Arbitrary categorisation - learning decision trees, Computer Engineering

Assignment Help:

Arbitrary categorisation - learning decision trees:

Through visualising  a set of boxes with some balls in. There if all the balls were in a single box so this would be nicely ordered but it would be extremely easy to find a particular ball. Moreover If the balls were distributed amongst the boxes then this would not be so nicely ordered but it might take rather a whereas to find a particular ball. It means if we were going to define a measure based at this notion of purity then we would want to be able to calculate a value for each box based on the number of balls in it so then take the sum of these as the overall measure. Thus we would want to reward two situations: nearly empty boxes as very neat and boxes just with nearly all the balls in as also very neat. However this is the basis for the general entropy measure that is defined follows like: 

Now next here instantly an arbitrary categorisation like C into categories c1, ..., cn and a set of examples, S, for that the proportion of examples in ci is pi, then the entropy of S is as: 

198_Arbitrary categorisation - learning decision trees.png

Here measure satisfies our criteria that is of the -p*log2(p) construction: where p gets close to zero that is the category has only a few examples in it so then the  log(p) becomes a big negative number and the  p  part dominates the calculation then the entropy works out to be nearly zero. However make it sure that entropy calculates the disorder in the data in this low score is good and as it reflects our desire to reward categories with few examples in. Such of similarly if p gets close to 1 then that's the category has most of the examples in so then the  log(p) part gets very close to zero but it  is this that dominates the calculation thus the overall value gets close to zero. Thus we see that both where the category is nearly  -  or completely  -  empty and when the category nearly contains as - or completely contains as  - all the examples and the score for the category gets close to zero that models what we wanted it to. But note that 0*ln(0) is taken to be zero by convention them.


Related Discussions:- Arbitrary categorisation - learning decision trees

Explain floating point arithmetic pipelines, Floating point Arithmetic pipe...

Floating point Arithmetic pipelines Floating point calculations are the best candidates for pipelining. Take the illustration of addition of two floating point numbers. Subsequ

Define the types of software life cycle, Define the types of software life ...

Define the types of software life cycle Any system progress refers to the initial part of the software life cycle: analysis, design, and implementation. During object oriented

Returns the information about tasks running, Returns the information about ...

Returns the information about tasks running int info = pvm_tasks( int where, int *ntask, struct pvmtaskinfo **taskp ) struct pvmtaskinfo {  int ti_tid; int ti_pt

What are simm and dimm, What are SIMM and DIMM? SIMM are Single In-Line...

What are SIMM and DIMM? SIMM are Single In-Line Memory Module. DIMM is Dual In-Line Memory Modules. Such modules are an assembly of various memory chips on a separate small boa

Padovan string, how to write this program,what are the declaration and func...

how to write this program,what are the declaration and function are needed in java program in java // aakash , suraj , prem sasi kumar kamaraj college program 1 : pack

What happens if acknowledge() is called within a transaction, As per the JM...

As per the JMS specification, when you are in a transaction, the acknowledge Mode is ignored. If acknowledge() is known as within a transaction, it is ignored.

client will now send ten integers , Change this program so that every clie...

Change this program so that every client will now send ten integers and receives their sum from the server. In Java, for loops can be easily executed as follows: for (int i = 0 ; i

Illustrate working of magnetic bubble memories, Q. Illustrate working of Ma...

Q. Illustrate working of Magnetic Bubble Memories? In many materials like garnets on applying magnetic fields certain cylindrical areas whose direction of magnetization is oppo

Structure of 8086 cpu, 8086 microprocessor comprises two independent units:...

8086 microprocessor comprises two independent units:  1.  Bus Interface unit 2.  Execution unit Please refer to Figure below. Figure: The CPU of INTEL 8086 Microp

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd