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Topic: R: R: ReplacePart -> eliminate
Replies: 4   Last Post: Sep 19, 2013 1:14 AM

 Messages: [ Previous | Next ]
 Brambilla Roberto Luigi (RSE) Posts: 25 Registered: 2/21/12
R: R: ReplacePart -> eliminate
Posted: Sep 18, 2013 6:12 AM

Many thanks Bob!

I find great

Cases[y, {_?NumericQ ..}]

Since it works both with simple list and couple list.

What the meaning of .. operator?

Roberto

Da: Bob Hanlon [mailto:hanlonr357@gmail.com]
Inviato: mercoled=EC 18 settembre 2013 04:41
A: Brambilla Roberto Luigi (RSE)
Cc: MathGroup
Oggetto: Re: R: ReplacePart -> eliminate

y = Table[{n, 1/(3 - n)}, {n, 0, 5}] // Quiet

{{0, 1/3}, {1, 1/2}, {2, 1},
{3, ComplexInfinity},
{4, -1}, {5, -(1/2)}}

Note that your crtiteria in the Select does not produce a straight True or False

{NumberQ[#], NumberQ[#]} &[{2, 1}]

{False, False}

num = Select[y, And @@ NumericQ /@ # &]

{{0, 1/3}, {1, 1/2}, {2, 1},
{4, -1}, {5, -(1/2)}}

However, Cases is a better choice here

num ==
Cases[y, _?(And @@ NumericQ /@ # &)] ==
Cases[y, {_?NumericQ, _?NumericQ}] ==
Cases[y, {_?NumericQ ..}]

True

Bob Hanlon

On Tue, Sep 17, 2013 at 9:36 PM, Brambilla Roberto Luigi (RSE) <Roberto.Brambilla@rse-web.it> wrote:

Great!
Many thanks Alexei!
Now I have the following list of couples

y = Table[{n, 1/(3 - n)}, {n, 0, 5}]

{{0, 1/3}, {1, 1/2}, {2, 1}, {3, ComplexInfinity}, {4, -1}, {5, -(1/2)}}

The command

Select[y, {NumberQ[#], NumberQ[#]} &]

does not work. How can I modify your suggestion in order to eliminate the non-numerical couple {3,ComplexInfinity}
from the list (avoiding Transpose etc..)?

Rob.

-----Messaggio originale-----
Da: Alexei Boulbitch [mailto:Alexei.Boulbitch@iee.lu]
Inviato: marted=EC 17 settembre 2013 09:09
A: mathgroup@smc.vnet.net
Cc: Brambilla Roberto Luigi (RSE)
Oggetto: Re: ReplacePart -> eliminate

I'd like to eliminate the Indeterminate (or other non-numerical terms, as Infinite, etc...) items. Es.

x = {-1.25664, 0.628319, -0.628319, 1.25664, Indeterminate, -1.25664,
0.628319, -0.628319, 1.25664, Indeterminate};

or

x=Table[1/(3 - n), {n, 0, 5}])
{1/3, 1/2, 1, ComplexInfinity, -1,-1/2}

How can I do it with a simple command?
Many thanks, Roberto

Hi, Roberto,

Try this:

x = {-1.25664, 0.628319, -0.628319, 1.25664, Indeterminate, -1.25664,
0.628319, -0.628319, 1.25664, Indeterminate}; y = Table[1/(3 - n), {n, 0, 5}];

Select[x, NumberQ[#] &]
Select[y, NumberQ[#] &]

{-1.25664, 0.628319, -0.628319, 1.25664, -1.25664, 0.628319, \ -0.628319, 1.25664}

{1/3, 1/2, 1, -1, -(1/2)}

Have fun, Alexei

Alexei BOULBITCH, Dr., habil.
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Date Subject Author
9/18/13 Brambilla Roberto Luigi (RSE)
9/18/13 Bob Hanlon
9/19/13 Bob Hanlon