Novel text categorization by amalgamation of augmented k nearest neighbourhoodclassification and k-medoids clustering

International Journal of Computational Science and Information Technology (IJCSITY) Vol.1, No.4, November 2013

NOVEL TEXT CATEGORIZATION BY
AMALGAMATION OF AUGMENTED K-NEAREST
NEIGHBOURHOODCLASSIFICATION AND
K-MEDOIDS CLUSTERING
RamachandraRao Kurada1, Dr. K Karteeka Pavan2, M Rajeswari3 and
M Lakshmi Kamala3
1

Research Scholar (Part-time), AcharyaNagarjuna University, Guntur
Assistant Professor, Department of Computer Applications
Shri Vishnu Engineering College for Women, Bhimavaram
2
Professor, Department of Information Technology
RVR & JC College of Engineering, Guntur
3
Department of Computer Applications
Shri Vishnu Engineering College for Women, Bhimavaram

Abstract
Machine learning for text classification is the underpinning of document cataloging, news filtering,
document steering and exemplification. In text mining realm, effective feature selection is significant to
make the learning task more accurate and competent. One of the traditional lazy text classifier k-Nearest
Neighborhood (kNN) has a major pitfall in calculating the similarity between all the objects in training and
testing sets, there by leads to exaggeration of both computational complexity of the algorithm and massive
consumption of main memory. To diminish these shortcomings in viewpoint of a data-mining practitioner
an amalgamative technique is proposed in this paper using a novel restructured version of kNN called
AugmentedkNN(AkNN) and k-Medoids(kMdd) clustering.The proposed work comprises preprocesses on the
initial training set by imposing attribute feature selection for reduction of high dimensionality, also it
detects and excludes the high-fliers samples in the initial training set and restructures a constrictedtraining
set. The kMdd clustering algorithm generates the cluster centers (as interior objects) for each category and
restructures the constricted training set with centroids. This technique is amalgamated with AkNNclassifier
that was prearranged with text mining similarity measures. Eventually, significantweights and ranks were
assigned to each object in the new training set based upon their accessory towards the object in testing set.
Experiments conducted on Reuters-21578 a UCI benchmark text mining data set, and comparisons with
traditional kNNclassifier designates the referredmethod yieldspreeminentrecitalin both clustering and
classification.

Keywords
Data mining, Dimension reduction, high-fliers, k-Nearest Neighborhood, k-Medoids, Text classification

1. Introduction
Pattern recognition concord with bestowing categories to samples, are declared by a set of
procedures alleged as features or characteristics. Despite of prolific investigations in the past
decannary, and contemporary hypothesis with extemporized thoughts, suspicion and speculation
DOI : 10.5121/ijcsity.2013.1406

81


that exists, pattern recognition is facing confront in resolving real world problems [1].There are
two major types of pattern recognition problemscalled unsupervised and supervised. In
classification or the supervised learning, each sample in the dataset appears with a pre-designated
category label, where as in clustering or the unsupervised learning, there is no pre-designated
category label and assemblage is done based on similarities. In this paper, a combinational
learningapproach using classification and clustering is projected for the recognition of text
classifier accuracy and adequacy in judgment.
With the growth of the internet, efficient and accurate Information Retrieval (IR) systems [2]are
of great importance. The present day search engines are able to accomplish enormous amount of
data concerned in Exabyte’s. Text classification effort involuntarily to decide whether adocument
or part of a document has exacting distinctivenesstypically predestined on whether the
documentenclose aconvinced type of topic or not. Uniquely, the topic of fascination is not defined
absolutely or more accurately by the users and as a substitute they are arranged with a set of
documents that comprise the enthrallment of both (positive and negative training set). The
decision-making procedure [3] despotically hauls out the features of text documents and helps to
discriminate positive from negatives. It also administers those appearances inevitably to sample
documents with the help of text classification systems. The k-nearest neighbor rule is a simple
and effective classifier for document classification. In this technique, a document is fashionable
into an exacting category if the category has utmost diversity pertaining to the k nearest neighbors
of the documents in the training set. The k nearest neighbors of a test document isordered based
on their content similarity with the documents in the training set.
This paper probes and recognizes the payback of amalgamation of clustering and classification
for text categorization. This paper is prearranged as follows: Section 2 gives an abrupt analysis of
antecedent works on text classification. Section 3 is devoted to present the proposed approach for
document classification. In Section 4 extensive experimental evaluation on text corpus derived
from the Reuters-21578, a real time data set is summarized and analyzed. The resulting text
categorization rates are comparing favorably for the referred methods with those of the standard
method. Finally, conclusion is drawn and future research directions are identified in Section 5.

