Need to change section to Roman, but keep Arabic for for subsection and subsubsection

Question

I need to change my section numbering from Arabic, to Roman, beet keep the Arabic numbering in subsections and subsubsections. For example:

I. Section

1.1. Subsection

1.1.1. Subsubsection

II. Section

2.1 Subsection

...

So I know that with sections i can do "\renewcommand \thesection{\roman{section}}", but this command changes also subsections and subsubsections, like that:

I. Section

I.1. Subsection

I.1.1. Subsubsection

II Section

II.1. Subsection

...

So I need to keep subsections ans subsubsections from Roman numbering.

Answer 1

These two lines did it for me:

\renewcommand \thesection{\roman{section}}
\renewcommand \thesubsection{\arabic{section}.\arabic{subsection}}

Subsubsection also works, I assume because it takes its section number from subsection.