Find characters that are similar glyphically in Unicode?

Question

Lets say I have the characters Ú, Ù, Ü. All of them are similar glyphically to the English U.

Is there some list or algorithm to do this:

• Given a Ú or Ù or Ü return the English U
• Given a English U, return the list of all U-similar characters

I'm not sure if the code point of the Unicode characters is the same across all fonts? If it is, I suppose there could be some easy way and efficient to do this?

UPDATE

If you're using Ruby, there is a gem available unicode-confusable for this that may help in some cases.

Answer 1

It is very unclear what you are asking to do here.

• There are characters whose canonical decompositions all start with the same base character: e, é, ê, ë, ē, ĕ, ė, ę, ě, ȅ, ȇ, ȩ, ḕ, ḗ, ḙ, ḛ, ḝ, ẹ, ẻ, ẽ, ế, ề, ể, ễ, ệ, e̳, … or s, ś, ŝ, ş, š, ș, ṡ, ṣ, ṥ, ṧ, ṩ, ….

• There are characters whose compatibility decompositions all include a particular character: ᵉ, ₑ, ℯ, ⅇ, ⒠, ⓔ, ㋍, ㋎, ｅ, … or s, ſ, ˢ, ẛ, ₨, ℁, ⒮, ⓢ, ㎧, ㎨, ㎮, ㎯, ㎰, ㎱, ㎲, ㎳, ㏛, ſt, st, ｓ, … or R, ᴿ, ₨, ℛ, ℜ, ℝ, Ⓡ, ㏚, Ｒ, ….

• There are characters that just happen to look alike in some fonts: ß and β and ϐ, or 3 and Ʒ and Ȝ and ȝ and ʒ and ӡ and ᴣ, or ɣ and ɤ and γ, or F and Ϝ and ϝ, or B and Β and В, or ∅ and ○ and 0 and O and ০ and ੦ and ౦ and ૦, or 1 and l and I and Ⅰ and ᛁ and | and ǀ and ∣, ….

• Characters that are the same case-insensitively, like s and S and ſ, or ss and Ss and SS and ß and ẞ, ….

• Characters that all have the same numeric value, like all these for the value 1: 1¹١۱߁१১੧૧୧௧౧౹౼೧൧๑໑༡၁႑፩១៱᠑᥇᧑᧚᪁᪑᭑᮱᱁᱑₁⅟ ① ⑴ ⒈ ⓵ ❶➀➊꘡꣑꤁꧑꩑꯱𐄇𐅂𐅘𐅙𐅚𐌠𐏑𐒡𐡘𐤖𐩀𐩽𐭘𐭸𐹠𒐕𒐞𒐬𒐴𒑏𒑘𝍠𝟏𝟙𝟣𝟭𝟷 🄂 Ⅰⅰꛦ㆒㈠㊀𑁒𑁧.

• Characters that all have the same primary collation strength, like all these that are the same as d: DdÐðĎďĐđ◌ͩᴰᵈᶞ◌ᷘ◌ᷙḊḋḌḍḎḏḐḑḒḓⅅⅆⅮⅾ Ⓓ ⓓ ꝹꝺＤｄ𝐃𝐝𝐷𝑑𝑫𝒅𝒟𝒹𝓓𝓭𝔇𝔡𝔻𝕕𝕯𝖉𝖣𝖽𝗗𝗱𝘋𝘥𝘿𝙙𝙳𝚍 🄳 🅓 🅳 🇩 . Note that some of those are not accessible through any kind of decomposition, but only through the DUCET/UCA values; for example, the fairly common ð or the newish ꝺ can be equated to d only through a primary UCA strength comparison; same with ƶ and z, ȼ and c, etc.

• Characters that are same in certain locales, like æ and ae, or ä and ae, or ä and aa, or MacKinley and McKinley, …. Note that locale can make a really big difference, since in some locales both c and ç are the same character while in others they are not; similarly for n and ñ, or a and á and ã, ….

Some of these can be handled. Some cannot. All require different approaches depending on different needs.

What is your real goal?