How to Specify the Gap Between Index Entries

Question

The code

\documentclass{book}
\usepackage{imakeidx}
\let\cleardoublepage\clearpage
\makeindex
\usepackage[itemlayout=singlepar]{idxlayout}

\begin{document}
\LARGE

This is the first paragraph.\index{AA! first}\index{AA! second}\index{AA! third}

This is the second paragraph.\index{AAB! an entry}

This is the third paragraph.\index{AAC! another entry}

\idxlayout{columns=1}
\printindex
\end{document}

produces the index:

How may I specify ahead of time the gap (say, 5pt, 10pt, 12pt, etc.) between AA and AAB; between AAB and AAC ?

Answer 1

Redefine \@idxitem to add some vertical space.

\documentclass{book}
\usepackage{imakeidx}
\usepackage[itemlayout=singlepar]{idxlayout}

\makeindex

\makeatletter
\renewcommand{\@idxitem}{\par\addvspace{\medskipamount}\hangindent40\p@}
\makeatother

\begin{document}

This is the first paragraph.\index{AA! first}\index{AA! second}\index{AA! third}

This is the second paragraph.\index{AAB! an entry}

This is the third paragraph.\index{AAC! another entry}

\idxlayout{columns=1}

\printindex

\end{document}