Hello, Cyclus! [Python]

This pages walks you through a very simple hello world example using Cyclus agents. First make sure that you have the dependencies installed, namely Cyclus and a recent version of Python (2.7 or 3.5+).

Cyclus can read agents from any normal python package and module. If you are unsure of how to start and install a Python project, please see the Python documentation. There are also many high-quality guides and tools online. Here, we will assume that there is a project called proj that has a module called agents that contains an archetype class called MyFacility.

To start writing MyFacility, open up agents.py, import cyclus.agents, anf write the following:

proj/agents.py:

from cyclus.agents import Facility

class MyFacility(Facility):
    """My first Cyclus archetype!"""

And that is it! The above is a fully-functional Cyclus facility.


Let’s now change the behavior of the MyFacility’s tick() and tock() methods to print “Hello” and “World” respectively.

proj/agents.py:

from cyclus.agents import Facility

class MyFacility(Facility):
    """My first Cyclus archetype!"""

    def tick(self):
        print("Hello,")

    def tock(self):
        print("World!")

Now that we have altered the behavior of the TutorialFacility, reinstall the project so that it is available to cyclus.


You can refer to this facilty in a Cyclus input file by using the Python package and module name in the lib section of the archetypes spec, like you would write it if you were importing a module. The class name goes in the name section of the spec.

<archetypes>
  <spec><lib>proj.agents</lib><name>MyFacility</name></spec>
</archetypes>

Let’s run Cyclus with this example! In the input directory there is an example.xml. First modify it to point to the archetype we just wrote. Running Cyclus on this file with the command cyclus input/example.xml should produce the following output.

tutorial $ cyclus input/example.xml
              :
          .CL:CC CC             _Q     _Q  _Q_Q    _Q    _Q              _Q
        CC;CCCCCCCC:C;         /_\)   /_\)/_/\\)  /_\)  /_\)            /_\)
        CCCCCCCCCCCCCl       __O|/O___O|/O_OO|/O__O|/O__O|/O____________O|/O__
     CCCCCCf     iCCCLCC     /////////////////////////////////////////////////
     iCCCt  ;;;;;.  CCCC
    CCCC  ;;;;;;;;;. CClL.                          c
   CCCC ,;;       ;;: CCCC  ;                   : CCCCi
    CCC ;;         ;;  CC   ;;:                CCC`   `C;
  lCCC ;;              CCCC  ;;;:             :CC .;;. C;   ;    :   ;  :;;
  CCCC ;.              CCCC    ;;;,           CC ;    ; Ci  ;    :   ;  :  ;
   iCC :;               CC       ;;;,        ;C ;       CC  ;    :   ; .
  CCCi ;;               CCC        ;;;.      .C ;       tf  ;    :   ;  ;.
  CCC  ;;               CCC          ;;;;;;; fC :       lC  ;    :   ;    ;:
   iCf ;;               CC         :;;:      tC ;       CC  ;    :   ;     ;
  fCCC :;              LCCf      ;;;:         LC :.  ,: C   ;    ;   ; ;   ;
  CCCC  ;;             CCCC    ;;;:           CCi `;;` CC.  ;;;; :;.;.  ; ,;
    CCl ;;             CC    ;;;;              CCC    CCL
   tCCC  ;;        ;; CCCL  ;;;                  tCCCCC.
    CCCC  ;;     :;; CCCCf  ;                     ,L
     lCCC   ;;;;;;  CCCL
     CCCCCC  :;;  fCCCCC
      . CCCC     CCCC .
       .CCCCCCCCCCCCCi
          iCCCCCLCf
           .  C. ,
              :
Hello,
World!
Hello,
World!
Hello,
World!
Hello,
World!
Hello,
World!
Hello,
World!
Hello,
World!
Hello,
World!
Hello,
World!
Hello,
World!

Status: Cyclus run successful!
Output location: cyclus.sqlite
Simulation ID: 0ae730e0-a9a8-4576-afaa-d1db6399d5a2

If you look in the input file you’ll see that the simulation duration was set to 10. This is why “Hello, World!” is printed ten times.