Modify cylc graph but only in first year

Cylc Cylc Support
1

Note that this similar ish to this question.

I’ve got a suite with this graph statement…

postproc{{ '_atmos' if SPLIT_PP else '' }}[-{{FMT}}] => retrieve_ozone => redistribute_ozone => coupled & rose_arch_ozone

… however I need the *ozone tasks to be ignored in the first year (1850), where 1 year may be multiple cycle points.

I’ve tried this…

          THISYEAR = $(rose date -c -f %Y)
          graph = """
          {% if THISYEAR == 1850 %}
              postproc{{ '_atmos' if SPLIT_PP else '' }}[-{{FMT}}] => coupled
          {%else%}
              postproc{{ '_atmos' if SPLIT_PP else '' }}[-{{FMT}}] => retrieve_ozone => redistribute_ozone => coupled & rose_arch_ozone
          {% endif%}
                  """

… but I get this error…

[FAIL] Jinja2Error:
[FAIL]   File "/home/williamsjh/cylc-run/u-cb503/site/niwa_cray.rc", line 292, in top-level template code
[FAIL]     {% if THISYEAR == 1850 %}
[FAIL] UndefinedError: 'THISYEAR' is undefined

Any ideas how to implement this?

Thanks!

2

Hi Jonny,

Greetings from the Cook Strait Ferry bar :beers:

Firstly, the Jinja2 UndefinedError is because you didn’t define THISYEAR as a Jinja2 variable. All Jinja2 code has to be enclosed in the appropriate curly braces, e.g.: {% set AUSPICIOUS_YEAR = 1969 %}.

Secondly, however, if I understand your problem, you want the graph structure to change 1 year into the workflow. You can’t use Jinja2 to achieve that because Jinja2 is a template processor that we use to programmatically generate the workflow configuration before the scheduler starts up (the template is the suite.rc file with embedded Jinja2 code; the result is plain suite.rc syntax generated by processing the template with Jinja2). So JInja2 never sees “the current cycle point” for a task - that is a runtime concept.

Instead, use Cylc’s cycling graph syntax to generate a graph that is different in the first year. E.g. (you can run this to see how it works):

[cylc]
  cycle point format = %Y%m%d
[scheduling]
  initial cycle point = 1850
  [[dependencies]]
     [[[R/^/P1M]]]
         # Run cheese every month from initial cycle point...
         graph = cheese
     [[[R/^+P1Y/P1M]]]
         # ...but after the first year, make cheese wait on toast.
         graph = toast => cheese
[runtime]
   [[root]]
      script = sleep 10

Hilary

1 Like
3

nice :smiley:

Thanks a lot for the info, very helpful.

I’ve subsequently realised that (I think) the solution should be even simpler than this.

This is the bit of the site file which I have inherited…

[scheduling]
   [[dependencies]]
      [[[ 0101T/P1Y ]]]
         graph = """
postproc{{ '_atmos' if SPLIT_PP else '' }}[-{{FMT}}] => retrieve_ozone => redistribute_ozone => coupled & rose_arch_ozone
 """

So this modifies the graph in the suite.rc only on cycle points that start on January 1st. In this suite the resubmission period is 3 months.

Referring back to the other ticket and specifically Oliver Saunders’ reply I think all I need to do is this…

[scheduling]
   [[dependencies]]
      [[[ 0101T/P1Y!^ ]]]
         graph = """
postproc{{ '_atmos' if SPLIT_PP else '' }}[-{{FMT}}] => retrieve_ozone => redistribute_ozone => coupled & rose_arch_ozone
 """

… where ! is ‘not equal to’ and ^ is the first cycle point.

Let me know if you disagree!

Cheers

Jonny

4

Yep, that’s another way to do it. !^ excludes only the initial point, but that graph section only applies at the start of each year, so :+1:

1 Like
5

thanks hilary. this solution is working well! cheers, j