How do I remove Chinese characters from string B whenever they occur in string A, while preserving the order?

Question

I have some long strings of Chinese characters, but for the sake of the question, let's suppose they are:

啊爱好情人心安静排全装按照八把握爸吧白菜酒色夭百班长板

and

阿姨啊挨打矮小爱国护安检慰置岸边上按摩时案子暗示巴士拔

The first string lists all of the "easy" Chinese characters. The second string lists all "easy" and "intermediate" Chinese characters, but I only want the "intermediate" Chinese characters: I want to delete the "easy" characters from the second string.

E.g. after editing, the second string will not contain 啊 nor 爱 (and perhaps more deletions) since they both occur in the first string.

Question: How do I remove Chinese characters from string B whenever they occur in string A, while preserving the order?

I feel like this should be solvable with awk or sed or something; I don't mind. It looks like I could convert these strings to two text files, and use any one of the commands in How to remove the lines which appear on file B from another file A? However, I'd rather do it without creating auxiliary files.

It's also important to retain the order of the characters in the strings.

Answer 1

In shells that allow the syntax ${parameter/pattern/string} (ksh,bash,zsh) you can do:

$ easy='啊爱好情人心安静排全装按照八把握爸吧白菜酒色夭百班长板'
$ intermediate='阿姨啊挨打矮小爱国护安检慰置岸边上按摩时案子暗示巴士拔'

$ echo "${intermediate//[$easy]/}" 
阿姨挨打矮小国护检慰置岸边上摩时案子暗示巴士拔

That is based on a regex-like selection of characters […].
All individual characters in intermediate that also exist in easy will be erased.

An equivalent that is independent of the shell may be:

$ echo "$intermediate" | sed 's/['"$easy"']//g'

阿姨挨打矮小国护检慰置岸边上摩时案子暗示巴士拔

Answer 2

using Raku (née Perl6)

Raku was designed from the ground-up to handle Unicode gracefully. First example of each pair below generally from the Raku docs; second example of each pair adapted to solve with your particular Chinese strings:

$ echo "a123b123c" | raku -pe 'tr:d/123//;'
abc
$ echo "阿姨啊挨打矮小爱国护安检慰置岸边上按摩时案子暗示巴士拔" | raku -pe 'tr:d/啊爱好情人心安静排全装按照八把握爸吧白菜酒色夭百班长板//;'
阿姨挨打矮小国护检慰置岸边上摩时案子暗示巴士拔

OR

$ echo "a123b123c" | raku -pe '.=trans("123" => "");'
abc
$ echo "阿姨啊挨打矮小爱国护安检慰置岸边上按摩时案子暗示巴士拔" | raku -pe '.=trans("啊爱好情人心安静排全装按照八把握爸吧白菜酒色夭百班长板" => "");'
阿姨挨打矮小国护检慰置岸边上摩时案子暗示巴士拔

The -pe command-line flags instruct Raku to take input linewise and autoprint the return value(s). There are minor differences between the tr/// operator and the trans() routine. Docs below, HTH.

https://docs.raku.org/language/operators#tr///_in-place_transliteration
https://docs.raku.org/routine/trans
https://raku.org/

Answer 3

I figured it out! It may not be the best solution, but it works:

echo 阿姨啊挨打矮小爱国护安检慰置岸边上按摩时案子暗示巴士拔 | sed -e "s/.\{1\}/&\n/g" | awk -v pat="啊爱好情人心安静排全装按照八把握爸吧白菜酒色夭百班长板" 'pat ~ $0' | tr -d '\n'

Explanation:

• echo 阿姨啊挨打矮小爱国护安检慰置岸边上按摩时案子暗示巴士拔 is a way to pipe the second string as input
• sed -e "s/.\{1\}/&\n/g" adds a newline after each character
• awk -v pat="啊爱好情人心安静排全装按照八把握爸吧白菜酒色夭百班长板" 'pat !~ $0' prints only the characters that do not occur in pat (the first string)
• tr -d '\n' gets rid of all the newlines

It gives the output

阿姨挨打矮小国护检慰置岸边上摩时案子暗示巴士拔

and removes the characters 啊, 爱, 安, and 按.