Wolfram Mathematica - 2012-10-14

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Mathematica StackExchange (meta)

3:32 AM

1

Q: What happens to SE images on Imgur that we post but don't use?

I use the SE Uploader palette to upload images, eg: http://i.stack.imgur.com/jncBA.png. I'm going to upload a different image. Can we remove something we put up? Do we need to worry about that?

3 hours later…

Gustavo Bandeira

6:05 AM

@F'x This reminded me of you.

6:23 AM

@halirutan and it is ok to change from Count[{nb,#]&/@ {1,2}, in Count[{nb,#]&/@ {0,1}?

6:37 AM

@GustavoBandeira hi

Gustavo Bandeira

@F'x I remeber of talking about that with you. =)

I have thought since our discussion

Gustavo Bandeira

About what?

I came to a somewhat weird conclusion: if you want to make a positive contribution in many persons' lives, you probably should become a meteorologist or something :)

there's heavy math (and computation) involved, it's a very young field still, and it does impact the whole society

Gustavo Bandeira

@F'x Yep. I have a kind of passion for AI's - which are quite the oposite, they'll destroy our world.

6:42 AM

@GustavoBandeira destroy our world? not so sure :) obligatory xkcd reference: what-if.xkcd.com/5

Gustavo Bandeira

@F'x Yep, I imagined it. I was just making a joke on the common sense about AI's - but this text is interesting, thanks for it.

2 hours later…

8:25 AM

In[154]:= FixedPoint[evaluateAll, A]

During evaluation of In[154]:= ArrayPad::arr: First argument A to ArrayPad should be an array. >>

Out[154]= {}

Do you know why??

2 hours later…

9:59 AM

hello; could you please confirm the following (input) bug? In mathematica, lets say I want to input in a text cell ${f_x}_y$ in mathematica. The problem I run into is when I try to input the second subscript, mathematica jumps from Traditional form to InputForm and most annoyingly the Undo command does not work.

Does anyone know how to compute an exponential moving average for the following vector: I have a vector of 1 and 0 and I want to attribute an exponential weight: i can use the formula Exponential Moving Average, the problem is that in this way there is a mistake. I want to differentiate the moving average in the following way:
If number in the vector is 0, then ExponentialMovingAverage[vector,0.06];
If number in the vector is 1, the ExponentialMovingAverage[vector,0.94];

May some one help me??

3 hours later…

1:01 PM

l = RandomInteger[{0, 1}, 4];
MapIndexed[#1 /. \[FormalY] :> If[l[[#2[[1]]]] > 0, 94/100, 6/100] &,
ExponentialMovingAverage[l, \[FormalY]]]

1:26 PM

Also

@DanieleRicci MapIndexed[#1 /. \[FormalY] :> 22/25 l[[#2[[1]]]] + 3/50 &, ExponentialMovingAverage[l, \[FormalY]]]

Ok, to make it clear: We change the colors to Black = 0, White = 1 and Blue = 2. We change the meaning too! Blue is now the **neutral state** which is reached, when we have `numBlack==numWhite`.
With this definition you want to count the number of Black (0) and White (1) cells in the neighborhood. Therefore, `Count[nb, #] & /@ {0, 1}` is correct. Let me give a full working example:

countBlackWhite[a_, i_, j_] :=
  With[{nb = Flatten@a[[i - 1 ;; i + 1, j - 1 ;; j + 1]]},
   Count[nb, #] & /@ {0, 1}];
evaluateCell[a_, i_, j_] :=
 Module[{numBlack, numWhite}, {numBlack, numWhite} =
   countBlackWhite[a, i, j];
  Which[numBlack == numWhite, 2, numWhite > numBlack, 1, True, 0]]
evaluateAll[A_] :=
 With[{paddedA = ArrayPad[A, 1]},
  Table[evaluateCell[paddedA, i, j], {i, 2, Length[A] + 1}, {j, 2,
    Length[A[[1]]] + 1}]]
makeFrames[A_] :=
  Map[ArrayPlot[#, Mesh -> False,
     ColorFunction ->

Please see note the ColorFunction inside ArrayPlot:

ColorFunction ->
 Function[{cell},
  Which[cell === 0, Black, cell === 1, White, cell === 2, Blue]

To make this work, you have to turn off the scaling of the values inside ArrayPlot by setting ColorFunctionScaling -> False

With the above definitions, the example works:

data = RandomInteger[2, {100, 100}];
animate[makeFrames[data]]

user image

7 hours later…

8:12 PM

@chris You here?

