Error: Command '['dot', '-V']' returned non-zero exit status -5 When using Iris

Question

After I installed the package Iris with conda install -c scitools iris,

Whether using Ipython console or Jupyter notebook, the iris was always failed to import. The error subroutine shows like:

 ---------------------------------------------------------------------------
CalledProcessError                        Traceback (most recent call last)
<ipython-input-1-005053b25f37> in <module>()
----> 1 import iris

/Users/TEST/anaconda/lib/python2.7/site-packages/iris/__init__.pyc in <module>()
    110 import iris.cube
    111 import iris._constraints
--> 112 import iris.fileformats
    113 import iris.io
    114 

/Users/TEST/anaconda/lib/python2.7/site-packages/iris/fileformats/__init__.py in <module>()
     23 from six.moves import (filter, input, map, range, zip)  # noqa
     24 
---> 25 from iris.io.format_picker import (FileExtension, FormatAgent,
     26                                    FormatSpecification, MagicNumber,
     27                                    UriProtocol, LeadingLine)

/Users/TEST/anaconda/lib/python2.7/site-packages/iris/io/__init__.py in <module>()
     31 
     32 import iris.fileformats
---> 33 import iris.fileformats.dot
     34 import iris.cube
     35 import iris.exceptions

/Users/TEST/anaconda/lib/python2.7/site-packages/iris/fileformats/dot.py in <module>()
     41             # Check PATH
     42             subprocess.check_output([_DOT_EXECUTABLE_PATH, '-V'],
---> 43                                     stderr=subprocess.STDOUT)
     44         except OSError:
     45             _DOT_EXECUTABLE_PATH = None

/Users/TEST/anaconda/lib/python2.7/subprocess.pyc in check_output(*popenargs, **kwargs)
    571         if cmd is None:
    572             cmd = popenargs[0]
--> 573         raise CalledProcessError(retcode, cmd, output=output)
    574     return output
    575 

CalledProcessError: Command '['dot', '-V']' returned non-zero exit status -5

Answer 1

I raised a similar issue on the iris GitHub tracker (https://github.com/SciTools/iris/issues/1899). Essentially, as much as I believe it was intended to be optional, the way it has been implemented I think Iris actually requires a dot installation. With conda, that should look like:

conda install graphviz

HTH