ImportError("No module named 'matplotlib'",)

I complied Julia under Archlinux. Successfully added PyPlot package, but failed in loading it:

```
julia> using(PyPlot)
ERROR: PyError (PyImport_ImportModule)
ImportError("No module named 'matplotlib'",)

in pyerr_check at /home/hellolj/.julia/PyCall/src/exception.jl:58
in pyimport at /home/hellolj/.julia/PyCall/src/PyCall.jl:85
in reload_path at loading.jl:146
in _require at loading.jl:59
in require at loading.jl:43
while loading /home/hellolj/.julia/PyPlot/src/PyPlot.jl, in expression starting on line 32
```

I suspect that this error happened because under Arch Linux, ipython 2.7 is named ipython2 insteady of ipython by default on Julia side.

Can anyone help with this issue?

Thanks,

Start at PyPlot/src/PyPlot.jl line 32 and follow the PyCall import path through PyCall/src/PyCall.jl and exception.jl. Reproduce the failure under Arch Linux while checking how Python, IPython, and matplotlib are discovered. Done means the cause of the missing matplotlib import is identified and a working loading path is validated.

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