rime-pof-input-method

Pairs-of-five-strokes: An input method for writing Chinese characters on computers, primarily developed for the RIME input method editor. Created by Lykke (@Weiqifan1).

About the POF input method

Sound based input methods for chinese have been getting better and better with predictive text enhancements, but shape based input methods still have one big advantage over the sound based ones: they help preventing character amnesia (提筆忘字). The main problem with shape based input methods is that they are hard to learn. This is because in order to be practical, any shape based system has to allow the user to write any character with about the same number of keystrokes as sound based systems. This means that in order to prevent ambiguity (the same keystrokes can write a large number of different characters) the shape based systems use very complicated rules that make them hard to lean.

The motivation for creating the POF system was thus to create a system that was easy to lean, could write any (common use) character without the need for scrolling through a list, yet using no more than 4 keystrokes pr. character plus the 1-9 numberkeys for selection.

Here "common use" means that when using the POFsimp dict and schema files, you can write any of the first 5000 characters in this frequency list without scrolling:

https://lingua.mtsu.edu/chinese-computing/statistics/char/list.php?Which=IM

When using the POFtrad dict and schema files, you can write any of the first 5000 characters in this frequency list without scrolling:

http://technology.chtsai.org/charfreq/sorted.html

This system contains a total of 28098 different characters taken from this repository: https://github.com/stroke-input/stroke-input-data compiled by Conway (@yawnoc). Licensed under Creative Commons Attribution 4.0 International (CC-BY-4.0).

The IDS data used for creating the special functions for the 13 keys is the ids.tx file from this project: https://github.com/cjkvi/cjkvi-ids/blob/master/ids.txt Originally from https://www.chise.org/

How to use the POF system

To make it easy to learn, POF is fundamentally based on strokeorder. It uses the standard 5 strokes in this order:

horizontal: 一（heng 横， ti 提）

vertical：丨（shu 竖, shugou 竖钩）

left：丿（wan 弯, pie 撇）

right：丶（dian 点, na 捺）

bent：乚（all the bent strokes）

Each key correspond to two strokes according to this table:

For example, by pressing “g” you can write characters like 乙（a single bent stroke）or 刁（a bent stroke plus a horizontal stroke） by pressing “m” you can write for example 七 or 匕

Code examples

To write more complex characters, you combine keys like this:

戈 mw (m 一乚 + w 丿丶 )

If the number of strokes is uneven, for the last stroke you use one of the keys where the second stroke is 一, that is you use either T, Y, G, H or N:

戋 hdy （h 一一 + d 乚丿 + y 丶）

If the number of strokes is greater than 8, so you cant write the whole character with 4 keystrokes, you type the keys for the first 6 strokes, and the last two:

過 xnxs （x 亅乚 + n 亅一 + x 亅乚 + s 乚丶）

Some characters have a very complex set of strokes in the beginnning of the character that occur again and again in many characters. This means that the last two strokes you would write with the last key are not enough to disambiguate. The solution that POF uses is to use some keys to write certain shapes that occur often. Those can be seen on 13 of the keys in the table above. Here are some examples:

䟿 sajw 橲 djjg 简 fcfh 蝝 jakw 睌 kdxq 挡 lcqh

餂 whbg 詔 edxh 駊 rdxy 緇 uafn 軪 iapt 鐑 oaog 䦘 pgmw

As you can see from the character 鐑 oaog you only use a single key for these shapes if the shape is at the start of the character. So 鑫 is written owht and not ooo.

when writing the characters for the elemments themselves, you can either use the keys:

食 w 言 e 馬 r 糸 u 車 i 金 o 門 p 足 s 木 d 竹 f 虫 j 目 k 手 l

but you can also write those 13 characters with just strokes

食 wphw 言 yhxh 馬 nhxo 糸 auw 車 jghn 金 whct 門 xhxh 足 xjky 木 jw 竹 tvj 虫 xjl 目 xhh 手 tj

This means that if you are only going to write simplified character, you will only have to learn the special functions for 6 keys on the middle row: sdf and jkl, since the elements on the other 7 keys are not used for simplified characters. You therefore only have to learn all 13 if you write traditional characters.

If you dont like to use this special functionaly for the 13 keys, it is also possible to write characters using up to 6 keystrokes instead of 4, where you ignore the special functions of the 13 keys. For excample 詔 edxh can instead be written 詔 hhxmrg or yhxmrg.

Chinese punctuation characters and parenthesis can be written using the ,. and z key.

Examples: