Structured data, Python Programming

Structured data

We will often  want  to work  with  large  groups of data.   Rather  than  providing  each  number its own  value,  we need  to manage the data  into natural structures: grocery  lists, matrices, groups of employee medical records. We will explain  a simple  but  enormously useful  and ?exible list, which is conveniently create into Python: the list. The precise information  of how lists are shown inside a computer vary from language to language. We will take an abstract model  in which we think of a list as an ordered sequence of memory locations that numbers. So, for example, in Python, we may show a list of three integers as:

 

644_structured data.png

 

 

Now that we have lists, we have some new kinds  of statements, which let us extract elements of a list by specifying their indices.   An index  of 0 related to the ?rst  element of a list.  An index  of -1 related to the last element So, if a is bound as above, then we would have:

 

>>> a[0]

>>> a[2] 

>>> a[-1] 

>>> a[3] 

 

Traceback (most recent call last): File "", line 1, in IndexError: list index out of range.Note that if we attempt to access an element of the list that is not present, then a exception is generated.

 

 

847_structured data  2.png

 

 

It is also possible  to have  an empty list, which  is given in Python as []. We will show it in our memory diagrams as a short box. So example, this list  looks like this in memory:

>>> z = [3, [], [[]]]

 

 

 

515_structured data  3.png

 

Python has a useful method, len, which takes a list as an argument and gives its size. It does not look inside  the elements of the list-it just returns the number of elements at the top level of list. So, we take

 

>>> len([1, 2, 3])

3

>>> len([[1, 2, 3]])

1

 

Posted Date: 8/11/2012 1:38:38 AM | Location : United States







Related Discussions:- Structured data, Assignment Help, Ask Question on Structured data, Get Answer, Expert's Help, Structured data Discussions

Write discussion on Structured data
Your posts are moderated
Related Questions
Tower of Hanoi game that you can let a player to move discs between the towers using a mouse. Moreover, you are required to do the followings: •Graphically represent any state in t

how to calculate standard deviations in programming

Tuples  and strings Python has two different more list-like data  types  that are very important to understand.A tuple  is a structure that  is like a list, but  is not  mutab

Coding examples Following are some  attempts at defining a function isSubset,  which  takes  two  arguments, a and  b, and  returns True if a is a subset  of b, assuming that

Your task is to construct a translator from the subset of Python in Project 3 intocontinuation-passing style (CPS). Of course, the expected way of accomplishing this is to trans

given number isprime number or not


Booleans   Before we talk about  conditionals, we require  to clarify the Boolean  data  type.  It has two values False and True. Typical statement that have Boolean values

Procedure calls When you compute an expression of the form ( ,  ..., )   the Python interpreter treats  this as a procedure call. It will be simpler to talk about

1 Low Level Exploits 1.1 Savegames Jimmy is becoming increasingly frustrated at the computer game hes playing. He has a save right before the levels boss but he needs either more