       Re: Plotting just specific points

• To: mathgroup at smc.vnet.net
• Subject: [mg54119] Re: Plotting just specific points
• Date: Fri, 11 Feb 2005 03:33:30 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```On 2/9/05 at 9:27 AM, chocolatez at gmail.com (zak) wrote:

>if i have the list: a={5,1,2,2,6,7,2,2,8,2} and in the ListPlot[a]
>i want to show only the points wich represent only the "2" while
>preserving the positions of the "2" in the list, so i could focus
>my attention to a specific wanted values, how could i do that

a = {5, 1, 2, 2, 6, 7, 2, 2, 8, 2};
ListPlot[Select[Transpose@{Range@Length@a, a}, Last@# == 2&]];

>or even better if it is possible to plot the whole values of
>ListPlot[a] while making the points "2" in red color as an example.

b = Transpose@{Range@Length@a, a};
Show[
Block[{\$DisplayFunction = Identity},
{ListPlot[Select[b, Last@# != 2&]],
ListPlot[Select[b, Last@#1 == 2&],
PlotStyle -> {PointSize[0.015], Hue}]}]];

And there are many other variations on these. For example, I could have constructed b in the code above as:

b = MapIndexed[Flatten@{#2,#1}&,a]

or

or I could use LabeledListPlot or MultipleListPlot in the Graphics add ons. For example,

<< "Graphics`";
LabeledListPlot[