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Posted to dev@tinkerpop.apache.org by Stephen Mallette <sp...@gmail.com> on 2016/02/16 15:13:12 UTC
Gremlin Console Tutorial
We answer a lot of questions on the user mailing list about the Gremlin
Console and there are many themes of usage that seem to come up time and
time again. I figured that these themes would make a good addition as a
tutorial.
http://tinkerpop.apache.org/docs/3.1.1-incubating/tutorials/the-gremlin-console/
I hope you all enjoy this more in-depth look at such an important tool of
the TinkerPop stack.
Stephen
Re: [TinkerPop] Gremlin Console Tutorial
Posted by Marko Rodriguez <ok...@gmail.com>.
I learned from Daniel Kuppitz ---
gremlin> traversal = g.V().out(); []
Looks nicer and doesn't return ==>null.
Marko.
http://markorodriguez.com
On Feb 16, 2016, at 1:05 PM, HadoopMarc <bi...@xs4all.nl> wrote:
>
> Nice to read, indeed!
>
> As an alternative to the weird ";null" line ending to prevent the console iterating, you can also do:
> gremlin> :set max-iteration 0
>
> Cheers, Marc
>
> --
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Re: Gremlin Console Tutorial
Posted by HadoopMarc <bi...@xs4all.nl>.
Nice to read, indeed!
As an alternative to the weird ";null" line ending to prevent the console
iterating, you can also do:
gremlin> :set max-iteration 0
Cheers, Marc
Re: Gremlin Console Tutorial
Posted by Marko Rodriguez <ok...@gmail.com>.
Hi,
This has been sitting in my flag'd inbox for some time. Sorry for the late reply.
> This:
>
> gremlin> t = g.V(1).outE().group().by(label).by(inV());null
> ==>null
> gremlin> t.next()
> ==>created=v[3]
> ==>knows=v[2]
>
> versus the "correct" answer of:
>
> gremlin> g.V(1).outE().group().by(label).by(inV().fold()).next()
> ==>created=[v[3]]
> ==>knows=[v[2], v[4]]
The reduction in group() is called with valueTraversal.next(). If you expect more than one answer, you should fold(). There are a couple of things going on here:
1. There is only one valueTraversal for each key. Meaning, each input is not evaluated separately.
2. If we always assume a fold() at the end, then we are stuck with things like:
gremlin> g.V().group().by(label).by(count())
==>[software:2, person:4]
gremlin> g.V().group().by(label).by(count().fold())
==>[software:[2], person:[4]]
The problem with a forced "fold" is that then users have to do an unfold() to get to their data. Given that group() is about a "key" and a "reduce," the reduction is assumed to be a "single thing" where fold() is actually a reducing barrier step, where that one thing is a list full of many things :).
Hope that is clear,
Marko.
http://markorodriguez.com
>
>
>
>
> On Thu, Feb 25, 2016 at 1:58 PM, Marko Rodriguez <ok...@gmail.com>
> wrote:
>
>> Hi,
>>
>> I don't understand the question. Can you provide a simple example?
>>
>> Thanks,
>> Marko.
>>
>> http://markorodriguez.com
>>
>> On Feb 25, 2016, at 11:54 AM, Jonathan Ellithorpe <jd...@cs.stanford.edu>
>> wrote:
>>
>>> Yup
>>>
>>> On Thu, Feb 25, 2016 at 10:27 AM Stephen Mallette <sp...@gmail.com>
>>> wrote:
>>>
>>>> so your question is: why doesn't the Traversal in the by() iterate
>>>> everything in it rather than requiring the call to fold()?
>>>>
>>>> marko, perhaps you're best suited to answer that....
>>>>
>>>> On Thu, Feb 25, 2016 at 1:17 PM, Jonathan Ellithorpe <
>> jde@cs.stanford.edu>
>>>> wrote:
>>>>
>>>>> Very helpful, thank you. The bits about how the console automatically
>>>>> iterates over the return value was very helpful.
>>>>>
>>>>> One part that was still a little unclear to me was why only next() is
>>>>> called on the inV() Traversal for the second by().
>>>>>
>>>>> "[the console] only iterates the result of a line of execution.
>>>> Therefore,
>>>>> inner Traversal instances do not get that benefit, and as such, inV()
>>>> only
>>>>> has next() called upon it pulling a single vertex from the "knows"
>> edges"
>>>>>
>>>>> That only the returned traversal gets iterated makes sense, but why
>> that
>>>>> iteration doesn't, in its course, trigger a complete iteration of inV()
>>>> is
>>>>> unclear to me.
