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Re: Re: Color coding a Table entry

  • To: mathgroup at
  • Subject: [mg92702] Re: [mg92688] Re: Color coding a Table entry
  • From: Bob Hanlon <hanlonr at>
  • Date: Sat, 11 Oct 2008 06:42:07 -0400 (EDT)
  • Reply-to: hanlonr at

For plots use ColorFunction

Plot[(x - 1) (x - 4), {x, 0, 5}, 
 ColorFunction -> Function[{x, y}, If[y < 0, Blue, Red]],
 ColorFunctionScaling -> False]

Bob Hanlon

---- AES <siegman at> wrote: 

Original post:

> I'm Printing (to the screen) a Table like, let's say,
>    Table[{f1, f2, f3}, (x, xmin, xmax}]
> and anytime the value of f2 goes negative I want that value printed in 
> Red.   What's a simple, compact way to code this?

Of the dozen or so replies, I'd say that

> Table[{f1, Style[f2, If[f2 < 0, Red, Black]], f3}, {x, -1, 5}]
> Bob Hanlon

is by far the best:  simple, clean, you can see what it does, no arcane 
symbols, no cross effects on anything else outside that entry (and, the 
solution I'd already come up with on my own).

If the conditional in the If[ ] statement got lengthy, to avoid 
cluttering up the Table with it I might go to the alternative suggestion

>     redneg[expr_] := If[cond[expr], Style[expr, Red], expr, expr]
>     With[{xmin = 0, xmax = 10},
<      Table[{f1, redneg[f2], f3}, {x, xmin, xmax}]]
>  Regards, Jean-Marc

Or, just define the conditional separately, outside the Table,

   cond[expr_] : = <<something>>

and use

        Style[f2, If[fcond[f2], Red, Black]]

in the Table.

Would  Plot[redneg[f[x]], {x, xmin, xmax}]  make the plot turn black 
below the x axis???   Have to try it and see . . .


Bob Hanlon

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