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PdfPages: add option to delete empty file when closed #2453

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Merged
merged 3 commits into from
Sep 30, 2013
Merged

PdfPages: add option to delete empty file when closed #2453

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5f60446
add option to delete empty PdfPages when closed
megies Sep 23, 2013
dffaf4e
clearer comments in test
megies Sep 24, 2013
cb805ad
refactor docstrings of PdfPages
megies Sep 24, 2013
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70 changes: 48 additions & 22 deletions lib/matplotlib/backends/backend_pdf.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2249,29 +2249,44 @@ class PdfPages(object):
"""
A multi-page PDF file.

Use like this::

# Initialize:
with PdfPages('foo.pdf') as pdf:

# As many times as you like, create a figure fig and save it:
# When no figure is specified the current figure is saved
pdf.savefig(fig)
pdf.savefig()

(In reality PdfPages is a thin wrapper around PdfFile, in order to
avoid confusion when using savefig and forgetting the format
argument.)
Examples
--------

>>> import matplotlib.pyplot as plt
>>> # Initialize:
>>> with PdfPages('foo.pdf') as pdf:
... # As many times as you like, create a figure fig and save it:
... fig = plt.figure()
... pdf.savefig(fig)
... # When no figure is specified the current figure is saved
... pdf.savefig()

Notes
-----

In reality :class:`PdfPages` is a thin wrapper around :class:`PdfFile`, in
order to avoid confusion when using :func:`~matplotlib.pyplot.savefig` and
forgetting the format argument.
"""
__slots__ = ('_file',)
__slots__ = ('_file', 'keep_empty')

def __init__(self, filename):
def __init__(self, filename, keep_empty=True):
"""
Create a new PdfPages object that will be written to the file
named *filename*. The file is opened at once and any older
file with the same name is overwritten.
Create a new PdfPages object.

Parameters
----------

filename: str
Plots using :meth:`PdfPages.savefig` will be written to a file at
this location. The file is opened at once and any older file with
the same name is overwritten.
keep_empty: bool, optional
If set to False, then empty pdf files will be deleted automatically
when closed.
"""
self._file = PdfFile(filename)
self.keep_empty = keep_empty

def __enter__(self):
return self
Expand All @@ -2285,6 +2300,8 @@ def close(self):
PDF file.
"""
self._file.close()
if self.get_pagecount() == 0 and self.keep_empty is False:
os.remove(self._file.fh.name)
self._file = None

def infodict(self):
Expand All @@ -2297,10 +2314,19 @@ def infodict(self):

def savefig(self, figure=None, **kwargs):
"""
Save the Figure instance *figure* to this file as a new page.
If *figure* is a number, the figure instance is looked up by
number, and if *figure* is None, the active figure is saved.
Any other keyword arguments are passed to Figure.savefig.
Saves a :class:`~matplotlib.figure.Figure` to this file as a new page.

Any other keyword arguments are passed to
:meth:`~matplotlib.figure.Figure.savefig`.

Parameters
----------

figure: :class:`~matplotlib.figure.Figure` or int, optional
Specifies what figure is saved to file. If not specified, the
active figure is saved. If a :class:`~matplotlib.figure.Figure`
instance is provided, this figure is saved. If an int is specified,
the figure instance to save is looked up by number.
"""
if isinstance(figure, Figure):
figure.savefig(self, format='pdf', **kwargs)
Expand Down
36 changes: 36 additions & 0 deletions lib/matplotlib/tests/test_backend_pdf.py
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Original file line number Diff line number Diff line change
Expand Up @@ -50,3 +50,39 @@ def test_multipage_pagecount():
assert pdf.get_pagecount() == 1
pdf.savefig()
assert pdf.get_pagecount() == 2


@cleanup
def test_multipage_keep_empty():
from matplotlib.backends.backend_pdf import PdfPages
from tempfile import NamedTemporaryFile
### test empty pdf files
# test that an empty pdf is left behind with keep_empty=True (default)
with NamedTemporaryFile(delete=False) as tmp:
with PdfPages(tmp) as pdf:
filename = pdf._file.fh.name
assert os.path.exists(filename)
os.remove(filename)
# test if an empty pdf is deleting itself afterwards with keep_empty=False
with NamedTemporaryFile(delete=False) as tmp:
with PdfPages(tmp, keep_empty=False) as pdf:
filename = pdf._file.fh.name
assert not os.path.exists(filename)
### test pdf files with content, they should never be deleted
fig = plt.figure()
ax = fig.add_subplot(111)
ax.plot([1, 2, 3])
# test that a non-empty pdf is left behind with keep_empty=True (default)
with NamedTemporaryFile(delete=False) as tmp:
with PdfPages(tmp) as pdf:
filename = pdf._file.fh.name
pdf.savefig()
assert os.path.exists(filename)
os.remove(filename)
# test that a non-empty pdf is left behind with keep_empty=False
with NamedTemporaryFile(delete=False) as tmp:
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What does this last block add?

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the comment in line 75 covers both blocks actually, but you're right maybe, I can split it up for clarity.

with PdfPages(tmp, keep_empty=False) as pdf:
filename = pdf._file.fh.name
pdf.savefig()
assert os.path.exists(filename)
os.remove(filename)