>>>>>
>>>>> I just started using the gremlin console yesterday so this is all new
>> to
>>>> me
>>>>> :)
>>>>>
>>>>> Jonathan
>>>>>
>>>>> On Wed, Feb 24, 2016 at 12:27 PM Kelvin Lawrence <
>>>>> kelvin.r.lawrence@gmail.com> wrote:
>>>>>
>>>>>> Thanks for putting this together. I recall we had some good exchanges
>>>>> last
>>>>>> year about the good ole console!
>>>>>>
>>>>>>
>>>>>> Kelvin
>>>>>>
>>>>>>
>>>>>> On Tuesday, February 16, 2016 at 8:13:14 AM UTC-6, Stephen Mallette
>>>>> wrote:
>>>>>>>
>>>>>>> We answer a lot of questions on the user mailing list about the
>>>> Gremlin
>>>>>>> Console and there are many themes of usage that seem to come up time
>>>> and
>>>>>>> time again. I figured that these themes would make a good addition
>>>> as a
>>>>>>> tutorial.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>
>>>>
>> http://tinkerpop.apache.org/docs/3.1.1-incubating/tutorials/the-gremlin-console/
>>>>>>>
>>>>>>> I hope you all enjoy this more in-depth look at such an important
>> tool
>>>>> of
>>>>>>> the TinkerPop stack.
>>>>>>>
>>>>>>> Stephen
>>>>>>>
>>>>>>
>>>>>
>>>>
>>
>>
Re: Gremlin Console Tutorial
Posted by Stephen Mallette <sp...@gmail.com>.
This:
gremlin> t = g.V(1).outE().group().by(label).by(inV());null
==>null
gremlin> t.next()
==>created=v[3]
==>knows=v[2]
versus the "correct" answer of:
gremlin> g.V(1).outE().group().by(label).by(inV().fold()).next()
==>created=[v[3]]
==>knows=[v[2], v[4]]
On Thu, Feb 25, 2016 at 1:58 PM, Marko Rodriguez <ok...@gmail.com>
wrote:
> Hi,
>
> I don't understand the question. Can you provide a simple example?
>
> Thanks,
> Marko.
>
> http://markorodriguez.com
>
> On Feb 25, 2016, at 11:54 AM, Jonathan Ellithorpe <jd...@cs.stanford.edu>
> wrote:
>
> > Yup
> >
> > On Thu, Feb 25, 2016 at 10:27 AM Stephen Mallette <sp...@gmail.com>
> > wrote:
> >
> >> so your question is: why doesn't the Traversal in the by() iterate
> >> everything in it rather than requiring the call to fold()?
> >>
> >> marko, perhaps you're best suited to answer that....
> >>
> >> On Thu, Feb 25, 2016 at 1:17 PM, Jonathan Ellithorpe <
> jde@cs.stanford.edu>
> >> wrote:
> >>
> >>> Very helpful, thank you. The bits about how the console automatically
> >>> iterates over the return value was very helpful.
> >>>
> >>> One part that was still a little unclear to me was why only next() is
> >>> called on the inV() Traversal for the second by().
> >>>
> >>> "[the console] only iterates the result of a line of execution.
> >> Therefore,
> >>> inner Traversal instances do not get that benefit, and as such, inV()
> >> only
> >>> has next() called upon it pulling a single vertex from the "knows"
> edges"
> >>>
> >>> That only the returned traversal gets iterated makes sense, but why
> that
> >>> iteration doesn't, in its course, trigger a complete iteration of inV()
> >> is
> >>> unclear to me.
> >>>
> >>> I just started using the gremlin console yesterday so this is all new
> to
> >> me
> >>> :)
> >>>
> >>> Jonathan
> >>>
> >>> On Wed, Feb 24, 2016 at 12:27 PM Kelvin Lawrence <
> >>> kelvin.r.lawrence@gmail.com> wrote:
> >>>
> >>>> Thanks for putting this together. I recall we had some good exchanges
> >>> last
> >>>> year about the good ole console!
> >>>>
> >>>>
> >>>> Kelvin
> >>>>
> >>>>
> >>>> On Tuesday, February 16, 2016 at 8:13:14 AM UTC-6, Stephen Mallette
> >>> wrote:
> >>>>>
> >>>>> We answer a lot of questions on the user mailing list about the
> >> Gremlin
> >>>>> Console and there are many themes of usage that seem to come up time
> >> and
> >>>>> time again. I figured that these themes would make a good addition
> >> as a
> >>>>> tutorial.
> >>>>>
> >>>>>
> >>>>>
> >>>
> >>
> http://tinkerpop.apache.org/docs/3.1.1-incubating/tutorials/the-gremlin-console/
> >>>>>
> >>>>> I hope you all enjoy this more in-depth look at such an important
> tool
> >>> of
> >>>>> the TinkerPop stack.
> >>>>>
> >>>>> Stephen
> >>>>>
> >>>>
> >>>
> >>
>
>
Re: Gremlin Console Tutorial
Posted by Marko Rodriguez <ok...@gmail.com>.
Hi,
I don't understand the question. Can you provide a simple example?
Thanks,
Marko.
http://markorodriguez.com
On Feb 25, 2016, at 11:54 AM, Jonathan Ellithorpe <jd...@cs.stanford.edu> wrote:
> Yup
>
> On Thu, Feb 25, 2016 at 10:27 AM Stephen Mallette <sp...@gmail.com>
> wrote:
>
>> so your question is: why doesn't the Traversal in the by() iterate
>> everything in it rather than requiring the call to fold()?
>>
>> marko, perhaps you're best suited to answer that....
>>
>> On Thu, Feb 25, 2016 at 1:17 PM, Jonathan Ellithorpe <jd...@cs.stanford.edu>
>> wrote:
>>
>>> Very helpful, thank you. The bits about how the console automatically
>>> iterates over the return value was very helpful.
>>>
>>> One part that was still a little unclear to me was why only next() is
>>> called on the inV() Traversal for the second by().
>>>
>>> "[the console] only iterates the result of a line of execution.
>> Therefore,
>>> inner Traversal instances do not get that benefit, and as such, inV()
>> only
>>> has next() called upon it pulling a single vertex from the "knows" edges"
>>>
>>> That only the returned traversal gets iterated makes sense, but why that
>>> iteration doesn't, in its course, trigger a complete iteration of inV()
>> is
>>> unclear to me.
>>>
>>> I just started using the gremlin console yesterday so this is all new to
>> me
>>> :)
>>>
>>> Jonathan
>>>
>>> On Wed, Feb 24, 2016 at 12:27 PM Kelvin Lawrence <
>>> kelvin.r.lawrence@gmail.com> wrote:
>>>
>>>> Thanks for putting this together. I recall we had some good exchanges
>>> last
>>>> year about the good ole console!
>>>>
>>>>
>>>> Kelvin
>>>>
>>>>
>>>> On Tuesday, February 16, 2016 at 8:13:14 AM UTC-6, Stephen Mallette
>>> wrote:
>>>>>
>>>>> We answer a lot of questions on the user mailing list about the
>> Gremlin
>>>>> Console and there are many themes of usage that seem to come up time
>> and
>>>>> time again. I figured that these themes would make a good addition
>> as a
>>>>> tutorial.
>>>>>
>>>>>
>>>>>
>>>
>> http://tinkerpop.apache.org/docs/3.1.1-incubating/tutorials/the-gremlin-console/
>>>>>
>>>>> I hope you all enjoy this more in-depth look at such an important tool
>>> of
>>>>> the TinkerPop stack.
>>>>>
>>>>> Stephen
>>>>>
>>>>
>>>
>>
Re: Gremlin Console Tutorial
Posted by Jonathan Ellithorpe <jd...@cs.stanford.edu>.
Yup
On Thu, Feb 25, 2016 at 10:27 AM Stephen Mallette <sp...@gmail.com>
wrote:
> so your question is: why doesn't the Traversal in the by() iterate
> everything in it rather than requiring the call to fold()?
>
> marko, perhaps you're best suited to answer that....
>
> On Thu, Feb 25, 2016 at 1:17 PM, Jonathan Ellithorpe <jd...@cs.stanford.edu>
> wrote:
>
> > Very helpful, thank you. The bits about how the console automatically
> > iterates over the return value was very helpful.
> >
> > One part that was still a little unclear to me was why only next() is
> > called on the inV() Traversal for the second by().
> >
> > "[the console] only iterates the result of a line of execution.
> Therefore,
> > inner Traversal instances do not get that benefit, and as such, inV()
> only
> > has next() called upon it pulling a single vertex from the "knows" edges"
> >
> > That only the returned traversal gets iterated makes sense, but why that
> > iteration doesn't, in its course, trigger a complete iteration of inV()
> is
> > unclear to me.
> >
> > I just started using the gremlin console yesterday so this is all new to
> me
> > :)
> >
> > Jonathan
> >
> > On Wed, Feb 24, 2016 at 12:27 PM Kelvin Lawrence <
> > kelvin.r.lawrence@gmail.com> wrote:
> >
> > > Thanks for putting this together. I recall we had some good exchanges
> > last
> > > year about the good ole console!
> > >
> > >
> > > Kelvin
> > >
> > >
> > > On Tuesday, February 16, 2016 at 8:13:14 AM UTC-6, Stephen Mallette
> > wrote:
> > >>
> > >> We answer a lot of questions on the user mailing list about the
> Gremlin
> > >> Console and there are many themes of usage that seem to come up time
> and
> > >> time again. I figured that these themes would make a good addition
> as a
> > >> tutorial.
