Machine Learning With Orange: Clustering

Showing posts with label Clustering. Show all posts

Wednesday, 14 May 2014

Counting words - Clustering–Find Related post–part2

Key point

Euclidean distance comes under the unsupervised learning.

Why Euclidean distance?

Euclidean distance measures the distance between the two points in xy plane. formula Euclidean distance formula and its explanation can be seen in the below link. the formula will match exactly with our dist_raw(v1, v2) function.

http://www.cut-the-knot.org/pythagoras/DistanceFormula.shtml

Monday, 12 May 2014

Regex pattern in token_pattern for CountVectorizer

Regex

The result of the book showed

#samples: 5, #features: 25

[u'about', u'actually', u'capabilities', u'contains', u'data', u'databases', u'images', u'imaging', u'interesting', u'is', u'it', u'learning', u'machine', u'most', u'much', u'not', u'permanently', u'post', u'provide', u'safe', u'storage', u'store', u'stuff', u'this', u'toy']

There is one missing word in the above result that is “a”, which is there in the 01.txt of the toy posts.

01.txt This is a toy post about machine learning. Actually, it contains
not much interesting stuff.

Why it is missed?

This is caused by the default token_pattern for CountVectorizer, which removes tokens of a single character:

Default token_pattern for CountVectorizer is (?u)\b\w\w+\b, which removed single character word ‘a’.

`How to get the single character word?`

by changing token_pattern for CountVectorizer to \\b\\w+\\b we can see the single character in the result.

Do we need the single character word?

Depend on the apllication, we may need to extract single character words.

Ref

http://stackoverflow.com/questions/20717641/countvectorizer-i-not-showing-up-in-vectorized-text

Tuesday, 22 April 2014

Bag-Of-word using orange

for the main work of finding related post, we have to learn bag-of-words approach for text processing in machine learning.

in a default installation we do not have text processing widgets in orange, so we have to install addons. I installed Textable addon for this work.

1. From the Textable addon, add Text Field widget.

2. Copy & Paste the following text with in quotes

“How to format my hard disk

Hard disk format problems”

3. Add Textable\preprocessor to convert the text to smaller case. we are converting entire text smaller case. so that words of upper and lower case wont be separated as a different words. that is How and how wont be separated as a different word.

4. First we will segment the words in to lines. for this we will ad Textable\segment widget and configure it as shown in the below image.

Configuration of Textable\segment widget

Check advanced settings
Select mode to split
Set Regex .+, to specify lines.
Check Unicode dependent(u)
Click add
under options, Change the label name
Check the Auto-number with key and name it

5. We will segment it further to words. for this we will ad Textable\segment widget and configure it as shown in the below image.

Configuration of Textable\segment widget

Check advanced settings
Select mode to Tokenise
Set Regex \w+, to specify words.
Click add button
under options, change the segment label.

6. Count the segments based on the context and words. for this we will add Textable\count widget

set segmentation to words

mode to containing segmentation
segmentation to Lines
annotation key to num

7. Insert Texatable\Convert widget and connect to data/ table widget.

See the complete canvas

Special Thanks

Special thanks to Mr.Axanthos, Site Admin, Langtech.ch. I am new to Machine learning. I don’t know how to implement bag-of-word approach in orange and concept. I have made a support request in Langtech.ch/forums. for my request Mr. axanthos provided a clear explanation and code.

http://langtech.ch/forum/textable/viewtopic.php?f=4&t=12

Reference

http://langtech.ch/forum/textable/viewtopic.php?f=4&t=4

http://moodle2.unil.ch/course/view.php?id=574

https://orange-textable.readthedocs.org/en/latest/

http://orange.biolab.si/forum/viewtopic.php?f=4&t=1949#p5655

Friday, 18 April 2014

Counting words - Clustering–Find Related post–part1

assume in our website we already have few posts. we are going to find a most relevant post for the current viewing post “Imaging database”

the Below table shows existing posts in the websites

Si.No	Post Content
1	This is a toy post about machine learning. Actually, it contains not much interesting stuff.
2	Imaging databases can get huge.
3	Most imaging databases safe images permanently.
4	Imaging databases store images.
5	Imaging databases store images. Imaging databases store images. Imaging databases store images.

In the book, posts are opened using following script

Script1 – reading file and printing output

   1: import os

   2: import sys

   3: import scipy as sp

   4: from sklearn.feature_extraction.text import CountVectorizer

   5: data_Dir = "E:\\Machine Learning\\Orange\\Finding Related Post\\toy\\"

   6: posts = [open(os.path.join(data_Dir,f)).read() for f in os.listdir(data_Dir)]

   7: print posts

Result1:

"Running script:

['This is a toy post about machine learning. Actually, it contains not much interesting stuff.', 'Imaging databases provide storage capabilities.', 'Most imaging databases safe images permanently.', 'Imaging databases store data.', 'Imaging databases store data. Imaging databases store data. Imaging databases store data.']