PyPlot ArgumentError: haskey of NULL PyObject error

[Kai Xin Thia]

Using the sample code below, Version 0.4.3 on Mac, I keep getting the error. Is there a way to fix it?:

using PyPlot

n = 50

srand(1)

x = rand(n)

y = rand(n)

area = pi .* (15 .* rand(n)).^2 # 0 to 15 point radiuses

scatter(x, y, s=area, alpha=0.5)

LoadError: ArgumentError: haskey of NULL PyObject

while loading In[12], in expression starting on line 8

 in haskey at /Users/admin/.julia/v0.4/PyCall/src/PyCall.jl:249

 in scatter at /Users/admin/.julia/v0.4/PyPlot/src/PyPlot.jl:457

For reference, Pkg.status()

4 required packages:

 - IJulia                        1.1.8

 - Plots                         0.5.2

 - PyCall                        1.4.0              master

 - PyPlot                        2.1.1

17 additional packages:

 - BinDeps                       0.3.21

 - ColorTypes                    0.2.1

 - Colors                        0.6.3

 - Compat                        0.7.12

 - Conda                         0.1.9

 - Dates                         0.4.4

 - FixedPointNumbers             0.1.2

 - Homebrew                      0.2.0

 - JSON                          0.5.0

 - LaTeXStrings                  0.1.6

 - MacroTools                    0.3.0

 - Nettle                        0.2.2

 - Reexport                      0.0.3

 - Requires                      0.2.2

 - SHA                           0.1.2

 - URIParser                     0.1.2

 - ZMQ                           0.3.1 

[Josef Heinen]

Works find on my machines. Does you example work in the Python environment you are using within Julia?

[cdm]

this also works on JuliaBox, https://www.juliabox.org/, although with the 0.4 and 0.5 kernels,

users will need to add the PyPlot package themselves ...

result:

In [9]:

scatter(x, y, s=area, alpha=0.5)

Out[9]:

PyObject <matplotlib.collections.PathCollection object at 0x7ff61063aa90>

[Steven G. Johnson]

It sounds like "using PyPlot" probably threw an error that you ignored?

To make sure that Python and Matplotlib are properly installed, the easiest thing is to have PyCall install its own Miniconda Python distro:

     ENV["PYTHON"]=""

     Pkg.build("PyCall")

You only need to do this once, then re-launch Julia "using PyPlot" will install Matplotlib if needed.