Get =#+RESULTS= without re-evaluating source code block?

Get =#+RESULTS= without re-evaluating source code block?

[doltes]

Get =#+RESULTS= without re-evaluating source code block?

Let's suppose I have a code block which requires a long time to finish

#+NAME: big-computation
#+begin_src bash
sleep 5 # Some computation which requires a long time to complete.
echo a
#+end_src

#+RESULTS: big-computation
#+begin_example
a
#+end_example

I want to use the results of that code block in other code blocks so I
use a =noweb= reference (see below.)

#+begin_src bash :noweb yes
printf "%s\n" <<big-computation()>>
#+end_src

#+RESULTS:
#+begin_example
a

#+end_example

However, doing this (i.e. using a =noweb= reference) would make the
command to be evaluated whenever getting its results. I don't want
this, I want the =:noweb= reference to actually use the already
computed results.

So, my question is: Is it possible to use the actual =#+RESULTS= code
block instead of always evaluating it when referencing the results
through a =:noweb= reference?

-- 
Greetings,
doltes.

Re: Get =#+RESULTS= without re-evaluating source code block?

[tomas]

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On Wed, Jan 27, 2021 at 05:14:43PM -0500, doltes wrote:
> Get =#+RESULTS= without re-evaluating source code block?
> 
> Let's suppose I have a code block which requires a long time to finish
> 
> #+NAME: big-computation
> #+begin_src bash
> sleep 5 # Some computation which requires a long time to complete.
> echo a
> #+end_src
> 
> #+RESULTS: big-computation
> #+begin_example
> a
> #+end_example
> 
> I want to use the results of that code block in other code blocks so I
> use a =noweb= reference (see below.)
> 
> #+begin_src bash :noweb yes
> printf "%s\n" <<big-computation()>>
> #+end_src
> 
> #+RESULTS:
> #+begin_example
> a
> 
> #+end_example
> 
> However, doing this (i.e. using a =noweb= reference) would make the
> command to be evaluated whenever getting its results. I don't want
> this, I want the =:noweb= reference to actually use the already
> computed results.
> 
> So, my question is: Is it possible to use the actual =#+RESULTS= code
> block instead of always evaluating it when referencing the results
> through a =:noweb= reference?

Perhaps "Cache results of evaluation" (15.5 Evaluating Code Blocks,
in the Interwebs here [1] is for you.

In short, add a header argument :cache yes to your code block.

Cheers

[1] https://orgmode.org/org.html#Evaluating-Code-Blocks

 - t

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Re: Get =#+RESULTS= without re-evaluating source code block?

[John Kitchin]

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I tried this but it did not work for me.


On Wed, Jan 27, 2021 at 5:38 PM <tomas@tuxteam.de> wrote:

> On Wed, Jan 27, 2021 at 05:14:43PM -0500, doltes wrote:
> > Get =#+RESULTS= without re-evaluating source code block?
> >
> > Let's suppose I have a code block which requires a long time to finish
> >
> > #+NAME: big-computation
> > #+begin_src bash
> > sleep 5 # Some computation which requires a long time to complete.
> > echo a
> > #+end_src
> >
> > #+RESULTS: big-computation
> > #+begin_example
> > a
> > #+end_example
> >
> > I want to use the results of that code block in other code blocks so I
> > use a =noweb= reference (see below.)
> >
> > #+begin_src bash :noweb yes
> > printf "%s\n" <<big-computation()>>
> > #+end_src
> >
> > #+RESULTS:
> > #+begin_example
> > a
> >
> > #+end_example
> >
> > However, doing this (i.e. using a =noweb= reference) would make the
> > command to be evaluated whenever getting its results. I don't want
> > this, I want the =:noweb= reference to actually use the already
> > computed results.
> >
> > So, my question is: Is it possible to use the actual =#+RESULTS= code
> > block instead of always evaluating it when referencing the results
> > through a =:noweb= reference?
>
> Perhaps "Cache results of evaluation" (15.5 Evaluating Code Blocks,
> in the Interwebs here [1] is for you.
>
> In short, add a header argument :cache yes to your code block.
>
> Cheers
>
> [1] https://orgmode.org/org.html#Evaluating-Code-Blocks
>
>  - t
>
-- 
John

-----------------------------------
Professor John Kitchin
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu

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Re: Get =#+RESULTS= without re-evaluating source code block?