8:34 PM

@belisarius yes; sorry I was answering a question!

@chris Hi! It's Ok!

Do you have a few minutes to try?

sure.

thanks

ok open a new Mma session (just t be sure)

open a new nb

and exucute this

@belisarius done.

NotebookPut@ImportString[Uncompress@FromCharacterCode@Flatten@ImageData[Import@ "http://i.stack.imgur.com/hjjsf.png","Byte"],"NB"]

8:36 PM

@belisarius done

Ok Did it open a new nb?

@belisarius yes

Ok. Execute the code there

it produces a button

Ok!

wait

user image

8:39 PM

yes. Ah !

do you see a new palette?

it did something new... produced a small pallette

ok

now create a new notebook

and write something in there

like a plot

ok

done?

8:40 PM

yes

ok

now

without loosing focus on that new notebook, click on the palette button

then

close all your notebooks, and create a new one

done

paste your clipboard contents here (in the chat)

NotebookPut@
ImportString[
Uncompress@
FromCharacterCode@
Flatten@ImageData[Import@"http://i.stack.imgur.com/hjjsf.png",
"Byte"], "NB"] `

wait a moment

8:43 PM

b.t.w. I do get an error message when I press the button

it says in the message window...

stuff... SEnbUploader`stackImage::err: Server returner error: You didn\'t enter a URL

@chris Something is not working

strange

let me check the code

I am assuming you got it to work with other people?

@chris With Sjoerd, yes

ah... I must be doing something wrong unless its an OS or version pb.

I have learnt something though about the buttons ;-)

@chris I am not sure about how to debug it remotely :(

8:47 PM

well does not matter... thanks for trying!

@chris I'll have to wait for Szabolcs .. he is the palette master

If he can set himself free sometime in the future

hi toad!

Too late for that now

Hi

@bel looks like your palette issues are related to connection issues with SE's imgur. See Sz's question on SO answered by Arnoud for more info on that

@rm-rf But I COPIED Szabolc's code :(

Heh, then you suck at copying :)

@rm-rf I'm looking for that question

@rm-rf I'm still looking for something I don't suck at

8:57 PM

I would say "You certainly don't suck at sucking", but I haven't figured out how to say it without it sounding awkward :D

It was his highest voted Q and had the java tag on it. That should narrow it down for you

@rm-rf You're allowed be awkward. You're a toad after all

I found it

1 hour later…

10:23 PM

:6491215 Sure you want to put it here?

Put what here?

@rm-rf Don't know what you're speaking about

:)

Safer way to remove something from chat... any SE mod can read if it is merely deleted. Now only mma mods can read.

I want to change the name for this room... Mathematica seems too plain. How about FrontEnd or $FrontEnd or something else mma related?

<<Chat` might make a good room tagline

Console: where error messages go

?

(I mean, that's my suggestion for the room name)

Might be better if it is something immediately recognizable as mma (granted, frontend is pretty generic too)

Nasser M. Abbasi

10:33 PM

any one here like to try a demonstration CDF? I need to get some feedback on this before I send it to WRI demo project. It is a particles motion simulation. Collision between particles.

11:25 PM

I wonder why someone voted to close this:

2

Q: Excel UI over Mathematica

This is NOT about importing/exporting Excel data to/from Mathematica. This is purely a UI question. The Mathematica notebook interface is very "linear" I type in an INPUT line Mathematic OUTPUT line I'm wondering if there is something like an excel interface for Mathematica. For example, I...

any thoughts?

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