How do I update an initialized variable used in Python Class?

Question

I have a class with a list. I am trying to return the list in a different class, but it returns the list as the original empty list instead of the new list with elements (SOLVED!!).

class Whatever:
    def __init__(self,thing):
        self.list=[]
        self.thing=thing

    def list_append(self):
        df1=pd.read_csv('job.py')
        df2=pd.read_csv('home.py')
        self.list.append([df1,df2])
        return self.list
    def new_function(self):
        return self.list

function=Whatever('thing1')
function_output=function.new_function()
print(function_output)

This code never calls list_append(), so of course self.list is still in its original empty state. — John Gordon
– John Gordon, Commented Nov 25, 2019 at 22:25
I am trying to send the results of the list_append() function to the new_function(). I dont exactly know how to do this. — Nick
– Nick, Commented Nov 25, 2019 at 22:29
@NickBosio You need to call a function for it to run to get results from it. — Carcigenicate
– Carcigenicate, Commented Nov 25, 2019 at 22:31
I don't understand what you mean by "I am trying to send the results of the list_append() function to the new_function()", because looking at the code, I can see that list_append() is never called. — John Gordon
– John Gordon, Commented Nov 25, 2019 at 22:35

codrelphi · Accepted Answer · 2019-11-25 22:32:27Z

1

There are many errors in your code:

First, you should write def __init__(self, thing1): instead of def __init__:
You have to call the method list_append() to fill your list.

Here is the working code:

class Whatever:
    def __init__(self, thing1):
        self.list=[]
        self.thing=thing1

    def list_append(self):
        df1=pd.read_csv('job.py')
        df2=pd.read_csv('home.py')

        self.list.append([df1,df2])
        return self.list

    def new_function(self):
        self.list_append() # to call the above method
        return self.list

function=Whatever(thing1)
function_output=function.new_function()
print(function_output)

Test: Let assume df1 = "hello", df2 = "world" and thing1 = "good". The above code will produce the result [['hello', 'world']].

answered Nov 25, 2019 at 22:32

codrelphi

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1 Comment

Nick Over a year ago

Thanks! It works now, but what if I want to loop through self.list. For some reason, my loop output still gives me a list instead of a dataframe. I am going to re-edit my code to show what I am trying to do.

Mechatrnk · Accepted Answer · 2019-11-25 22:33:05Z

0

You are not calling it in a different class but in a different method, but this may be just a terminology error, so nothing serious. But the most important error will probably be this:

You are trying to call output of the list_append function, but you never call it, so you have to do in the new function something like this:

def function(foo):
    return(foo)

def new_function(foo_foo):
    function(foo)

edited Nov 25, 2019 at 22:33

answered Nov 25, 2019 at 22:29

Mechatrnk

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2 Comments

Nick Over a year ago

Lol. Ignore the __init__(self) portion. I thought the return self.output of a method can be used throughout the code.

Mechatrnk Over a year ago

Sorry, my mistake, I tried to help but then I realized I am writing nonsense, my apologies, I deleted the rubbish part

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