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Fix image fmt detection for Path input. #10754

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Merged
jklymak merged 1 commit into from
Mar 12, 2018
Merged

Fix image fmt detection for Path input. #10754

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2 changes: 2 additions & 0 deletions lib/matplotlib/backend_bases.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2130,6 +2130,8 @@ def print_figure(self, filename, dpi=None, facecolor=None, edgecolor=None,

if format is None:
# get format from filename, or from backend's default filetype
if isinstance(filename, getattr(os, "PathLike", ())):

@timhoffm timhoffm Mar 12, 2018

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Am I correct, that this will only fix the format detection for Python 3.6+? Since this will probably go into 2.2.x. it should also hande pre-python3.6 Path objects, i.e. check for Path instance and use filename = str(filename)?

@timhoffm timhoffm Mar 12, 2018

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Also PEP-519 states

Libraries wishing to support path objects and a version of Python prior to Python 3.6 and the existence of os.fspath() can use the idiom of path.__fspath__() if hasattr(path, "__fspath__") else path.

But that's more a matter of taste.

@anntzer anntzer Mar 12, 2018

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The original PR explicitly only supported 3.6+ (see whatsnew note in https://github.com/matplotlib/matplotlib/pull/10231/files). I have no intent to reimplement the pathlike API on <3.6.

So I'll leave things as they are.

filename = os.fspath(filename)
if isinstance(filename, six.string_types):
format = os.path.splitext(filename)[1][1:]
if format is None or format == '':
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10 changes: 7 additions & 3 deletions lib/matplotlib/tests/test_figure.py
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Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
from __future__ import absolute_import, division, print_function

import os
import sys
import warnings

Expand Down Expand Up @@ -379,6 +378,11 @@ def test_figure_repr():

@pytest.mark.skipif(sys.version_info < (3, 6), reason="requires Python 3.6+")
@pytest.mark.parametrize("fmt", ["png", "pdf", "ps", "eps", "svg"])
def test_fspath(fmt):
def test_fspath(fmt, tmpdir):
from pathlib import Path
plt.savefig(Path(os.devnull), format=fmt)
out = Path(tmpdir, "test.{}".format(fmt))
plt.savefig(out)
with out.open("rb") as file:
# All the supported formats include the format name (case-insensitive)
# in the first 100 bytes.
assert fmt.encode("ascii") in file.read(100).lower()