Vim mapping: Copy whole line X lines up/down and paste it X lines down/up

Question

I find myself doing the following very often: xkyyxjp (where x is a number).

I copy a whole line x lines up, and then I paste it x lines down (and vice versa); and so I wanted to make a map so I can do it automatically, ideally with: x<Leader>u, where x is the number and u is the letter that indicates the mapping. I tried:

nnoremap <Leader>u @='jyy'<CR>

and

nnoremap <expr> <Leader>u v:count1 kyy v:count1 jp

How could I write said mapping? Is there an already built-in key that does this?

Answer 1

You can use :copy or a shortcut :t command for that:

:10t20

it will copy line 10 below line 20.

Or copy 10 previous lines below line 20:

:-10,t20

Instead of copying text directly to the buffer you can use :yank or :y command instead to yank lines:

:-10,y

and then paste with p. This you can map as:

nnoremap <space>u <cmd>exe "-" .. (v:count1 - 1) .. ",y"<CR>

Where :exe executes a "string" you can construct with string concatenation ... And <cmd>expression<cr> is the way to execute a command without changing modes.

If you want to yank a single line located before cursor then :-10y should do it, and a mapping:

nnoremap <space>u <cmd>exe "-" .. v:count1 .. "y"<cr>