2. Literature Survey
TM Cover and PE Hart first proposed an elementary and straightforward classification method
called the K-Nearest Neighbor (kNN) [4], where no former awareness about the circulation of the
data is needed and neighborhood estimation was based on k value.kNN is a non-parametric lazy
learning algorithm, since it does not make any postulations on the original data allocation and
there is no precise training phase to do any simplification over the data points. The fascination of
kNNdominion was of disunion in its minimal training phase and a lavish testing phase.
Few topological methods that pilot to the current state-of-the-are wKNNmethod intended by
TBaileyand AK Jain [5] is aimproved version of simple kNN, assigns weights to training points
according to the distance from centroid. Outliers in the training set that do not affect the mean
point of training set are purged in the work of GW Gates [6], thus reduce the reorganization rate
of sample in large datasets. One of the major pitfall of kNN i.e. memory limitation was addressed
by Angiulli[7], by eliminating data sets which show similarity in training set.Guo and Bell in
[8]proposed a model to automatic reorganize the k value in dynamic web pages of large web
repositories. Automatic classification of data points in training set based on k value was a
research finding of G Guo.In 2003 SC Baguai and K Pal assigned rank to training data for each
category by using Gaussian distribution, thus it dominated the other variations of kNN[9].
Modified kNN[10] suggested by Parvin et.al in 2008 used weights and validity of data points to
classify nearest neighbor and used various outlier elimination techniques. In the year, 2009 Zeng
et.al planned a novel idea for kNN by using n-1 classes to the entire training to address the
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computational complexity [11]. The annoyed paper for this publication was of Z Youg work i.e.
clusters formation using k nearest neighbors in text mining domains [12], proved as a robust
method and overcome the defects of uneven distribution of training set.
Hubert et.al in 2013 composed an algorithm for correspondence search in the metric space of
measure allocation in the thesaurus [13].In 2013, Du et.al proposed an effective strategy to
accelerate the standard kNN, based on a simple principle: usually, nearer points in space are also,
near when they areprojected into a direction, which is used to remove irrelevant points and
decreases the computation cost[14].Basu et.al in 2013 assigned a document to a predefined class
for a large value of k when the margin of majority voting is one or when a tie occurs. The
majority voting method discriminates the criterion to prune the actual search space of the test
document. This rule has enhanced the confidence of the voting process and it makes no prior
assumption about the number of nearest neighbors[15]. One of the major drawbacks of k-Means
clustering technique is its insightfulness to high-fliers; because it’s mean value can be simply
prejudiced by exterior values. The other partitioned clustering technique k-Medoids clustering
which is a disparity of k-Means is more robust to noises and able-bodied to high-fliers. KMedoids clustering is symbolized with an actual point as the center of the cluster instead of a
mean point. The actual point is assumed as a cluster center, if it is located centrally and with
minimum sum of distances to other points [16].

Figure 1. Roadmap of the amalgamative technique for text categorization

3. Proposed Work
The intuition of proposed algorithm operates in three niches. The first niche initiates the
preprocessing on text mining corpus settled in the form of training set. This is accomplished by
attribute feature selection to alienate the higher dimensions of training set and derive a constricted
training set with minimal dimensions. The second niche uses the partitioned clustering kMedoidsalgorithm to define k objects as a most centrally located points in the classes of
constricted training set. A Solemnity model is designed to identify the cluster centers using edit
distance as a similarity measure for each category in the training set. The worthiness of
constricted training set is ensured by high-fliers identification and elimination. The final niche is
embedded exclusively with an accurate text classification system using a novel augmentedkNN
classifier with cosine text mining similarity measure, thus enhances the confidence of assigning a
test sample to a trained categorical class. This insight the text classifier criterion to assign
83


considerable weights to each object in the new constricted training set base upon their minimal
average dissimilarity with the latest computed centroids. It was proven from the results attained
that, the amalgamation of all the three niches rationale a better solution for evaluating the
effectiveness of the text classification. The overview of the proposed intuition is outlined as
figure 1 roadmap of the amalgamative technique for text categorization.

3.1.First Niche – Preprocessing of Text Corpus:
The preprocessing of text classification over datasets includes many key technologies before
extracting the features from the text.The data cleaning process involves removing formatting,
converting the data into plain text, segmentation on sentence, stemming [17], removing
whitespace, uppercase characters, stop words removal [18] and weight calculation.The text
classification is made simpler by eradication of inappropriate dimensions in the dataset. This was
defensible by dispensation of the curse of dimensionality [19] i.e. higher dimensional data sets are
reduced into lower dimensional data set without significant loss of information. In
general,attribute feature selection methods are used to rank each latent feature according to a
fastidious feature selection metric, and then engage the best k features. Ranking entails counting
the incidence of each feature in training set as either positive or negative samples discretely, and
then computing a function to each these classes.
3.1.1.Feature selection
Feature selection methods only selects as subset of meaningful or useful dimensions specific to
applications from the original set of dimensions. The text mining domain, attribute feature
selection methods include Document Frequency (DF), Term Frequency (TF), Inverse Document
Frequency (IDF) etc. These methods fort requisites based on numerical procedures computed for
each document in the text corpus.
The documents in the proposed work use the vector space model to represent document objects.
*
+
Each document is symbolized by a vector in the term space such that
where
is the TF of the term in the document. To represent every document with
the same set of terms, extractingall the terms found in the documents and use them, as the
generated feature vector is necessary. The other method used was the combination of term
frequency with inverse document frequency (TF-IDF). The document frequency
is the number
of documents in anassortment of
documents in which the term transpires. Usually IDF is
given as
. ⁄ /. The weight of a term
in a document is given by
. ⁄ / , -. To maintain theseattribute feature vector dimensionssensible, only
terms with the maximum weights in all the documents are selected as n features. TF-IDF is
(
)
( )
(
), where is the terms in document and is
termed as
the total number of documents in D.
Stemming [21]refers to the process of erasing word suffixes to retrieve the root (or stem) of the
words, which reduces the complexity of the data without significant loss of information in a bag
ofwords representing the text data. An attractive alternative to stemming used in this proposed
work is character n-gramtokenization. Adamson and Borehamin 1974 introduced n-gram
stemmersmethod[22] a conflating terms also called shared digram method. A digram is a pair of
consecutive letters. In this approach, n-gram method is used as association measures to calculate
distance between pairs of terms based on shared unique digrams. Formerly the distinctive digrams
for the word pair are articulated and counted, with a similarity quantifier called Dice’s coefficient
⁄
for computation. Dice’s coefficient is termed as
where
is the number of
distinctivedigrams in the first word, the number of distinctivedigrams in the second, and the
84


number of distinctivedigrams shared by and . This similarity quantifieris used to bentall pairs
of terms in the database, and also used to figure a similarity matrix.Since Dice coefficient is
symmetric, a lower triangle similarity matrix is used.At the end of first niche the text
preprocessing is well-rounded by building a strong bottomline and preparedness for accurate text
classification.

3.2.Second Niche – High-filers Identification, Elimination & k-MedoidsClustering
High-fliers are the noisy and redundant data present in a data set, they materialize to be
conflicting with the other residues in the data set. Such high-fliers are to be eliminated because
they are the applicant for abnormal data that unfavorably guide to sculpt vagueness, unfair
constraint inference and inaccurate domino effect. In text classification, High-fliers raise between
each category because of the uneven distribution of data, as which carries to that the distance
between samples in the same category to be larger than distance between samples in different
categories. This is addressed by building a Solemnity model in k-Medoids clustering algorithm.
3.2.1.Solemnity Model
To reduce the complexity of constricted training set, and overcome the uneven distribution of text
samples the k-Medoids clustering algorithm is used. The similarity measure used in identifying
the categories in training set was Levenshtein distance (LD) or Edit distance [23]. This
quantification is used a string metric for assessing the dissimilarityamidby the two successions.
(| | | |)where
Edit distance between two strings
is given by
(
(

)

)

)
)
)

(
(

{
{

(

(

)

otherwise, LD has numerous upper and
[

]

lower bounds. If the comparing strings are identical, it results zero. If the strings are of the
identical size, the Hamming distance is an upper bound on the LD distance. The LD between
twostrings is no greater than the sum of their LD from a third string. At the end of the second
niche, the high-fliers are eliminated and a solemnity model is built using k-Mddwith LD
similarity measure and the training set is rebuilt by partitioning the objects into different
categories, thus reduces the computational complexityand impacts on the memory usage tenancy.
The cluster centers are treated as the k representative’s objects in the constricted training set.

3.3.Final Niche – Appliance of AkNNand amending weights towards computed
centroid
The second niche classifies the objects in the training phase by building aconstricted training set
using k centroidsbut when an object from a testing set have to be classified, it is necessary to
calculate similarities between object in testing set and existing samples in it constricted training
sets. It then chooses k nearest neighbor samples, which have larger similarities, and amends
weights using weighting vector.
To accomplish this model Cosine similarity is used as a distance measure in kNNtext classifier to
classify the test sample towards the similarity with k samples in the training set. Cosine similarity
distance measure is commonly used in high dimensional positive spaces, used to compare
documents in text mining. IR uses this cosine similarity for comparing documents and to range
values from 0 to 1, since TF-IDF weights cannot be negative.Each term is speculatively dispensed
over a distinctive dimension and a vector is described for each document, where value of each
85


dimension matches to the number of times the term appeared in the document.The cosines of two
‖ ‖‖ ‖
vectors are resultant by using the Euclidean dot product formula
. Assumed
two vectors of attributes, A and B the cosine similarity, is symbolized using a dot product and
∑

magnitude as

‖ ‖‖ ‖

√∑

(

)

√∑

(

)

The ensuing similarity vary

from -1 (exactly opposite) to 1 (exactly the same), and with 0 (indicating independence). For text
similarities, the attribute vectors A and B are usually the TF vectors of the documents
3.3.1. Assigning weights to samples
To assign precedence to the samples in constricted training set that have high similarity with the
test sample the kNN classifier uses a distance weighted kNN rule proposed by Dudani[24].Let
be the weight of the
nearest samples. The WkNN rule resolves the weight
by using a
distance function between the test samples and the
nearest neighbor, i.e. samples with minor
distances are weighted more profoundly than with the larger distances. The simple function that
scales the weights linearly is

{

where

is the distance to the test

sample of the
nearest neighbor and the farthest ( ) neighbor respectively. The WkNN rule
uses the rank weighting function
to assign the weights. The proposed work used
this function for computing the weights of kNNsamples belonging to individual classes.
The upshot observed at the end of the final niche was the AkNN classifies the objects in testing
set with the distance weighted kNN rule compute ranks to each category and ranks k samples that
have high similarities and accessory towards the centroids. The Inactive amalgamation of
classification and clustering text categorization algorithm is obtainable as algorithm 1.
Algorithm1: Amalgamation of Classification and Clustering for Text Categorization
Input:A Raw training set composing of
predefined category lables
*
documents .

text documents
+ and c clusters

*

+, a set of
, and testing set sample

First niche
*
+, into vectors from
1: Preprocess the training set documents,
dataset
2: For each feature in the dataset do
3: Attribute feature selection by removing formatting, sentence segmentation, stop-word
removal, white space removal, weight calcuation, n-gram stemming
4: Compute DF, TF, IDF and TF-IDF
5: End for
Second niche
6:
7:
8:
9:

Recognize and purge high-fliers by building a solmenity model using Edit distance
Obtain constricted training set with the preprocessed text document collection
For each processed document in D do
Compute c clusters
, using K-Medoids clustering algorithm for all categories of
+documents
in *
10: For every cluster ID, generate and index the feature cluster vectors
86


11: Redistribute the constricted training set with cluster represetatives of each text categories.
12: End for
Final niche
13: For each processed document in D of constricted training set do
14: Classifythe testing set sample document using AkNN text classifer with Cosine
Simalirity over the constricted training set .
15: Assign the weights using distance weighted kNN rule to training set documents and
assign rank to k samples that has the largest similarity and belongingness to categories.
16: Position the testing set document to the categories C which has the largest similairy and
consign them with heavily weighted rank.
17: Build classifier on these mapped text document and record the classification accuray
18: End for
Output: Classifying testing documents

in to

categories with appropriate weight value

.

