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-rw-r--r--numpy/lib/format.py22
1 files changed, 18 insertions, 4 deletions
diff --git a/numpy/lib/format.py b/numpy/lib/format.py
index 54fd0b0bc..8f3fd694d 100644
--- a/numpy/lib/format.py
+++ b/numpy/lib/format.py
@@ -623,13 +623,27 @@ def _read_array_header(fp, version, max_header_size=_MAX_HEADER_SIZE):
# "descr" : dtype.descr
# Versions (2, 0) and (1, 0) could have been created by a Python 2
# implementation before header filtering was implemented.
- if version <= (2, 0):
- header = _filter_header(header)
+ #
+ # For performance reasons, we try without _filter_header first though
try:
d = safe_eval(header)
except SyntaxError as e:
- msg = "Cannot parse header: {!r}"
- raise ValueError(msg.format(header)) from e
+ if version <= (2, 0):
+ header = _filter_header(header)
+ try:
+ d = safe_eval(header)
+ except SyntaxError as e2:
+ msg = "Cannot parse header: {!r}"
+ raise ValueError(msg.format(header)) from e2
+ else:
+ warnings.warn(
+ "Reading `.npy` or `.npz` file required additional "
+ "header parsing as it was created on Python 2. Save the "
+ "file again to speed up loading and avoid this warning.",
+ UserWarning, stacklevel=4)
+ else:
+ msg = "Cannot parse header: {!r}"
+ raise ValueError(msg.format(header)) from e
if not isinstance(d, dict):
msg = "Header is not a dictionary: {!r}"
raise ValueError(msg.format(d))