Stack implementation in python using jupyter

Question 1

This is my first program in Python: a stack implementation.

class Stack:    items =[];    index =-1;    def isEmpty(self):        return  self.index >=0;    def push(self,item):            self.index  +=1;            print(self.index);            self.items.insert(self.index,item);    def pop(self):        if self.index<0:            raise Exception(" no items in list");        else:                del self.items[self.index];            self.index -=1;    def peek(self):        print(self.index);        if self.index >-1:            return self.items[self.index];stackobj = Stack();stackobj.push("solomon");stackobj.push("helloworld")stackobj.pop();print(stackobj.peek())

Even though this program works I'm still confused as to whether I've written the program in the right way. I am also not sure when to use theself operator.

Question 2

Welcome to the land of Python!

If you come from Java, think asself being the same asthis in Java.It is a reference to the object, the difference being in Python, you have to explicitly pass self as a parameter to the class methods.

If you write in Java

class Stack{    //constructor and class variables goes here    void pop(){       if(this.index < 0)       //logic of the function goes here    }}

In Python you write like you did here

class Stack:    # constructor and class variables goes here    def pop(self):        if self.index<0:        # logic of the function goes here

You see thatself andthis serve the same purpose.

An another point, you should use documentation! As inPEP257 the format recommanded is like:

def complex(real=0.0, imag=0.0):    """Form a complex number.    Keyword arguments:    real -- the real part (default 0.0)    imag -- the imaginary part (default 0.0)    """    if imag == 0.0 and real == 0.0:        return complex_zero    ...        '''

Another thing, to followPEP8 it is better to write assignment and condition with a space after the operator.Writeitems = [] orself.index >= 0 instead ofitems =[] orself.index >=0.

Also you can drop; in Python, it's not Java :)

Edit: Also look at @Jon's comments below

Question 3

Some other things,items should be an instance attribute and not a class one,index is redundant as you can dolen(items) and then you're not manually carrying it about somewhere else, and thepop might as well useitems.pop(0) and optionally catch the exception and raise a more meaningful one - raisingException is fairly broad...peek also doesn't seem to mirror its behaviour and returnsNone. Also -if items is sufficient for an empty check - no need to check its length there.

Question 4

Some very good points!

Question 5

(and.append instead of.insert) :)

Julien Rousé 8619 silver badges20 bronze badges · Answer 1 · 2018-01-20 15:50:47Z

Welcome to the land of Python!

If you come from Java, think asself being the same asthis in Java.It is a reference to the object, the difference being in Python, you have to explicitly pass self as a parameter to the class methods.

If you write in Java

class Stack{    //constructor and class variables goes here    void pop(){       if(this.index < 0)       //logic of the function goes here    }}

In Python you write like you did here

class Stack:    # constructor and class variables goes here    def pop(self):        if self.index<0:        # logic of the function goes here

You see thatself andthis serve the same purpose.

An another point, you should use documentation! As inPEP257 the format recommanded is like:

def complex(real=0.0, imag=0.0):    """Form a complex number.    Keyword arguments:    real -- the real part (default 0.0)    imag -- the imaginary part (default 0.0)    """    if imag == 0.0 and real == 0.0:        return complex_zero    ...        '''

Another thing, to followPEP8 it is better to write assignment and condition with a space after the operator.Writeitems = [] orself.index >= 0 instead ofitems =[] orself.index >=0.

Also you can drop; in Python, it's not Java :)

Edit: Also look at @Jon's comments below

Some other things,items should be an instance attribute and not a class one,index is redundant as you can dolen(items) and then you're not manually carrying it about somewhere else, and thepop might as well useitems.pop(0) and optionally catch the exception and raise a more meaningful one - raisingException is fairly broad...peek also doesn't seem to mirror its behaviour and returnsNone. Also -if items is sufficient for an empty check - no need to check its length there.

Movatterモバイル変換

Stack Exchange Network

Stack implementation in python using jupyter

1 Answer1

You mustlog in to answer this question.

Related

Hot Network Questions

Subscribe to RSS