4. Experimental Analysis and Observations
4.1.Dataset
The referred algorithm uses Reuters-21578 a classical benchmark dataset for text categorization
classification [25]. Reuters 21578 consist documents from the Reuters newswire, which was
categorized and indexed in to grouping, by Reuters Ltd. and Carnegie Group in 1987. In 1991
David D. Lewis and Peter Shoemaker of Center for Informationand Language Studies, University
of Chicago prepared and formatted the metafile for the Reuters-21578 dataset [26]. The
experimental environment used is Intel core i3 CPU 530@2.93GHz 2.93 GHz, RAM 4GB, 32-bit
Windows OS, and Java software. The software Package html2text-1.3.2 is used to convert the text
corpus into text documents. The categories in text documents are separated as individual text
documents using Amberfish-1.6.4 software.Thetext corpus consists of 21,578 documents,
assigned with 123 different categories. Table 1 presents the initial distribution of all categories in
Reuters-21578 text corpos before it is preprocessed.
Table1. Initial distribution of all categories in Reuters 21578

Categories
Earn
Acq
Money
Fx
Crude
Grain
Trade
Interest
Wheat
Ship
Corn
Oil
Dlr
Gas
Oilseed
Supply

#Documents
3987
2448
991
801
634
628
552
513
306
305
255
238
217
195
192
190

Categories
Feed
Rubber
Zinc
Palm
Chem
Pet
Silver
Lead
Rapeseed
Sorghum
Tin
Metal
Strategic
Wpi
Orange
Fuel

#Documents
51
51
44
43
41
41
37
35
35
35
33
32
32
32
29
28

Categories
Potato
Propane
Austdlr
Belly
Cpu
Nzdlr
Plywood
Pork
Tapioca
Cake
Can
Copra
Dfl
F
Lin
Lit

#Documents
6
6
4
4
4
4
4
4
4
3
3
3
3
3
3
3
87


Sugar
Gnp
Coffee
Veg
Gold
Nat
Soybean
Bop
Livestock
Cpi
Reserves
Meal
Copper
Cocoa
Jobs
Carcass
Yen
Iron
Rice
Steel
Cotton
Ipi
Alum
Barley
Soy

184
163
145
137
135
130
120
116
114
112
84
82
78
76
76
75
69
67
67
67
66
65
63
54
52

Hog
Retail
Heat
Housing
Stg
Income
Lei
Lumber
Sunseed
Dmk
Tea
Oat
Coconut
Cattle
Groundnut
Platinum
Nickel
Sun
L
Rape
Jet
Debt
Instal
Inventories
Naphtha

27
27
25
21
21
18
17
17
17
15
15
14
13
12
12
12
11
10
9
9
8
7
7
7
7

Nkr
Palladium
Palmkernel
Rand
Saudriyal
Sfr
Castor
Cornglutenfeed
Fishmeal
Linseed
Rye
Wool
Bean
Bfr
Castorseed
Citruspulp
Cottonseed
Cruzado
Dkr
Hk
Peseta
Red
Ringgit
Rupiah
Skr

3
3
3
3
3
3
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1

In the first nitche preprocessing is imposed on the text corpos, further test the effectiveness and
efficiency of Category specific classification data set is divided according to the standard
Modified Apte split. This split results 13575 documents with training set, 6231documents with
testing set and removes 1771 documents from Reuters-21578 documents since they are not used
either in training or testing set. The utmost number of categories allocated to a document is 16
and its average value is 1.24.It also eliminates 47 categories that do not exist in both training and
testings set, thus a total number of distinct terms in the text corpos after preprocessing is 20298.
Table 2 list the top 12 categories with number of documents assigned both in training and testing
sets after completion of preprocessing.
Table 2. Top 12 categories in Reuters-21578 after preprocessing

4.2 Evaluation Measures
Information Retrieval (IR) is apprehensived with the directorialretrieval of information from a
outsized number of textdocuments.There are two basic criterions widely used in document
88


categorization field are precision and recall. Precision is the fraction of returned documents that
are correcttargets, while recall is the fraction of correct target documents returned.

,

Van Rijsbergen [28] introduced the F1 measure as an estimation to to evaluate the text
classification structure.It combines both recall and precision and is given as

(

)

,

where
score reaches its best value at 1 and worst score at 0. Accuracy is defined as the
percent of documents correctly classified in the classes based on the documents target labels.
The preprocessed text corpus was supplied as an input to the second nitche. The kMdd clustering
algorithm groups the documents in to differeent categories. Table 3 summarizes the results
after the application of k-Mdd clustering algorithm over the text corpus. Multiple category lables
that tends to high-fliers are discarded and for clustering accurary uplifment clusters having less
than 5 documents are also removed. The average number of categories per documentis 1.334 and
the average number of documentsper category is about 151 or 1.39% of thecorpus.Table 4 gives
the documents in cluster numbers 01 and cluster 06 and the set of categories associated with these
documents. Table 5 summarizes the total number of clusters generated holding minimum and
maximum number of text documents as cluster size. The k-Mdd clustering accuracy based on k
value is given in Table 6. An important observation from Table 6wasas the k value increases a
proportionate raise in computational time and plunge in accuracy is turned out.
Table 3. Results abridged after k-Medoids clustering on text corpus

Description
Total Number of documents
Number of documents used
Number of documents
Un-used
Number of clusters

Reuters
text corpus
21578
19806

Description
Max. cluster size
Min. cluster size

Reuters
text corpus
3854
5

1772

Average cluster size

171

123

Max. cluster size

3854

Table 4. Sample Cluster numbers with document identifiers and categories

Cluster
Number
01

06

Document ID’s
12385, 12874, 12459, 16518, 18719, 2059,
3150, 3565, 3864,4335, 5805, 5625, 6211, 6481,
6501, 6744, 7994, 8050, 8997, 8449, 8333, 9121,
9381, 9355, 9457
12664, 12378, 14712, 2539, 456, 2564, 3751,
5421, 6789, 64561, 6781, 6977, 7947, 8239

Categories
ship, earn, gas,
strategic, metal,
acq,grain ship, dlr,
trade, money,fx
earn, gas, strategic,
metal, acq, tin

At the end of second nitche the high-fliers are eliminated and training set text corpus is clustered
into different categories based on k-value. The ingrained final nitche is sequenced by triggering
89


the augumented kNN over training set and regaling solictations to testing set. The weighed vector
using distance weighted kNN rule is imposed over the testing set based on high similarites and
accessory towards the centroids for each categories in testing set.
It ranks the k nearest neighbors from the training set. The performance of AkNN text classifier
with and with out weighting vector using evaluation criterion and comparisions with traditonal
kNN is summarized as Table 7.
Table 5. Number of Clusters shaped with sizes

Size of clusters
(No.of
documents)
0-5
6-34
35-40
41-45
46-50
51-55
56-60

Total
No. of
Clusters
4
5
8
7
9
6

Size of clusters
(No.of
documents)
61-65
66-75
76-85
86-95
96-125
126-150
151-175

Total
No. of
Clusters
4
7
5
2
7
3
1

Size of clusters
(No.of
documents)
176-200
201-300
301-400
401-500
501-600
601-700
Total Clusters

Total
No. of
Clusters
3
7
1
1
2
2
84

Table 6. K-medoids clustering accuracy on text corpus based on k value.

k-Value
1
2
3
4
5
6

Accuracy(%)
0.9145
0.9622
0.7750
0.7586
0.6711
0.7162

CPU time (sec)
2.58
2.63
3.13
3.86
4.98
6.51

k-Value
7
8
9
10
15
20

Accuracy(%)
0.6230
0.5724
0.6185
0.6573
0.6091
0.5458

CPU time (sec)
08.43
09.73
24.28
30.65
56.53
57.26

Table 7. Preformance evaluation of AkNN text classifier on top 10 categories of Reuters-21578
Precesion

