Wolfram Mathematica

3:31 AM

@Mr.Wizard @R.M. @J.M. @TimStone For your information:

0

Q: Feature Request: Please update the Wolfram Language highlighter for this site

I took the time to update the Google-prettify highlighter for Mathematica to the current version 11.0.1. The whole project can be found in my Mathematica Source Code Highlighting repository on GitHub, but the only important file that changed is lang-mma.min.js (un-minified source file lang-mma....

feature-request

Meta

8:34 AM

0

Q: Should we cull content in community wiki omnibus Q&A's?

I fear that omnibus Q&A's (is there an accepted term for these?) like What are the most common pitfalls awaiting new users? and Where can I find examples of good Mathematica programming practice? can grow too long to be genuinely useful, and they may have done so already. When one is met with a ...

discussion site-organization community-wiki

yode

10:10 AM

Sorry my English,what's meaning of your "Leonid's streams" here

@WReach

And how do you know the Read is the analog of Python's next?

J. M.

10:36 AM

@yode, he prolly meant this.

JasonB

2:37 PM

1

Q: How to add second, linearly rescaled X-axis on the top frame, using version 9?

From data test, I want to plot a graph with two x axes (see the image which I have added). Two $x$ axes, one at bottom and other on top. In test data, test[[1 ;; All, 1]] is $x$-axis at bottom, test[[1 ;; All, 2]] is $y$-axis and test[[1 ;; All, 3]] is $x$-axis at top. With my code, second $x$-ax...

plotting

This question was marked as a duplicate, and it may have been one, but the answer in the marked duplicate wasn't working for OP. I reopened it just to give an answer, but if someone cares to remark as a dupe, by all means do so.

I do feel like there hasn't been a good example of how to use Charting`FindTicks effectively, so this answer will be of help.

WReach

6:55 PM

@J.M. @yode Yes, that's what I meant by "Leonid's streams".

yode

@WReach Thanks a lot.（ping J.M.）

WReach

@yode I call Read the analog of Python's generator next by example:

Needs["GeneralUtilities`"]

$i = RangeIterator[2];
Read[$i] (* 1 *)
Read[$i] (* 2 *)
Read[$i] (* IteratorExhausted *)

yode

After Read one time,the i will be 1 from 0.Do you know how to reset it to 0?

@WReach

i = GeneralUtilities`RangeIterator[3]

WReach

@yode To get the example back to zero we need to create a new RangeIterator. While it is possible that a particular iterator implementation might provide some sort of "reset" operation, it is not a common practice. Iterators, by nature, are stateful and not replayable.

yode

This is current method I have get just now.

GeneralUtilitiesIteratorsPackagePrivate`getIteratorSymbols[i]

But I don't know how to get the variable of Iteratorsi$46137`

WReach

7:12 PM

@yode I would strongly discourage that practice. You are reaching into internal implementation details that may change between releases. Also, it requires a detailed analysis of the implementation to assess whether such forceful state modification has unforeseen consequences. Finally, it violates the concept of "iterator".

yode

WReach

@yode ... and to illustrate my point, in my version of Mathematica getIteratorSymbols does not exist -- it is getIteratorState which returns both the symbols and their values:

yode

Oh~,My version is

WReach

@yode Me too, but I am guessing that we have different versions of the GeneralUtilities` paclet.

yode

And do you know GeneralUtilities`DelegateIterator and GeneralUtilities`IteratorGraph?

WReach

7:26 PM

@yode I have not looked at them.

Yet ;)

yode

You mean the paclet will affect that?Well,first time to know it.

WReach

@yode Yes. Once I was quite surprised to watch the behaviour of a particular dataset operation change after I closed and re-opened Mathematica. By chance, a paclet update had arrived between the two times that I opened the application. This was back in the early 10.x days.

@yode IteratorGraph visualizes a particular composition of iterators:

JoinIterator[RangeIterator[10], ConstantIterator[99]] // IteratorGraph

yode

Wow,thanks~

yode

8:31 PM

@WReach I'm not very understand your this answer

It's seem we must use Scope when we use UnpackOptions?

It's seem this two case is equivalent?

WReach

8:59 PM

@yode Macro expansion is only triggered if the outermost head on the right-hand-side of a definition is a macro. Inner macros do not work. So, for example, this will not work:

Options[f] = {A->10,B->20};
f[x_, OptionsPattern[]] := Module[{a, b}, UnpackOptions[a, b]; {x, a, b}]

f[1]
(* {1,a$676,b$676} *)

If we were to replace Module with Scope, then the outermost head would be a macro and expansion would occur:

f[x_, OptionsPattern[]] := Scope[UnpackOptions[a, b]; {x, a, b}]

f[1]
(* {1,10,20} *)

If we don't want to use Scope, there is a handy no-op macro called UseMacros:

f[x_, OptionsPattern[]] := UseMacros@Module[{a, b}, UnpackOptions[a, b]; {x, a, b}]

f[1]
(* {1,10,20} *)

Macros are restricted in this way because they are implemented as up-values on Set and family.

yode

I finally see it.:)

@WReach Thanks.

andre

@WReach You said :"By chance, a paclet update had arrived between the two times that I opened the application". Do you remember how you discovered that a new paclet had arrived ?

I'm asking because of this

WReach

9:15 PM

@yode I updated my response to include this information.

@andre A paclet update may occur whenever you see a pop-up message claiming to be downloading content from Wolfram servers. I didn't figure out about the paclet update until it happened a few more times and I read some comments from WRI personnel talking about the "weekly paclet bug update" (I don't remember where I read those comments.)

We can check the version of any given paclet thus:

PacletFind["GeneralUtilities"] // PacletInformation //
  GeneralUtilities`ToAssociations // Dataset

PackletFind[] will list all paclets.

yode

@WReach And in your answer,you use a function MXBatchIterator.We can use it to build a iterator,like

But I can Read it

Read and GeneralUtilities`PackageScope`PullIterator will fail to get element as I try

WReach

@yode It's official: you spend more time in undocumented code than me ;D I've never used MXBatchIterator and I'd never even heard of MXNetLink until it turned up in a text search when I was looking for usages of UnpackOptions (which I had never heard of until I read your question).

Having said that, I can see from looking at the definition of MXBatchIterator that it is expecting the association to have a non-trivial internal structure. Presumably some intermediate result having to do with "deep learning" operations. It is not happy with the keys having simple atomic values.

Transcript for