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Re: A Question About Directive

  • To: mathgroup at smc.vnet.net
  • Subject: [mg111236] Re: A Question About Directive
  • From: "Kevin J. McCann" <Kevin.McCann at umbc.edu>
  • Date: Sat, 24 Jul 2010 05:08:56 -0400 (EDT)
  • References: <i2btei$bff$1@smc.vnet.net>

I remain unconvinced. As I said earlier, I don't think that the examples 
I have seen do much more than replace the extra wiggly brackets, "{}", 
with more keystrokes "Directive[]". I don't find it easier to read.

My original post was not to say that the examples you show are not 
valid, I just wondered if the folks at Wolfram went to the trouble of 
defining a new function for more than just that.

As far as Total goes, that is much more intuitive than Plus @@, but the 
use of the word Directive, at least to me, is not intuitive and requires 
that I look it up in the Help.


Kevin

Murray Eisenberg wrote:
> Good example! Of course one _could_ still dispense with Directive in the 
> first one, using instead...
> 
>    Plot[{Cos[x], Sin[x]}, {x, 0, 2 Pi}, PlotStyle -> {{Thick, Red}}]
> 
> ... with the nested PlotStyle value. And here, too, the point is that 
> Directive provides a convenience of eliminating nested braces.
> 
> Just because a function such as Directive in such situations is a mere 
> convenience and not indispensable does not militate against its 
> existence. After all, some other newer functions such as Total or 
> Accumulate are also dispensable but nonetheless conveniences.
> 
> If you want to stick with fewer functions, just go ahead and use the 
> nested parentheses.
> 
> On 7/22/2010 5:42 AM, Mark McClure wrote:
>> On Mon, Jul 19, 2010 at 2:10 AM, Kevin J. McCann<kjm at kevinmccann.com>  wrote:
>>> I have noticed the use of Directive in some of the graphics examples
>>> from Bob Hanlon, David Park, and others. I am curious about this
>>> command, since it does not appear to do much that is new.
>>> ...
>>> So, what is the benefit of Directive?
>> Try
>> Plot[{Cos[x], Sin[x]}, {x, 0, 2 Pi},
>>   PlotStyle ->  Directive[Thick, Red]]
>> vs
>> Plot[{Cos[x], Sin[x]}, {x, 0, 2 Pi},
>>   PlotStyle ->  List[Thick, Red]]
>>
>> Mark McClure
>>
> 


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