Convert ASCII chars to Unicode FULLWIDTH latin letters in Python?

The range of fullwidth ASCII replacements starts at U+FF01, not U+FF00. U+FF00 is (strangely) not defined. To get a fullwidth SPACE, you need to use U+3000 IDEOGRAPHIC SPACE. Don't rely on typing what appears to be what you want followed by visual inspection of characters to check your mapping -- unicodedata.name is your friend. This code:

# coding: utf-8
from unicodedata import name as ucname

# OP
normal = u"""0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&()*+,-./:;<=>?@[\\]^_`{|}~"""
wide = u"""０１２３４５６７８９ａｂｃｄｅｆｇｈｉｊｋｌｍｎｏｐｑｒｓｔｕｖｗｘｙｚＡＢＣＤＥＦＧＨＩＪＫＬＭＮＯＰＱＲＳＴＵＶＷＸＹＺ！゛＃＄％＆（）＊＋、ー。／：；〈＝〉？＠［\\］＾＿‘｛｜｝～"""
# above after editing (had = twice)
widemapOP = dict((ord(x[0]), x[1]) for x in zip(normal, wide))

# Ingacio V
normal = u' 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&()*+,-./:;<=>?@[\\]^_`{|}~'
wide = u'　０１２３４５６７８９ａｂｃｄｅｆｇｈｉｊｋｌｍｎｏｐｑｒｓｔｕｖｗｘｙｚＡＢＣＤＥＦＧＨＩＪＫＬＭＮＯＰＱＲＳＴＵＶＷＸＹＺ！゛＃＄％＆（）＊＋、ー。／：；〈＝〉？＠［\\］＾＿‘｛｜｝～'
widemapIV = dict((ord(x[0]), x[1]) for x in zip(normal, wide))

# JM
widemapJM = dict((i, i + 0xFF00 - 0x20) for i in xrange(0x21, 0x7F))
widemapJM[0x20] = 0x3000 # IDEOGRAPHIC SPACE

maps = {'OP': widemapOP, 'IV': widemapIV, 'JM': widemapJM}.items()

for i in xrange(0x20, 0x7F):
    a = unichr(i)
    na = ucname(a, '?')
    for tag, widemap in maps:
        w = a.translate(widemap)
        nw = ucname(w, '?')
        if nw != "FULLWIDTH " + na:
            print "%s: %04X %s => %04X %s" % (tag, i, na, ord(w), nw)

when run shows what you have really got: some missing mappings and some idiosyncratic mappings:

JM: 0020 SPACE => 3000 IDEOGRAPHIC SPACE
IV: 0020 SPACE => 3000 IDEOGRAPHIC SPACE
OP: 0020 SPACE => 0020 SPACE
IV: 0022 QUOTATION MARK => 309B KATAKANA-HIRAGANA VOICED SOUND MARK
OP: 0022 QUOTATION MARK => 309B KATAKANA-HIRAGANA VOICED SOUND MARK
IV: 0027 APOSTROPHE => 0027 APOSTROPHE
OP: 0027 APOSTROPHE => 0027 APOSTROPHE
IV: 002C COMMA => 3001 IDEOGRAPHIC COMMA
OP: 002C COMMA => 3001 IDEOGRAPHIC COMMA
IV: 002D HYPHEN-MINUS => 30FC KATAKANA-HIRAGANA PROLONGED SOUND MARK
OP: 002D HYPHEN-MINUS => 30FC KATAKANA-HIRAGANA PROLONGED SOUND MARK
IV: 002E FULL STOP => 3002 IDEOGRAPHIC FULL STOP
OP: 002E FULL STOP => 3002 IDEOGRAPHIC FULL STOP
IV: 003C LESS-THAN SIGN => 3008 LEFT ANGLE BRACKET
OP: 003C LESS-THAN SIGN => 3008 LEFT ANGLE BRACKET
IV: 003E GREATER-THAN SIGN => 3009 RIGHT ANGLE BRACKET
OP: 003E GREATER-THAN SIGN => 3009 RIGHT ANGLE BRACKET
IV: 005C REVERSE SOLIDUS => 005C REVERSE SOLIDUS
OP: 005C REVERSE SOLIDUS => 005C REVERSE SOLIDUS
IV: 0060 GRAVE ACCENT => 2018 LEFT SINGLE QUOTATION MARK
OP: 0060 GRAVE ACCENT => 2018 LEFT SINGLE QUOTATION MARK

Those "wide" characters are named FULLWIDTH LATIN LETTER: http://www.unicodemap.org/range/87/Halfwidth%20and%20Fullwidth%20Forms/

They have range 0xFF00 - -0xFFEF. You can make look-up table or just add 0xFEE0 to ASCII code.

Yes; in Python 3, cleanest is to use str.translate and str.maketrans:

HALFWIDTH_TO_FULLWIDTH = str.maketrans(
    '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&()*+,-./:;<=>?@[]^_`{|}~',
    '０１２３４５６７８９ａｂｃｄｅｆｇｈｉｊｋｌｍｎｏｐｑｒｓｔｕｖｗｘｙｚＡＢＣＤＥＦＧＨＩＪＫＬＭＮＯＰＱＲＳＴＵＶＷＸＹＺ！゛＃＄％＆（）＊＋、ー。／：；〈＝〉？＠［］＾＿‘｛｜｝～')

def halfwidth_to_fullwidth(s):
    return s.translate(HALFWIDTH_TO_FULLWIDTH)

In Python 2, str.maketrans is instead string.maketrans and doesn’t work with Unicode characters, so you need to make a dictionary, as Ignacio Vazquez notes above.

Yes.

>>> normal = u' 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&()*+,-./:;<=>?@[\\]^_`{|}~'
>>> wide = u'　０１２３４５６７８９ａｂｃｄｅｆｇｈｉｊｋｌｍｎｏｐｑｒｓｔｕｖｗｘｙｚＡＢＣＤＥＦＧＨＩＪＫＬＭＮＯＰＱＲＳＴＵＶＷＸＹＺ！゛＃＄％＆（）＊＋、ー。／：；〈＝〉？＠［\\］＾＿‘｛｜｝～'
>>> widemap = dict((ord(x[0]), x[1]) for x in zip(normal, wide))
>>> print u'Hello, world!'.translate(widemap)
Ｈｅｌｌｏ、　ｗｏｒｌｄ！