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PERF: write basic datetimes faster #10271

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merged 1 commit into from
Jun 4, 2015
Merged

PERF: write basic datetimes faster #10271

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1 change: 1 addition & 0 deletions doc/source/whatsnew/v0.16.2.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@ Performance Improvements
~~~~~~~~~~~~~~~~~~~~~~~~

- Improved ``Series.resample`` performance with dtype=datetime64[ns] (:issue:`7754`)
- Modest improvement in datetime writing speed in to_csv (:issue:`10271`)

.. _whatsnew_0162.bug_fixes:

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47 changes: 36 additions & 11 deletions pandas/tslib.pyx
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Expand Up @@ -5,20 +5,22 @@ from numpy cimport (int8_t, int32_t, int64_t, import_array, ndarray,
NPY_INT64, NPY_DATETIME, NPY_TIMEDELTA)
import numpy as np

from cpython.ref cimport PyObject
from cpython cimport (
PyTypeObject,
PyFloat_Check,
PyLong_Check,
PyObject_RichCompareBool,
PyObject_RichCompare,
PyString_Check,
Py_GT, Py_GE, Py_EQ, Py_NE, Py_LT, Py_LE
Py_GT, Py_GE, Py_EQ, Py_NE, Py_LT, Py_LE,
)

# Cython < 0.17 doesn't have this in cpython
cdef extern from "Python.h":
cdef PyTypeObject *Py_TYPE(object)
int PySlice_Check(object)
object PyUnicode_FromFormat(const char*, ...)

cdef extern from "datetime_helper.h":
double total_seconds(object)
Expand Down Expand Up @@ -1450,20 +1452,43 @@ def format_array_from_datetime(ndarray[int64_t] values, object tz=None, object f
elif basic_format:

pandas_datetime_to_datetimestruct(val, PANDAS_FR_ns, &dts)
res = '%d-%.2d-%.2d %.2d:%.2d:%.2d' % (dts.year,
dts.month,
dts.day,
dts.hour,
dts.min,
dts.sec)

if show_ns:
ns = dts.ps / 1000
res += '.%.9d' % (ns + 1000 * dts.us)
res = PyUnicode_FromFormat('%d-%02d-%02d %02d:%02d:%02d.%09d',
dts.year,
dts.month,
dts.day,
dts.hour,
dts.min,
dts.sec,
ns + 1000 * dts.us)
elif show_us:
res += '.%.6d' % dts.us
res = PyUnicode_FromFormat('%d-%02d-%02d %02d:%02d:%02d.%06d',
dts.year,
dts.month,
dts.day,
dts.hour,
dts.min,
dts.sec,
dts.us)

elif show_ms:
res += '.%.3d' % (dts.us/1000)
res = PyUnicode_FromFormat('%d-%02d-%02d %02d:%02d:%02d.%03d',
dts.year,
dts.month,
dts.day,
dts.hour,
dts.min,
dts.sec,
dts.us/1000)
else:
res = PyUnicode_FromFormat('%d-%02d-%02d %02d:%02d:%02d',
dts.year,
dts.month,
dts.day,
dts.hour,
dts.min,
dts.sec)

result[i] = res

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