[Tex/LaTex] using more than 2 arguments in a pgfplots style

macrospgfplots

Based on How to plot data from multiple filters using pgfplots I got a follow up one. I would like to filter not only for one value of P for each plot but for also for X values that are smaller than a given value. Here is how I tried to achieve it. 

  \pgfplotsset{
    discard if not and smaller/.style 4 args={
        x filter/.code={
            \edef\tempa{\thisrow{#1}}
            \edef\tempb{#2}
            \edef\tempc{\thisrow{#3}}
            \edef\tempd{#4}
            \ifnum\tempa=\tempb
                \ifnum\tempc<\tempd
                    \def\pgfmathresult{inf}
                \else
                \fi
            \else
                \def\pgfmathresult{inf}
            \fi
        }
    }
    }

    \begin{tikzpicture}
    \begin{axis}
    \addplot [ultra thick, black, discard if not and smaller={P}{0}{X}{5}] table [x=X, y=Y] {data.dat};
    \end{tikzpicture}

But pdfLaTeX tells me that:

! Package pgfkeys Error: I do not know the key '/pgfplots/discard if not and sm
aller/.style 4 args' and I am going to ignore it. Perhaps you misspelled it.

How can I pass these 4 arguments so that pgfplots find the style definition?

Best Answer

More than two arguments require /.style n args={no of args}{....} or /.code n args={no of arguments}{....}

  \pgfplotsset{
    discard if not and smaller/.style n args={4}{
        x filter/.code={
            \edef\tempa{\thisrow{#1}}
            \edef\tempb{#2}
            \edef\tempc{\thisrow{#3}}
            \edef\tempd{#4}
            \ifnum\tempa=\tempb
                \ifnum\tempc<\tempd
                    \def\pgfmathresult{inf}
                \else
                \fi
            \else
                \def\pgfmathresult{inf}
            \fi
        }
    }
    }

    \begin{tikzpicture}
    \begin{axis}
    \addplot [ultra thick, 
              black, 
              discard if not and smaller={P}{0}{X}{5}] table [x=X, y=Y] {data.dat};
    \end{tikzpicture}

If you have a certain pattern when entering these arguments instead of consecutive braces {1}{2}{3}{4} etc. you can also use 

/.style args={#1 and #2 using color #3 and size #4}

or anything else so that you can supply arguments 

mykey=a and b using color white and size 2cm

Same holds for /.code args too.

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