hhline drawn over vertical lines in a table

Question

Hi I am quite new to LaTeX and have attempted to put a table together as follows:

It is pretty close to what I want but I can't seem to find a way to separate the last three columns with white space. I've used hhline to draw the purple line so that it fills in the horizontal gap but I do not want it to show up in white spaces between each column. This is what I want as the end result

Any help would be greatly appreciated and am happy for any suggestions on how to approach this.

Cheers.

JT

\documentclass[a4paper]{article}
\usepackage{colortbl,multirow,hhline, xcolor}
\usepackage[margin=2cm]{geometry}

\begin{document}

% Define colours and columns
\definecolor{Purple}{RGB}{101, 60, 139}
\newcolumntype{?}{!{\color{white}\vrule width 1.5mm}}
\newcolumntype{P}[1]{>{\raggedright\let\newline\\\arraybackslash\hspace{0pt}}p{#1}}
\arrayrulecolor{white}


% Document
\begin{tabular}{P{5cm}c|c|cccc}
    \hline
    % R1C1
    \cellcolor{Purple} & 
    % R1C2-4
    \multicolumn{3}{?c?}{\cellcolor{Purple}\textcolor{white}{Combined cell heading}} &  
    % R1C5
    \multicolumn{1}{c?}{\cellcolor{Purple}} & 
    % R1C6 
    \multicolumn{1}{c?}{\cellcolor{Purple}} & 
    % R1C7
    \multicolumn{1}{c}{\cellcolor{Purple}}\\
    % Drawing line to split first row
    \hhline{>{\arrayrulecolor{Purple}}->{\arrayrulecolor{white}}--->{\arrayrulecolor{Purple}}--->{\arrayrulecolor{white}}}
    % R2C1
    \multirow{1}{*}{\cellcolor{Purple}\textcolor{white}{A}} & 
    % R2C2
    \multicolumn{1}{?c!{\color{white}\vrule width 1pt}}{\cellcolor{Purple}\textcolor{white}{B}}  & 
    % R2C3
    \multicolumn{1}{|c!{\color{white}\vrule width 1pt}}{\cellcolor{Purple}\textcolor{white}{C}}  & 
    % R2C4
    \multicolumn{1}{|c?}{\cellcolor{Purple}\textcolor{white}{D}}  & 
    % R2C5
    \multicolumn{1}{P{1cm}?}{\cellcolor{Purple}\textcolor{white}{E}} & 
    % R2C6
    \multicolumn{1}{P{1cm}?}{\cellcolor{Purple}\textcolor{white}{F}} &
    % R2C7
    \multicolumn{1}{P{1cm}}{\cellcolor{Purple}\textcolor{white}{G}}\\
\end{tabular}
\end{document}

Answer 1

This was a very challenging one. I have simplified your code, removed seemingly unnecessary \multirow and \multicolumn. The reason for you problem was the ?-column, because hhline did not recognise it as a column, so it was not possible to ‘cross’ it the correct way.

Here is the result and the code:

\documentclass[a4paper]{article}
\usepackage{multirow,hhline}
\usepackage[table]{xcolor}
\usepackage[margin=2cm]{geometry}

\renewcommand{\arraystretch}{1.2}
\setlength{\extrarowheight}{1pt}

\begin{document}

% Define colours and columns
\definecolor{Purple}{RGB}{101, 60, 139}

\newcolumntype{L}[1]{>{\raggedright\let\newline\\\arraybackslash\hspace{0pt}}p{#1}}
\newcolumntype{C}[1]{>{\centering\let\newline\\\arraybackslash\hspace{0pt}}p{#1}}

\arrayrulecolor{white}
\setlength\arrayrulewidth{0.5mm}


\begin{tabular}{L{5cm}||c|c|c||C{1cm}||C{1cm}||C{1cm}}
    \hline
    % R1C1
    \cellcolor{Purple} & 
    % R1C2-4
    \multicolumn{3}{c||}{\cellcolor{Purple}\textcolor{white}{Combined cell heading}} &  
    % R1C5
    \cellcolor{Purple} & 
    % R1C6 
    \cellcolor{Purple} & 
    % R1C7
    \cellcolor{Purple}\\
    % Drawing line to split first row
    \hhline{>{\arrayrulecolor{Purple}}->{\arrayrulecolor{white}}||---||>{\arrayrulecolor{Purple}}->{\arrayrulecolor{white}}||>{\arrayrulecolor{Purple}}->{\arrayrulecolor{white}}||>{\arrayrulecolor{Purple}}-}
    % R2C1
    \cellcolor{Purple}\textcolor{white}{A} & 
    % R2C2
    \cellcolor{Purple}\textcolor{white}{B} & 
    % R2C3
    \cellcolor{Purple}\textcolor{white}{C} & 
    % R2C4
    \cellcolor{Purple}\textcolor{white}{D} & 
    % R2C5
    \cellcolor{Purple}\textcolor{white}{E} & 
    % R2C6
    \cellcolor{Purple}\textcolor{white}{F} &
    % R2C7
    \cellcolor{Purple}\textcolor{white}{G}\\
\end{tabular}


\end{document}

Answer 2

With {NiceTabular} of nicematrix (with the latest version : 5.2 2020-08-19), you have directly the expected result (because \cline is respected by the coloring tools provided by {NiceTabular}).

\documentclass{article}

\usepackage{nicematrix}
\usepackage{xcolor}

\begin{document}

\arrayrulecolor{white}
\doublerulesepcolor{white}

\begin{NiceTabular}{wl{5cm}||wc{1cm}|wc{1cm}|wc{1cm}||wl{1cm}||wl{1cm}||wl{1cm}}%
 [ code-before = \rowcolor[RGB]{101, 60, 139}{1,2} ]
& \Block{1-3}{\color{white}Combined cell heading} \\
\cline{2-4}
\color{white}A &\color{white} B &\color{white} C &\color{white} D &\color{white} E &\color{white} F &\color{white} G 
\end{NiceTabular}

\end{document}