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Suppose I have a list:
my_list
where 3 'up's of the list are red(I've made it to Cell Expression as follows).

Cell[BoxData[
RowBox[{"{", 
RowBox[{StyleBox["up", StripOnInput -> False, 
   LineColor -> RGBColor[1, 0, 0], 
   FrontFaceColor -> RGBColor[1, 0, 0], 
   BackFaceColor -> RGBColor[1, 0, 0], 
   GraphicsColor -> RGBColor[1, 0, 0], 
   FontColor -> RGBColor[1, 0, 0]], ",", "right", ",", "up", ",", 
  StyleBox["up", StripOnInput -> False, 
   LineColor -> RGBColor[1, 0, 0], 
   FrontFaceColor -> RGBColor[1, 0, 0], 
   BackFaceColor -> RGBColor[1, 0, 0], 
   GraphicsColor -> RGBColor[1, 0, 0], 
   FontColor -> RGBColor[1, 0, 0]], ",", "down", ",", "down", ",",
   StyleBox["up", StripOnInput -> False, 
   LineColor -> RGBColor[1, 0, 0], 
   FrontFaceColor -> RGBColor[1, 0, 0], 
   BackFaceColor -> RGBColor[1, 0, 0], 
   GraphicsColor -> RGBColor[1, 0, 0], 
   FontColor -> RGBColor[1, 0, 0]], ",", "right", ",", "down", 
  ",", "left"}], "}"}]], "Output", 
CellChangeTimes -> {3.6183594862091923`*^9}]

Then, how can I pick out those elements with style red? Or more, with a specific style?
I tried to use Select[list, Style[#,Red] &] and Cases[list, Style[#,Red] &], but yield nothing.
Thank you!

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1 Answer 1

7
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For your specific example. Assigining it to test.

The InputForm:

InputForm[test]

is

{Style[up, LineColor -> RGBColor[1, 0, 0], FrontFaceColor -> RGBColor[1, 0, 0], BackFaceColor -> RGBColor[1, 0, 0], GraphicsColor -> RGBColor[1, 0, 0], FontColor -> RGBColor[1, 0, 0]], right, up, Style[up, LineColor -> RGBColor[1, 0, 0], FrontFaceColor -> RGBColor[1, 0, 0], BackFaceColor -> RGBColor[1, 0, 0], GraphicsColor -> RGBColor[1, 0, 0], FontColor -> RGBColor[1, 0, 0]], down, down, Style[up, LineColor -> RGBColor[1, 0, 0], FrontFaceColor -> RGBColor[1, 0, 0], BackFaceColor -> RGBColor[1, 0, 0], GraphicsColor -> RGBColor[1, 0, 0], FontColor -> RGBColor[1, 0, 0]], right, down, left}

So for this example you can extract the desired elements:

Cases[test, Style[__]]

Or get their positions (which may be an aim) and extract:

pos = Position[test, Style[__]]
Extract[test, pos]
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2
  • $\begingroup$ I seem to understand. Those 'up's' style are more complex than just a Red, so I have to use BlankSequence? $\endgroup$
    – Ryan
    Commented Aug 30, 2014 at 6:35
  • 2
    $\begingroup$ Nice ... +1 ... could also use Cases[test, _Style]? $\endgroup$
    – kglr
    Commented Aug 30, 2014 at 15:07

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