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getting number of prop values from array

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  getting number of prop values from array Andrew Poulos <ap_prog@hotmail.com> - 2019-02-15 19:44 +1100
    Re: getting number of prop values from array "R.Wieser" <address@not.available> - 2019-02-15 10:15 +0100
    Re: getting number of prop values from array Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2019-02-15 15:08 +0100
      Re: getting number of prop values from array Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2019-02-15 15:16 +0100
        Re: getting number of prop values from array Andrew Poulos <ap_prog@hotmail.com> - 2019-02-16 14:11 +1100
      Re: getting number of prop values from array John G Harris <niam@jghnorth.org.uk.invalid> - 2019-02-16 15:37 +0000
        Re: getting number of prop values from array Julio Di Egidio <julio@diegidio.name> - 2019-02-16 10:43 -0800
          Re: getting number of prop values from array Andrew Poulos <ap_prog@hotmail.com> - 2019-02-17 12:50 +1100
            Re: getting number of prop values from array Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2019-02-17 16:23 +0100
              Re: getting number of prop values from array Julio Di Egidio <julio@diegidio.name> - 2019-02-17 15:41 -0800
            Re: getting number of prop values from array Julio Di Egidio <julio@diegidio.name> - 2019-02-17 16:08 -0800
              Re: getting number of prop values from array Andrew Poulos <ap_prog@hotmail.com> - 2019-02-18 11:32 +1100
                Re: getting number of prop values from array Julio Di Egidio <julio@diegidio.name> - 2019-02-17 22:13 -0800
                  Re: getting number of prop values from array Andrew Poulos <ap_prog@hotmail.com> - 2019-02-18 19:56 +1100
                    Re: getting number of prop values from array Julio Di Egidio <julio@diegidio.name> - 2019-02-18 01:24 -0800
                      Re: getting number of prop values from array Andrew Poulos <ap_prog@hotmail.com> - 2019-02-18 20:36 +1100
        Re: getting number of prop values from array "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2019-02-19 19:15 -0800
    Re: getting number of prop values from array Mickey Finn <mfinney@gmail.com> - 2019-02-17 13:42 -0300
    Re: getting number of prop values from array dr.j.r.stockton@gmail.com - 2019-02-26 07:43 -0800

#36020 — getting number of prop values from array

If I have an object that looks like this

{
   "links": [
     {
       "from": "1ff9fce8",
       "to": "2cc8ebd7",
       "id": "1a8d67fe"
     },
     {
       "from": "2cc8ebd7",
       "to": "8d1d8c2b",
       "id": "f4ca15f5"
     },
     {
       "from": "2cc8ebd7",
       "to": "4c48567f",
       "id": "9384e250"
     },
     {
       "from": "8d1d8c2b",
       "to": "9e2e9d3c",
       "id": "12c2b1b4"
     },
     {
       "from": "2cc8ebd7",
       "to": "324db009",
       "id": "8c348628"
     },
     {
       "from": "4c48567f",
       "to": "9e2e9d3c",
       "id": "2cbe2766"
     },
     {
       "from": "324db009",
       "to": "9e2e9d3c",
       "id": "e715fe9f"
     },
     ...
   ]
}

how can I make a list of the number of times a 'from' value that appears 
more than once appears?

In the example above "2cc8ebd7" appears as 'from' 3 times. I've got some 
code with nested for loops that sort of works but I'm struggling to work 
out a more robust way.

Andrew Poulos

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#36021

Andrew,

> how can I make a list of the number of times a 'from' value that appears 
> more than once appears?

My first thought is to create an associative array (directory object ?), and 
put the values of the "from"s into it as keys, with an associated value of 
1.  When the key already exists just increment the associated value.

After having done that you can iterate that associative array for any value 
thats not 1.

Regards,
Rudy Wieser

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#36022

Andrew Poulos wrote:
> If I have an object that looks like this
> 
> {
>    "links": [
>      {
>        "from": "1ff9fce8",
>        "to": "2cc8ebd7",
>        "id": "1a8d67fe"
>      },
>      {
>        "from": "2cc8ebd7",
>        "to": "8d1d8c2b",
>        "id": "f4ca15f5"
>      },
>      {
>        "from": "2cc8ebd7",
>        "to": "4c48567f",
>        "id": "9384e250"
>      },
>      // […]
>    ]
> }
> 
> how can I make a list of the number of times a 'from' value that appears 
> more than once appears?
> 
> In the example above "2cc8ebd7" appears as 'from' 3 times. I've got some 
> code with nested for loops that sort of works but I'm struggling to work 
> out a more robust way.

  var obj = {
    links: [
      {
        "from": "1ff9fce8",
        "to": "2cc8ebd7",
        "id": "1a8d67fe"
      },
      {
        "from": "2cc8ebd7",
        "to": "8d1d8c2b",
        "id": "f4ca15f5"
      },
      {
        "from": "2cc8ebd7",
        "to": "4c48567f",
        "id": "9384e250"
      }
    ]
  };

  var stats = Object.create(null);

  obj.links.forEach((item) => {
    var from = item.from;
    stats[from] = ((from in stats) ? stats[from] + 1 : 1);
  });

  /* {1ff9fce8: 1, 2cc8ebd7: 2} */
  console.log(stats);

Replace “var” with “let” or “const” in production-quality code (unless it
must be backwards-compatible to ES < 6 and you are not using a transpiler,
in which case you must replace the other expressions as well).

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#36023

Thomas 'PointedEars' Lahn wrote:
> […]
>   var stats = Object.create(null);
> 
>   obj.links.forEach((item) => {
>     var from = item.from;
>     stats[from] = ((from in stats) ? stats[from] + 1 : 1);
>   });
> 
>   /* {1ff9fce8: 1, 2cc8ebd7: 2} */
>   console.log(stats);

  /* [{from: "2cc8ebd7", count: 2}] */
  console.log(
    Object.keys(stats)
      .map((from) => ({from: from, count: stats[from]}))
      .filter((item) => (item.count > 1))
  );
> Replace “var” with “let” or “const” in production-quality code (unless it
> must be backwards-compatible to ES < 6 and you are not using a transpiler,
> in which case you must replace the other expressions as well).

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#36024

On 16/02/2019 1:16 am, Thomas 'PointedEars' Lahn wrote:
> Thomas 'PointedEars' Lahn wrote:
>> […]
>>    var stats = Object.create(null);
>>
>>    obj.links.forEach((item) => {
>>      var from = item.from;
>>      stats[from] = ((from in stats) ? stats[from] + 1 : 1);
>>    });
>>
>>    /* {1ff9fce8: 1, 2cc8ebd7: 2} */
>>    console.log(stats);
> 
>    /* [{from: "2cc8ebd7", count: 2}] */
>    console.log(
>      Object.keys(stats)
>        .map((from) => ({from: from, count: stats[from]}))
>        .filter((item) => (item.count > 1))
>    );
>> Replace “var” with “let” or “const” in production-quality code (unless it
>> must be backwards-compatible to ES < 6 and you are not using a transpiler,
>> in which case you must replace the other expressions as well).

Thanks, it's short, easy enough for me to parse, and gives me exactly 
the result I needed.

Andrew Poulos

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#36025

On Fri, 15 Feb 2019 15:08:27 +0100, Thomas 'PointedEars' Lahn
<PointedEars@web.de> wrote:

  <snip>
>Replace “var” with “let” or “const” in production-quality code (unless it
>must be backwards-compatible to ES < 6 and you are not using a transpiler,
>in which case you must replace the other expressions as well).

Also, you can't create an object with an empty prototype chain if
using ES < 5. 

  John

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#36026

On Saturday, 16 February 2019 16:37:10 UTC+1, John G Harris  wrote:
> On Fri, 15 Feb 2019 15:08:27 +0100, Thomas 'PointedEars' Lahn
> <PointedEars@web.de> wrote:
>   <snip>
> >Replace “var” with “let” or “const” in production-quality code (unless it
> >must be backwards-compatible to ES < 6 and you are not using a transpiler,
> >in which case you must replace the other expressions as well).
> 
> Also, you can't create an object with an empty prototype chain if
> using ES < 5. 

FWIW, I'd give the exact opposite advice: there is actually no sensible reason
on earth to use any JS stuff past ES5, all they have done past that point is
messing the language up.

Julio

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#36027

On 17/02/2019 5:43 am, Julio Di Egidio wrote:

> FWIW, I'd give the exact opposite advice: there is actually no sensible reason
> on earth to use any JS stuff past ES5, all they have done past that point is
> messing the language up.

I realise that you probably know more about ES than I do. Still this
<http://exploringjs.com/es6/ch_overviews.html>
looks good. What is messing up the language?

Andrew Poulos

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#36028

Andrew Poulos wrote:
> On 17/02/2019 5:43 am, Julio Di Egidio wrote:
>> FWIW, I'd give the exact opposite advice: there is actually no sensible reason
>> on earth to use any JS stuff past ES5, all they have done past that point is
>> messing the language up.
> 
> I realise that you probably know more about ES than I do.

Your realization is wrong.  The records shows that Julio Di Egidio is just a
wannabe and a troll; he has a big mouth and no clue.

> Still this
> <http://exploringjs.com/es6/ch_overviews.html>
> looks good. What is messing up the language?

Nothing.  Do not feed the troll.

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#36030

On Sunday, 17 February 2019 16:23:23 UTC+1, Thomas 'PointedEars' Lahn  wrote:

> The records shows that Julio Di Egidio is just a
> wannabe and a troll; he has a big mouth and no clue.

You are a fraud and disgrace for this arena.

But no pearls for swine, keep guessing...

*Plonk*

Julio

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#36031

[Restored context: the resident troll and moron must exposed.]
On Saturday, 16 February 2019 16:37:10 UTC+1, John G Harris  wrote: 
> On Fri, 15 Feb 2019 15:08:27 +0100, Thomas 'PointedEars' Lahn 
> <PointedEars@web.de> wrote: 
>   <snip> 
> >Replace “var” with “let” or “const” in production-quality code (unless it 
> >must be backwards-compatible to ES < 6 and you are not using a transpiler, 
> >in which case you must replace the other expressions as well). 
> 
> Also, you can't create an object with an empty prototype chain if 
> using ES < 5. 

On Sunday, 17 February 2019 02:50:49 UTC+1, Andrew Poulos  wrote:
> On 17/02/2019 5:43 am, Julio Di Egidio wrote:
> 
> > FWIW, I'd give the exact opposite advice: there is actually no sensible reason
> > on earth to use any JS stuff past ES5, all they have done past that point is
> > messing the language up.
> 
> I realise that you probably know more about ES than I do. Still this
> <http://exploringjs.com/es6/ch_overviews.html>
> looks good. What is messing up the language?

Looks good by which standard, you utter moron?  Rather learn to use question
marks honestly, MORON.

And take note: I don't give a shit about teaching the unteachable...

*Plonk*

Julio

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#36032

On 18/02/2019 11:08 am, Julio Di Egidio wrote:

> And take note: I don't give a shit about teaching the unteachable...

Ha ha ha, repeating what your teachers told you.

Andrew Poulos

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#36033

On Monday, 18 February 2019 01:32:09 UTC+1, Andrew Poulos  wrote:
> On 18/02/2019 11:08 am, Julio Di Egidio wrote:
> 
> > And take note: I don't give a shit about teaching the unteachable...
> 
> Ha ha ha, repeating what your teachers told you.

Hahaha, how old are you, 6?  Laugh at your lack of integrity, you stupid fuck.

That said, a thread about how to do a loop?!  You stupid fucks must be truly
retarded...

Julio

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#36034

On 18/02/2019 5:13 pm, Julio Di Egidio wrote:

> That said, a thread about how to do a loop?!  You stupid fucks must be truly
> retarded...

Don't hold back. Let everyone know what kind of person you really are 
(just in case there's someone with any doubt).

Andrew Poulos

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#36035

On Monday, 18 February 2019 09:56:58 UTC+1, Andrew Poulos  wrote:
> On 18/02/2019 5:13 pm, Julio Di Egidio wrote:
> 
> > That said, a thread about how to do a loop?!  You stupid fucks must be truly
> > retarded...
> 
> Don't hold back. Let everyone know what kind of person you really are 
> (just in case there's someone with any doubt).

Everyone who, you delusional moron and patent troll who can't even really
google stuff up, you and the other resident trolls??  This group is rather
dead thanks to you resident fucks.  Why don't you all just migrate to SO
for good??  Indeed, why don't you get another hobby, say, in agriculture?

(EOD.)

*Plonk*

Julio

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#36036

On 18/02/2019 8:24 pm, Julio Di Egidio wrote:

> *Plonk*

If you are describing yourself the correct term is *Plonker*.

Andrew Poulos

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#36040

John G Harris wrote:
> Also, you can't create an object with an empty prototype chain if
> using ES < 5. 

Unless you abuse the host environment in some way. For example, across an iframe boundary: 

<https://stackoverflow.com/a/36117912/153209>

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#36029

Andrew Poulos wrote:
> If I have an object that looks like this
> 
> {
>    "links": [
>      {
>        "from": "1ff9fce8",
>        "to": "2cc8ebd7",
>        "id": "1a8d67fe"
>      },
>      {
>        "from": "2cc8ebd7",
>        "to": "8d1d8c2b",
>        "id": "f4ca15f5"
>      },
>      {
>        "from": "2cc8ebd7",
>        "to": "4c48567f",
>        "id": "9384e250"
>      },
>      {
>        "from": "8d1d8c2b",
>        "to": "9e2e9d3c",
>        "id": "12c2b1b4"
>      },
>      {
>        "from": "2cc8ebd7",
>        "to": "324db009",
>        "id": "8c348628"
>      },
>      {
>        "from": "4c48567f",
>        "to": "9e2e9d3c",
>        "id": "2cbe2766"
>      },
>      {
>        "from": "324db009",
>        "to": "9e2e9d3c",
>        "id": "e715fe9f"
>      },
>      ...
>    ]
> }
> 
> how can I make a list of the number of times a 'from' value that appears 
> more than once appears?
> 
> In the example above "2cc8ebd7" appears as 'from' 3 times. I've got some 
> code with nested for loops that sort of works but I'm struggling to work 
> out a more robust way.

var o = {
   "links": [
     {
       "from": "1ff9fce8",
       "to": "2cc8ebd7",
       "id": "1a8d67fe"
     },
     /* etc. */
   ]
};

var a = o.links;
var b = a.map(x => x.from);
var c = b.reduce((a, c) => a.set(c, 1 + (a.get(c) || 0)), new Map());
console.log(c);

//Yields a Map():
{"1ff9fce8" => 1, "2cc8ebd7" => 3, "8d1d8c2b" => 1, "4c48567f" => 1, 
"324db009" => 1}

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#36060

On Friday, 15 February 2019 08:44:43 UTC, Andrew Poulos wrote:
> If I have an object that looks like this

> ...

> how can I make a list of the number of times a 'from' value that appears 
> more than once appears?

Firstly :

The FIRST thing to do is to consider just who, and what software, will be running your code.

If this is a private HTML page just for you, your current browser, and your current OS, then anything which works for that will do - though you should write in a subset of HTML which you can comfortably read.

If it is for a knowable group of fellow-employees, for example, you need to be somewhat more careful.

If it is for the Web, more careful than that.  And so on.

For example, I have J[ava]Script which can be used at a Windows command line with CScript, which cannot sensibly be used _as_is_ with WScript, and can also be used as an include file by a .HTA - for all of those it must be JScript-compatible.  It can also be used by a modern standard browser, so HTML5 applies; but it must also be easily readable by me, so it must as far as practical be HTML3.

J[ava]Script can be embedded in a system which is not primarily a computer as such - e.g. a router, a measuring instrument, a car, a satellite ...

Code to be used non-commercially by myself and friends should be moderately foolproof, but not necessarily idiot-proof; but code for commercial use on the Web needs to be bullet-proof.

And so on.

So you need to say something about the circumstances under which the code may be run, at least to show that you have thought about that.


Secondly:

Your shown values are all strings of eight characters representing hexadecimal digits; there *might* be advantage in using 32-bit unsigned integers instead.


Thirdly:

I have for some years now been storing (local, relative) Windows file names as the identifiers of properties of an ordinary object, with the data being the mere existence of a property or additionally its integer value - and that is very like what has already been suggested here.  It works exactly as hoped for, in CScript and in Firefox.  Tests seem to show that it works also with strings which could not be such names - but I've not tested all possible strings.

-- 
  (c) John Stockton, near London, UK.  Using Google Groups.           |
 Mail: J.R.""""""""@physics.org - or as Reply-To, if any.             |

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