Often I like to define my own functions that are almost exactly the same as Mathematica defined functions, apart from a few tweaks. See this question for example. I want to define them properly so they handle optional arguments correctly. What is a general strategy for accomplishing this? Here's a concrete (esoteric) example. I define myListPlot that is almost identical to ListPlot except that is adds a gridline corresponding to the first data point.

data = Table[RandomReal[], {x, 1, 10}]
myListPlot[data_, opts_] := ListPlot[data, GridLines -> {None, {data[[1]]}}, opts]
myListPlot[data, {PlotStyle -> Red, Joined -> True}]

The ListPlot generated by the above code

Not too bad. However I have to pass the optional arguments as a list. Instead, I would like to pass the optional arguments in the same way one does with ListPlot. In other words, I would like to modify myListPlot so that I would pass arguments like

myListPlot[data, PlotStyle -> Red, Joined -> True]

Perhaps I'm going about this completely the wrong way. Nevertheless I hope the reader understands what I'm trying to accomplish and can suggest a solution.

  • $\begingroup$ Try changing myListPlot[data_, opts_] to myListPlot[data_, opts___]. $\endgroup$ – rafalc Feb 20 at 14:50
  • $\begingroup$ Works like a charm. Why not go ahead and make it an answer. $\endgroup$ – Tom Feb 20 at 14:51

If you want to constrain it to only options from ListPlot, you could use OptionsPattern in combination with FilterRulesand Options.

myListPlot[data_, opts : OptionsPattern[]] := 
 ListPlot[data, GridLines -> {None, {data[[1]]}}, 
  FilterRules[{opts}, Options[ListPlot]]]

which results in:

myListPlot[data, PlotStyle -> Red, Joined -> True]

Mathematica graphics

  • $\begingroup$ OptionsPattern[ListPlot] is more precise. $\endgroup$ – Edmund Feb 20 at 23:06

The usual way to define a Wolfram Language function that takes n arguments and an arbitrary number of options is like this:

f[arg1_, ..., argn_, opts___] := ...

A little bit of pattern matching background (taken from the WL reference):

  • _ any single expression
  • x_ any single expression, to be named x
  • __ any sequence of one or more expressions
  • x__ sequence named x
  • x__h sequence of expressions, all of whose heads are h
  • ___ any sequence of zero or more expressions
  • x___ sequence of zero or more expressions named x
  • x___h sequence of zero or more expressions, all of whose heads are h

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