, which has the method (method == a function inside a class) you mentioned inside of it.

class OrderedPairWrapper():
    
    def __init__(self, op):
        self.op = op
    
    def applyfunction (self, x):
        for xy in self.op:
            if xy[0]==x:
                print(xy[1])

f = {(1,2),(2,4),(3,6),(4,8)}
f = OrderedPairWrapper(f)

print(f.applyfunction(3))
# 6

answered Aug 22, 2020 at 9:07

Andreas

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2 Comments

jonrsharpe Over a year ago

Note that this sort of thing ("two methods, one of which is __init__") is canonically when to stop writing classes.

Andreas Over a year ago

@jonrsharpe I think so too, but I also think he just wanted an example to get his head around this dot methods in the first place.

Sanmitha Sadhishkumar · Accepted Answer · 2020-08-22 10:35:44Z

1

Dots are used to access methods of a class using its object name. If you want to access that using dot operator, create an object called f for a class with a method applyfunction. Then you can accomplish your desired task

answered Aug 22, 2020 at 10:35

Sanmitha Sadhishkumar

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