[Greg Minshall]

John,

> I tried this but it did not work for me.

to be clear, caching means that the *first* time you execute, your
reference will have to wait for the long-running computation to
complete, but not during subsequent executions (unless the source block
that performs the execution changes, in which case the reference will
again have to wait).

also, caching means that, after the first execution (ditto caveat) the
source block *will no longer run*.  so, if there were any (other) side
effects of running that source block, they will not happen.  (you could
possibly split the side effect-producing code out of that block.)

i'm not sure if this explains what did not work for you.

cheers, Greg

> 
> 
> On Wed, Jan 27, 2021 at 5:38 PM <tomas@tuxteam.de> wrote:
> 
> > On Wed, Jan 27, 2021 at 05:14:43PM -0500, doltes wrote:
> > > Get =#+RESULTS= without re-evaluating source code block?
> > >
> > > Let's suppose I have a code block which requires a long time to finish
> > >
> > > #+NAME: big-computation
> > > #+begin_src bash
> > > sleep 5 # Some computation which requires a long time to complete.
> > > echo a
> > > #+end_src
> > >
> > > #+RESULTS: big-computation
> > > #+begin_example
> > > a
> > > #+end_example
> > >
> > > I want to use the results of that code block in other code blocks so I
> > > use a =noweb= reference (see below.)
> > >
> > > #+begin_src bash :noweb yes
> > > printf "%s\n" <<big-computation()>>
> > > #+end_src
> > >
> > > #+RESULTS:
> > > #+begin_example
> > > a
> > >
> > > #+end_example
> > >
> > > However, doing this (i.e. using a =noweb= reference) would make the
> > > command to be evaluated whenever getting its results. I don't want
> > > this, I want the =:noweb= reference to actually use the already
> > > computed results.
> > >
> > > So, my question is: Is it possible to use the actual =#+RESULTS= code
> > > block instead of always evaluating it when referencing the results
> > > through a =:noweb= reference?
> >
> > Perhaps "Cache results of evaluation" (15.5 Evaluating Code Blocks,
> > in the Interwebs here [1] is for you.
> >
> > In short, add a header argument :cache yes to your code block.
> >
> > Cheers
> >
> > [1] https://orgmode.org/org.html#Evaluating-Code-Blocks
> >
> >  - t
> >
> -- 
> John
> 
> -----------------------------------
> Professor John Kitchin
> Doherty Hall A207F
> Department of Chemical Engineering
> Carnegie Mellon University
> Pittsburgh, PA 15213
> 412-268-7803
> @johnkitchin
> http://kitchingroup.cheme.cmu.edu

Re: Get =#+RESULTS= without re-evaluating source code block?

[John Kitchin]

I discovered that it matters a lot which block you cache. You have to
cache the long running block. I had put cache on the block with noweb
expansion, and then the long running block still runs every time. That
was a surprise to me, since nothing was changing in that block, so I
thought it would just use the cached result.


Greg Minshall <minshall@umich.edu> writes:

> John,
>
>> I tried this but it did not work for me.
>
> to be clear, caching means that the *first* time you execute, your
> reference will have to wait for the long-running computation to
> complete, but not during subsequent executions (unless the source block
> that performs the execution changes, in which case the reference will
> again have to wait).
>
> also, caching means that, after the first execution (ditto caveat) the
> source block *will no longer run*.  so, if there were any (other) side
> effects of running that source block, they will not happen.  (you could
> possibly split the side effect-producing code out of that block.)
>
> i'm not sure if this explains what did not work for you.
>
> cheers, Greg
>
>>
>>
>> On Wed, Jan 27, 2021 at 5:38 PM <tomas@tuxteam.de> wrote:
>>
>> > On Wed, Jan 27, 2021 at 05:14:43PM -0500, doltes wrote:
>> > > Get =#+RESULTS= without re-evaluating source code block?
>> > >
>> > > Let's suppose I have a code block which requires a long time to finish
>> > >
>> > > #+NAME: big-computation
>> > > #+begin_src bash
>> > > sleep 5 # Some computation which requires a long time to complete.
>> > > echo a
>> > > #+end_src
>> > >
>> > > #+RESULTS: big-computation
>> > > #+begin_example
>> > > a
>> > > #+end_example
>> > >
>> > > I want to use the results of that code block in other code blocks so I
>> > > use a =noweb= reference (see below.)
>> > >
>> > > #+begin_src bash :noweb yes
>> > > printf "%s\n" <<big-computation()>>
>> > > #+end_src
>> > >
>> > > #+RESULTS:
>> > > #+begin_example
>> > > a
>> > >
>> > > #+end_example
>> > >
>> > > However, doing this (i.e. using a =noweb= reference) would make the
>> > > command to be evaluated whenever getting its results. I don't want
>> > > this, I want the =:noweb= reference to actually use the already
>> > > computed results.
>> > >
>> > > So, my question is: Is it possible to use the actual =#+RESULTS= code
>> > > block instead of always evaluating it when referencing the results
>> > > through a =:noweb= reference?
>> >
>> > Perhaps "Cache results of evaluation" (15.5 Evaluating Code Blocks,
>> > in the Interwebs here [1] is for you.
>> >
>> > In short, add a header argument :cache yes to your code block.
>> >
>> > Cheers
>> >
>> > [1] https://orgmode.org/org.html#Evaluating-Code-Blocks
>> >
>> >  - t
>> >
>> --
>> John
>>
>> -----------------------------------
>> Professor John Kitchin
>> Doherty Hall A207F
>> Department of Chemical Engineering
>> Carnegie Mellon University
>> Pittsburgh, PA 15213
>> 412-268-7803
>> @johnkitchin
>> http://kitchingroup.cheme.cmu.edu


--
Professor John Kitchin
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu

Re: Get =#+RESULTS= without re-evaluating source code block?

[Nick Dokos]

John Kitchin <jkitchin@andrew.cmu.edu> writes:

> I discovered that it matters a lot which block you cache. You have to
> cache the long running block. I had put cache on the block with noweb
> expansion, and then the long running block still runs every time. That
> was a surprise to me, since nothing was changing in that block, so I
> thought it would just use the cached result.
>

Just to elaborate a bit: Org mode checks whether to reevaluate a cached block
by checksumming it and seeing if the sum is different from before. That's why
you have to mark the actual block for caching, not its callers.

-- 
Nick

"There are only two hard problems in computer science: cache
invalidation, naming things, and off-by-one errors." -Martin Fowler

Re: Get =#+RESULTS= without re-evaluating source code block?

[doltes]

Yes, it worked like a charm!

Thanks!

tomas@tuxteam.de writes:

> On Wed, Jan 27, 2021 at 05:14:43PM -0500, doltes wrote:
>> Get =#+RESULTS= without re-evaluating source code block?
>> 
>> Let's suppose I have a code block which requires a long time to finish
>> 
>> #+NAME: big-computation
>> #+begin_src bash
>> sleep 5 # Some computation which requires a long time to complete.
>> echo a
>> #+end_src
>> 
>> #+RESULTS: big-computation
>> #+begin_example
>> a
>> #+end_example
>> 
>> I want to use the results of that code block in other code blocks so I
>> use a =noweb= reference (see below.)
>> 
>> #+begin_src bash :noweb yes
>> printf "%s\n" <<big-computation()>>
>> #+end_src
>> 
>> #+RESULTS:
>> #+begin_example
>> a
>> 
>> #+end_example
>> 
>> However, doing this (i.e. using a =noweb= reference) would make the
>> command to be evaluated whenever getting its results. I don't want
>> this, I want the =:noweb= reference to actually use the already
>> computed results.
>> 
>> So, my question is: Is it possible to use the actual =#+RESULTS= code
>> block instead of always evaluating it when referencing the results
>> through a =:noweb= reference?
>
> Perhaps "Cache results of evaluation" (15.5 Evaluating Code Blocks,
> in the Interwebs here [1] is for you.
>
> In short, add a header argument :cache yes to your code block.
>
> Cheers
>
> [1] https://orgmode.org/org.html#Evaluating-Code-Blocks
>
>  - t


-- 
Greetings,
doltes.