Cannot index GridSpec array

[berceanu]

I am trying to adapt this matplotlib demo to Julia: http://matplotlib.org/users/plotting/examples/demo_gridspec03.py. I have this so far

using PyPlot
using PyCall
@pyimport matplotlib.gridspec as gspec

fig = plt.figure()

gs1 = gspec.GridSpec(1, 1)
gs1[:update](top=1.0, bottom=0.84)
ax1 = plt.subplot(gs1[0, 0])

gs2 = gspec.GridSpec(2, 1)
gs2[:update](top=0.77, bottom=0.44, hspace=0.0)
ax2 = plt.subplot(gs2[0, 0])
ax3 = plt.subplot(gs2[1, 0])

gs3 = gspec.GridSpec(2, 1)
gs3[:update](top=0.38, bottom=0.0, hspace=0.4)
ax4 = plt.subplot(gs3[0, 0])
ax5 = plt.subplot(gs3[1, 0])

fig[:savefig]("../../figures/gridspec.pdf")
plt.close(fig)

and I get
ERROR: getindex has no method matching getindex(::PyObject, ::Int64, ::Int64).
Apparently I cannot access a particular element of the grid like gs1[0,0].

[stevengj]

See the PyCall README: The biggest diffence from Python is that object attributes/members are accessed with o[:attribute] rather than o.attribute, and you use get(o, key) rather than o[key]. (This is because Julia does not permit overloading the . operator yet.)

Instead of gs[i,j], do get(gs, (i,j)).

fig = plt.figure()

gs1 = gspec.GridSpec(1, 1)
gs1[:update](top=1.0, bottom=0.84)
ax1 = plt.subplot(get(gs1, (0, 0)))

gs2 = gspec.GridSpec(2, 1)
gs2[:update](top=0.77, bottom=0.44, hspace=0.0)
ax2 = plt.subplot(get(gs2, (0, 0)))
ax3 = plt.subplot(get(gs2, (1, 0)))

gs3 = gspec.GridSpec(2, 1)
gs3[:update](top=0.38, bottom=0.0, hspace=0.4)
ax4 = plt.subplot(get(gs3, (0, 0)))
ax5 = plt.subplot(get(gs3, (1, 0)))

[stevengj]

Maybe I should implement object[Integer...], however, for the common case of an integer-indexed (or tuple-of-integer-indexed) sequence like this.

[berceanu]

Thanks. Indeed, that sounds like a good idea, if it's not too much work :)

[berceanu]

On a further note, how does one index ranges, like ax = plt.subplot(get(gs, (0, 0:2))). This currently produces an error.

[stevengj]

good question … I have no idea how Python represents this. (Once you know what underlying Python object is passed to the object[...] method, making it in Julia is easy.)

[stevengj]

Aha, they are implemented by slice objects in Python: https://docs.python.org/2/library/functions.html#slice

[stevengj]

So, you can do pycall(pybuiltin("slice"), PyObject, 0,2) to pass 0:2.

(Cumbersome, I know, but you could write a slice wrapper function for this.)

[pranaymodukuru]

So, you can do pycall(pybuiltin("slice"), PyObject, 0,2) to pass 0:2.

(Cumbersome, I know, but you could write a slice wrapper function for this.)

Could you please give an example for wrapper function.

[ajwheeler]

slice(i,j) = pycall(pybuiltin("slice"), PyObject, i,j)