Recall

kNN

AkNN
without
Weights

AkNN
with
Weights

0.89
0.70
0.91
0.78
0.71
0.60
0.77
0.66
0.52
0.63

0.91
0.74
0.91
0.81
0.74
0.64
0.81
0.74
0.54
0.66

0.93
0.77
0.93
0.84
0.79
0.69
0.88
0.79
0.57
0.71

Categories

Acq
Crude
Earn
Grain
Interest
Money
Fx
Ship
Trade
Wheat

F-Measure

kNN

AkNN
without
Weights

AkNN
with
Weights

kNN

AkNN
without
Weights

AkNN
with
Weights

0.93
0.88
0.94
0.81
0.80
0.87
0.85
0.89
0.67
0.31

0.94
0.88
0.95
0.84
0.81
0.87
0.84
0.89
0.71
0.35

0.95
0.89
0.95
0.87
0.83
0.91
0.87
0.93
0.74
0.37

0.9096
0.7797
0.9248
0.7947
0.7523
0.7102
0.808
0.7579
0.5855
0.4155

0.9248
0.804
0.9296
0.8247
0.7734
0.7375
0.8247
0.8081
0.6134
0.4574

0.9399
0.8257
0.9399
0.8547
0.8095
0.7849
0.875
0.8543
0.644
0.4865

The momentous observation on F-measure from Table 7 proliferates AkNN with Weight as the
best performer, despite frantic attempts made by the enterent methods. Figure 2 exhibits the FMeasure dominance of weighted AkNN of Text classifiers over top 10 categories in Reuters text

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corpus. The text classifiers overall accuracy and CPU computational efficiency of AkNN with
and without weighting vector is compared with the traditional kNN and is shown as Table 8.
The significant surveillance from Table 8 was AkNN with Weight outperforms its competitor
both in training and testing phases. The overall accuray of conventional classifier could not tug at
the heartstring of white-collar expatriate of weighted vector AkNNs, thus it complains the proactiveness of amalgmative technique for text mining.

Figure 2. F-Measure of Text classifiers over top 10 categories in Reuters-21578 text corpus
Table 8. Comparision of Algorithms CPU Computational Time and accuracy

Modified Apte split
Training Set

AkNN with Weight
21.6 min

AkNN without Weight
58.47 min

kNN
1.50 hrs

Testing Set
Text Classifiers
overall Accuracy(%)

15.4 secs

51.42 sec

1.54 sec

0.942

0.951

0.873

5. Conclusion
Due to the exponential increase in huge volumes of text documents, there is a need for
analyzingtextcollections, so several techniques have been developed for mining knowledge from
textdocuments. To strengthen the expressiveness of text classification, a novel amalgamative
method using AkNN text classifier and kMdd clustering is tailored. It was well suited for
dimension reduction, attribute feature selection, high-flier identification and reduction, and
assigning weights/ ranks to k nearest neighbors using weighing vector. The experimental analysis
conducted on the benchmark dataset Reuters-21578 rationalizes the reference method
substantially and significantly surpasses traditional text categorization techniques, thus makes the
amalgamation method a very promising and easy-to-use method fortext categorization.
Further research may address the issue of reduction of computational cost, by using soft
computing approaches for text classification and clustering method. There is a scope to
investigate the adjustments in the weighting vector based on k- value in accordance to the size of
the categories and their belongingness to text classifier, thus speculating fruitful success in
deriving accuracy and high performance over training and testing set.

91


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Authors
RamachandraRaoKurada is currently working as Asst. Prof. in Department of Computer Applications at
Shri Vishnu Engineering College for Women, Bhimavaram. He has 12 years of teaching experience and is
a part-time Research Scholar in Dept. of CSE, ANU, Guntur under the guidance of Dr. K KarteekaPavan.
He is a lifemember of CSI and ISTE. His research interests are Computational Intelligence, Data warehouse
& Mining, Networking and Securities.
Dr. K. KarteekaPavan has received her PhD in Computer Science &Engg. fromAcharyaNagarjuna
University in 2011. Earlier she had received her postgraduate degree in Computer Applications from
Andhra University in 1996. She is having 16 years of teaching experience and currently working as
Professor in Department of Information Technology of RVR &JC College of Engineering, Guntur. She has
published more than 20 research publications in various International Journals and Conferences. Her
research interest includes Soft Computing, Bioinformatics, Data mining, and Pattern Recognition.

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Novel text categorization by amalgamation of augmented k nearest neighbourhoodclassification and k-medoids clustering

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