Python: How can I replace full-width characters with half-width characters?

Question

If this was PHP, I would probably do something like this:

function no_more_half_widths($string){
  $foo = array('１','２','３','４','５','６','７','８','９','１０')
  $bar = array('1','2','3','4','5','6','7','8','9','10')
  return str_replace($foo, $bar, $string)
}

I have tried the .translate function in python and it indicates that the arrays are not of the same size. I assume this is due to the fact that the individual characters are encoded in utf-8. Any suggestions?

Answer 1

The built-in unicodedata module can do it:

>>> import unicodedata
>>> foo = u'１２３４５６７８９０'
>>> unicodedata.normalize('NFKC', foo)
u'1234567890'

The “NFKC” stands for “Normalization Form KC [Compatibility Decomposition, followed by Canonical Composition]”, and replaces full-width characters by half-width ones, which are Unicode equivalent.

Note that it also normalizes all sorts of other things at the same time, like separate accent marks and Roman numeral symbols.