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PERF: Fixed decoding perf issue on py3 (GH5441) #5448

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Merged
merged 1 commit into from
Nov 6, 2013
Merged

PERF: Fixed decoding perf issue on py3 (GH5441) #5448

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1 change: 1 addition & 0 deletions doc/source/release.rst
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Expand Up @@ -531,6 +531,7 @@ Bug Fixes
names weren't strings (:issue:`4956`)
- A zero length series written in Fixed format not deserializing properly.
(:issue:`4708`)
- Fixed decoding perf issue on pyt3 (:issue:`5441`)
- Fixed bug in tslib.tz_convert(vals, tz1, tz2): it could raise IndexError
exception while trying to access trans[pos + 1] (:issue:`4496`)
- The ``by`` argument now works correctly with the ``layout`` argument
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7 changes: 5 additions & 2 deletions pandas/io/pytables.py
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Expand Up @@ -3972,8 +3972,11 @@ def _unconvert_string_array(data, nan_rep=None, encoding=None):
# where the passed encoding is actually None)
encoding = _ensure_encoding(encoding)
if encoding is not None and len(data):
f = np.vectorize(lambda x: x.decode(encoding), otypes=[np.object])
data = f(data)
try:
data = data.astype(str).astype(object)
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So this branch works when you only have ascii letters/numbers in your output? Otherwise always needs to be decoded, right?

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no it always works with an individual decoding, just slow. the astyping to str works when the input can be safely decoded by the astype(str) (which is prob just a UTF-8 decode on numpy side thats in c)

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Okay (I meant the astyping line) sounds good.

except:
f = np.vectorize(lambda x: x.decode(encoding), otypes=[np.object])
data = f(data)

if nan_rep is None:
nan_rep = 'nan'
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