execute python in a new window

vim/ftplugin/python.vim

@@ -4,3 +4,6 @@ set shiftwidth=4
 set expandtab
 set shiftround
 set autoindent
+
+nnoremap <silent> <buffer> <F5> :call SaveAndExecutePython()<CR> 
+" vnoremap <silent> <buffer> <F5> :<C-u>call SaveAndExecutePython()<CR> 

vimrc.functions.vim

@@ -138,6 +138,60 @@ function! s:RunShellCommand(cmdline) abort
 endfunction
 "}}}
 
+" https://stackoverflow.com/a/40195855
+function! SaveAndExecutePython()
+    " SOURCE [reusable window]: https://github.com/fatih/vim-go/blob/master/autoload/go/ui.vim
 
+    " save and reload current file
+    silent execute "update | edit"
+
+    " get file path of current file
+    let s:current_buffer_file_path = expand("%")
+
+    let s:output_buffer_name = "Python"
+    let s:output_buffer_filetype = "output"
+
+    " reuse existing buffer window if it exists otherwise create a new one
+    if !exists("s:buf_nr") || !bufexists(s:buf_nr)
+        silent execute 'top new ' . s:output_buffer_name
+        let s:buf_nr = bufnr('%')
+    elseif bufwinnr(s:buf_nr) == -1
+        silent execute 'top new'
+        silent execute s:buf_nr . 'buffer'
+    elseif bufwinnr(s:buf_nr) != bufwinnr('%')
+        silent execute bufwinnr(s:buf_nr) . 'wincmd w'
+    endif
+
+    silent execute "setlocal filetype=" . s:output_buffer_filetype
+    setlocal bufhidden=delete
+    setlocal buftype=nofile
+    setlocal noswapfile
+    setlocal nobuflisted
+    setlocal winfixheight
+    setlocal cursorline " make it easy to distinguish
+    setlocal nonumber
+    setlocal norelativenumber
+    setlocal showbreak=""
+
+    nnoremap <buffer> q :bdelete<CR> 
+
+    " clear the buffer
+    setlocal noreadonly
+    " setlocal modifiable
+    %delete _
+
+    " add the console output
+    silent execute ".!python " . shellescape(s:current_buffer_file_path, 1)
+
+    " resize window to content length
+    " Note: This is annoying because if you print a lot of lines then your code buffer is forced to a height of one line every time you run this function.
+    "       However without this line the buffer starts off as a default size and if you resize the buffer then it keeps that custom size after repeated runs of this function.
+    "       But if you close the output buffer then it returns to using the default size when its recreated
+    "execute 'resize' . line('$')
+
+    " make the buffer non modifiable
+    setlocal readonly
+    " setlocal nomodifiable
+endfunction
 
 " vim: foldmethod=marker