> > >>
> > >>
> > >>
> >
> http://tinkerpop.apache.org/docs/3.1.1-incubating/tutorials/the-gremlin-console/
> > >>
> > >> I hope you all enjoy this more in-depth look at such an important tool
> > of
> > >> the TinkerPop stack.
> > >>
> > >> Stephen
> > >>
> > >
> >
>
Re: Gremlin Console Tutorial
Posted by Stephen Mallette <sp...@gmail.com>.
so your question is: why doesn't the Traversal in the by() iterate
everything in it rather than requiring the call to fold()?
marko, perhaps you're best suited to answer that....
On Thu, Feb 25, 2016 at 1:17 PM, Jonathan Ellithorpe <jd...@cs.stanford.edu>
wrote:
> Very helpful, thank you. The bits about how the console automatically
> iterates over the return value was very helpful.
>
> One part that was still a little unclear to me was why only next() is
> called on the inV() Traversal for the second by().
>
> "[the console] only iterates the result of a line of execution. Therefore,
> inner Traversal instances do not get that benefit, and as such, inV() only
> has next() called upon it pulling a single vertex from the "knows" edges"
>
> That only the returned traversal gets iterated makes sense, but why that
> iteration doesn't, in its course, trigger a complete iteration of inV() is
> unclear to me.
>
> I just started using the gremlin console yesterday so this is all new to me
> :)
>
> Jonathan
>
> On Wed, Feb 24, 2016 at 12:27 PM Kelvin Lawrence <
> kelvin.r.lawrence@gmail.com> wrote:
>
> > Thanks for putting this together. I recall we had some good exchanges
> last
> > year about the good ole console!
> >
> >
> > Kelvin
> >
> >
> > On Tuesday, February 16, 2016 at 8:13:14 AM UTC-6, Stephen Mallette
> wrote:
> >>
> >> We answer a lot of questions on the user mailing list about the Gremlin
> >> Console and there are many themes of usage that seem to come up time and
> >> time again. I figured that these themes would make a good addition as a
> >> tutorial.
> >>
> >>
> >>
> http://tinkerpop.apache.org/docs/3.1.1-incubating/tutorials/the-gremlin-console/
> >>
> >> I hope you all enjoy this more in-depth look at such an important tool
> of
> >> the TinkerPop stack.
> >>
> >> Stephen
> >>
> >
>
Re: Gremlin Console Tutorial
Posted by Jonathan Ellithorpe <jd...@cs.stanford.edu>.
Very helpful, thank you. The bits about how the console automatically
iterates over the return value was very helpful.
One part that was still a little unclear to me was why only next() is
called on the inV() Traversal for the second by().
"[the console] only iterates the result of a line of execution. Therefore,
inner Traversal instances do not get that benefit, and as such, inV() only
has next() called upon it pulling a single vertex from the "knows" edges"
That only the returned traversal gets iterated makes sense, but why that
iteration doesn't, in its course, trigger a complete iteration of inV() is
unclear to me.
I just started using the gremlin console yesterday so this is all new to me
:)
Jonathan
On Wed, Feb 24, 2016 at 12:27 PM Kelvin Lawrence <
kelvin.r.lawrence@gmail.com> wrote:
> Thanks for putting this together. I recall we had some good exchanges last
> year about the good ole console!
>
>
> Kelvin
>
>
> On Tuesday, February 16, 2016 at 8:13:14 AM UTC-6, Stephen Mallette wrote:
>>
>> We answer a lot of questions on the user mailing list about the Gremlin
>> Console and there are many themes of usage that seem to come up time and
>> time again. I figured that these themes would make a good addition as a
>> tutorial.
>>
>>
>> http://tinkerpop.apache.org/docs/3.1.1-incubating/tutorials/the-gremlin-console/
>>
>> I hope you all enjoy this more in-depth look at such an important tool of
>> the TinkerPop stack.
>>
>> Stephen
>>
>
Re: Gremlin Console Tutorial
Posted by Kelvin Lawrence <ke...@gmail.com>.
Thanks for putting this together. I recall we had some good exchanges last
year about the good ole console!
Kelvin
On Tuesday, February 16, 2016 at 8:13:14 AM UTC-6, Stephen Mallette wrote:
>
> We answer a lot of questions on the user mailing list about the Gremlin
> Console and there are many themes of usage that seem to come up time and
> time again. I figured that these themes would make a good addition as a
> tutorial.
>
>
> http://tinkerpop.apache.org/docs/3.1.1-incubating/tutorials/the-gremlin-console/
>
> I hope you all enjoy this more in-depth look at such an important tool of
> the TinkerPop stack.
>
> Stephen
>