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

Cg transformations, magnify a triangle a(0,0), b(1,1), c(5,2) twice its siz...

magnify a triangle a(0,0), b(1,1), c(5,2) twice its size hile keeping c as fix

What are the structural notations, What are the Structural Notations Th...

What are the Structural Notations These notations comprise static elements of a model. They are considered as nouns of UML model that could be conceptual or physical. Their ele

#title.sequential circuit, design modulo 12 up synchronous counter using t ...

design modulo 12 up synchronous counter using t flip flop

When is a memory unit called as ram, When is a memory unit called as RAM? ...

When is a memory unit called as RAM? A memory unit is called as RAM if any location can be accessed for a read or writes operation in some fixed quantity of time that is indepe

Spatial domain interpolation, Transfer Domain Create an interpolation al...

Transfer Domain Create an interpolation algorithm using the fast Fourier transformer. Assess the performance of the algorithm by using the PSNR and SSIM.  Compare your results w

Smtp vs esmtp, what shortcomings of smtp are over come by esmtp?

what shortcomings of smtp are over come by esmtp?

Find the physical address of instruction, Q. Find the Physical address of i...

Q. Find the Physical address of instruction? Value of Instruction Pointer and holding address of instruction = 1234h Value of code segment register (CS) = 448Ah Physical

Design of structure chart, Design of structure chart - Standard qualit...

Design of structure chart - Standard quality structure charts result in programs that are modular, reusable and simple to execute. - Measures include: Cohesion

Information technology infrastructure, The IT infrastructure of MobTex is s...

The IT infrastructure of MobTex is simple but vital to the operation of the business. All client data, billing, stock management etc is done via a specialised application called "A

Explain 32 to 1 multiplexer tree, Why is Multiplexer Tree needed? Draw ...

Why is Multiplexer Tree needed? Draw the block diagram of a 32:1 Multiplexer Tree and explain how input is directed to the output in this system. Ans. One of the possible

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