change display of matplotlib figures

Author: Christopher Doris

docs/src/compat.md

@@ -20,19 +20,24 @@ In the other direction, the following functions can be used to convert any `Tabl
 pytable
 ```
 
-## MatPlotLib / PyPlot
+## MatPlotLib / PyPlot / Seaborn
 
-```@docs
-pyplot_show
-```
+MatPlotLib figures can be shown with Julia's display mechanism,
+like `display(fig)` or `display(mime, fig)`.
+
+This means that if you return a figure from a Jupyter or Pluto notebook cell,
+it will be shown. You can call `display(plt.gcf())` to display the current figure.
 
-If Julia is running an IJulia kernel, `pyplot_show()` is automatically called after executing a cell, so that plots generated in a cell are always shown (similar to IPython). It can be disabled by setting `PythonCall.CONFIG.auto_pyplot_show = false`.
+We also provide a simple MatPlotLib backend: `mpl.use("module://juliacall.matplotlib")`.
+Now you can call `plt.show()` to display the figure with Julia's display mechanism.
+You can specify the format like `plt.show(format="png")`.
 
 ## GUIs (including MatPlotLib)
 
 ### Event loops
 
-If for example you wish to use PyPlot in interactive mode (`matplotlib.pyplot.ion()`) then activating the correct event loop will allow it to work.
+If for example you wish to use PyPlot in interactive mode (`matplotlib.pyplot.ion()`)
+then activating the correct event loop will allow it to work.
 
 ```@docs
 PythonCall.event_loop_on

examples/seaborn.jl

@@ -5,10 +5,10 @@ using Markdown
 using InteractiveUtils
 
 # ╔═╡ e9dcc3e9-7c0f-40aa-b633-1242aacca66c
-using Pkg; Pkg.activate("tmp", shared=true)
+using Pkg; Pkg.activate("tmp", shared=true);
 
 # ╔═╡ 545b2750-1bc5-11ec-1d6a-275133eec22d
-using PythonCall, RDatasets
+using PythonCall, RDatasets;
 
 # ╔═╡ dbf0b8fc-d9d1-492a-892e-79f1ea86c345
 iris = dataset("datasets", "iris");

juliacall/matplotlib.py

@@ -0,0 +1,34 @@
+"""
+Minimal matplotlib backend which shows plots using Julia's display mechanism.
+"""
+
+from matplotlib.backend_bases import Gcf, FigureManagerBase
+from matplotlib.backends.backend_agg import FigureCanvasAgg
+from juliacall import Base as jl
+
+FigureCanvas = FigureCanvasAgg
+
+def show(format=None):
+    for figmanager in Gcf.get_all_fig_managers():
+        figmanager.show(format=format)
+
+FORMAT_TO_MIME = {
+    'png': 'image/png',
+    'jpg': 'image/jpeg',
+    'jpeg': 'image/jpeg',
+    'tif': 'image/tiff',
+    'tiff': 'image/tiff',
+    'svg': 'image/svg+xml',
+    'pdf': 'application/pdf',
+}
+
+class FigureManager(FigureManagerBase):
+    def show(self, format=None):
+        fig = self.canvas.figure
+        mime = FORMAT_TO_MIME.get(format)
+        if format is None:
+            jl.display(fig)
+        elif mime is None:
+            raise ValueError('invalid format {}, expecting one of: {}'.format(format, ', '.join(FORMAT_TO_MIME.keys())))
+        else:
+            jl.display(mime, fig)

src/PythonCall.jl

@@ -75,7 +75,6 @@ include("compat/with.jl")
 include("compat/multimedia.jl")
 include("compat/serialization.jl")
 include("compat/gui.jl")
-include("compat/matplotlib.jl")
 include("compat/ipython.jl")
 include("compat/tables.jl")
 
@@ -84,7 +83,6 @@ function __init__()
         init_consts()
         init_pyconvert()
         init_datetime()
-        init_pyshow()
         # juliacall/jlwrap
         init_juliacall()
         init_jlwrap_base()
@@ -103,8 +101,8 @@ function __init__()
         init_juliacall_2()
         # compat
         init_stdlib()
+        init_pyshow()
         init_gui()
-        init_matplotlib()
         init_ipython()
         init_tables()
     end

src/compat/matplotlib.jl

@@ -25,15 +25,14 @@ end
 
 ### Particular rules
 
+# x._repr_mimebundle_()
 function pyshow_rule_mimebundle(io::IO, mime::String, x::Py)
     try
         ans = x._repr_mimebundle_(include=pylist((mime,)))
         if pyisinstance(ans, pybuiltins.tuple)
             data = ans[0][mime]
-            meta = ans[1].get(mime)
         else
             data = ans[mime]
-            meta = pybuiltins.None
         end
         write(io, pyconvert(Union{String,Vector{UInt8}}, data))
         return true
@@ -59,17 +58,16 @@ const MIME_TO_REPR_METHOD = Dict(
     "image/svg+xml" => "_repr_svg_",
 )
 
+# x._repr_FORMAT_()
 function pyshow_rule_repr(io::IO, mime::String, x::Py)
     method = get(MIME_TO_REPR_METHOD, mime, "")
     isempty(method) && return false
     try
         ans = pygetattr(x, method)()
         if pyisinstance(ans, pybuiltins.tuple)
             data = ans[0]
-            meta = ans[1]
         else
             data = ans
-            meta = pybuiltins.None
         end
         write(io, pyconvert(Union{String,Vector{UInt8}}, data))
         return true
@@ -90,16 +88,25 @@ const MIME_TO_MATPLOTLIB_FORMAT = Dict(
     "application/pdf" => "pdf",
 )
 
+# x.savefig()
+# Requires x to be a matplotlib.pyplot.Figure, or x.figure to be one.
+# Closes the underlying figure.
 function pyshow_rule_savefig(io::IO, mime::String, x::Py)
-    # TODO: restrict to types or modules which are known to have a savefig method like this?
     format = get(MIME_TO_MATPLOTLIB_FORMAT, mime, "")
     isempty(format) && return false
+    pyhasattr(x, "savefig") || return false
     try
-        # buf = pyimport("io").BytesIO()
-        # x.savefig(buf, format=format)
-        # data = pyconvert(Vector{UInt8}, buf.getvalue())
-        # write(io, data)
-        x.savefig(io, format=format)
+        plt = pysysmodule.modules["matplotlib.pyplot"]
+        Figure = plt.Figure
+        fig = x
+        while !pyisinstance(fig, Figure)
+            fig = fig.figure
+        end
+        buf = pyimport("io").BytesIO()
+        x.savefig(buf, format=format)
+        data = pyconvert(Vector{UInt8}, buf.getvalue())
+        write(io, data)
+        plt.close(fig)
         return true
     catch exc
         if exc isa PyException
@@ -113,5 +120,5 @@ end
 function init_pyshow()
     pyshow_add_rule(pyshow_rule_mimebundle)
     pyshow_add_rule(pyshow_rule_repr)
-    # pyshow_add_rule(pyshow_rule_savefig)
+    pyshow_add_rule(pyshow_rule_savefig)
 end

src/compat/multimedia.jl

@@ -2,7 +2,6 @@ Base.@kwdef mutable struct Config
     meta :: String = ""
     auto_sys_last_traceback :: Bool = true
     auto_fix_qt_plugin_path :: Bool = true
-    auto_pyplot_show :: Bool = true
     auto_ipython_display :: Bool = true
 end