How Tamil Unicode works

Tamil has 247 characters. No panic. It is simple. 12 uyir eluthu(அ,ஆ..ஔ), 18 mei eluthu(க்,ங்..) , 216 uyirmei eluthu(12 * 18 க,ங ).1 ayutham(ஃ).

I assume you know what is unicode. If not read The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets and then read wikipedia page. You will understand most of it. Back to the post.

Every character or letter in unicode has value called code point. This is similar to ASCII where value of a is 97. All code point value is represented in hexadecimal. Tamil unicode character range starts from 0B80 - 0BFF. Unicode consortium has a complete mappings. So value of அ is 0B85.

You don’t believe me ? I will show you the code. Fireup python2 console(I am using ipython).

In [343]: print(unichr(0x0b85))
அ

How to find hex of a character ?

In [344]: print(hex(ord(u'க')))
0xb95

What is the code point of கி?

In [345]: print(hex(ord(u'கி')))
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-345-9e02bf5958df> in <module>()
----> 1 print(hex(ord(u'கி')))

TypeError: ord() expected a character, but string of length 2 found

Python says len of the unicode character கி is 2. Lets check.

In [346]: print(len(u'கி'))
2

In [348]: print(len(unichr(0x0b85)))
1

In [349]: print(unichr(0x0b85))
அ

So clearly கி is composed of two characters.கி=க்+ from language point of view. Lets see what program says.

In [355]: for c in u'கி':
    print c, hex(ord(c))
   .....:
க 0xb95
 ி 0xbbf

When you are typing in browser or editor, you use + after that it is the work of font and others work to replace it.

Below is the javascript code executed in chrome console.

chr = "கி"
for (var i in chr){console.log(chr[i]);}
க
ி
undefined

So irrespective of the programming language or console or browser unicode is stored in the same way.

ிis dependent vowel sign. Let me list all of them.

In [362]: for c in range(0xbbe, 0xbce):
    print c, unichr(c)
   .....:
3006 ா
3007 ி
3008 ீ
3009 ு
3010 ூ
3011 ௃
3012 ௄
3013 ௅
3014 ெ
3015 ே
3016 ை
3017 ௉
3018 ொ
3019 ோ
3020 ௌ
3021 ்

is a placeholder and that hex value doesn’t have any symbol or character. Dependent vowel will be used for replacing uyir eluthu.

Now lets read character by character in a word .

In [366]: for i in u'விகடகவி':
        print i, hex(ord(i))
   .....:
வ 0xbb5
 ி 0xbbf
க 0xb95
ட 0xb9f
க 0xb95
வ 0xbb5
 ி 0xbbf

Well above logic holds true for english but not for Tamil.

In [395]: word = u'விகடகவி'

In [396]: dependent_vowel_range = range(0xbbe, 0xbce)

In [397]: pos, stop = 0, len(word) - 1

In [398]: while not pos >= stop:
    #check if next char is dependent vowel if so, print together
    if ord(word[pos+1]) in dependent_vowel_range:
        print word[pos], word[pos+1]
        pos += 2
    else:
        print word[pos]
        pos += 1
வ ி
க
ட
க
வ ி

Now try to write a program that will find a tamil word is palindrome or not and see the fun.

Note: I need to figure font that will club dependent vowel and print properly in terminal.

See also

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