PERF: periodarr_to_dt64arr

asv_bench/benchmarks/tslibs/period.py

@@ -2,10 +2,15 @@
 Period benchmarks that rely only on tslibs.  See benchmarks.period for
 Period benchmarks that rely on other parts fo pandas.
 """
-from pandas import Period
+
+import numpy as np
+
+from pandas._libs.tslibs.period import Period, periodarr_to_dt64arr
 
 from pandas.tseries.frequencies import to_offset
 
+from .tslib import _sizes
+
 
 class PeriodProperties:
 
@@ -68,3 +73,34 @@ def setup(self, freq, is_offset):
 
     def time_period_constructor(self, freq, is_offset):
         Period("2012-06-01", freq=freq)
+
+
+class TimePeriodArrToDT64Arr:
+    params = [
+        _sizes,
+        [
+            1000,
+            1011,  # Annual - November End
+            2000,
+            2011,  # Quarterly - November End
+            3000,
+            4000,
+            4006,  # Weekly - Saturday End
+            5000,
+            6000,
+            7000,
+            8000,
+            9000,
+            10000,
+            11000,
+            12000,
+        ],
+    ]
+    param_names = ["size", "freq"]
+
+    def setup(self, size, freq):
+        arr = np.arange(10, dtype="i8").repeat(size // 10)
+        self.i8values = arr
+
+    def time_periodarray_to_dt64arr(self, size, freq):
+        periodarr_to_dt64arr(self.i8values, freq)

pandas/_libs/tslibs/period.pyx

@@ -56,6 +56,7 @@ from pandas._libs.tslibs.ccalendar cimport (
     get_days_in_month,
 )
 from pandas._libs.tslibs.ccalendar cimport c_MONTH_NUMBERS
+from pandas._libs.tslibs.conversion import ensure_datetime64ns
 
 from pandas._libs.tslibs.dtypes cimport (
     PeriodDtypeBase,
@@ -937,7 +938,7 @@ cdef inline int month_to_quarter(int month) nogil:
 
 @cython.wraparound(False)
 @cython.boundscheck(False)
-def periodarr_to_dt64arr(const int64_t[:] periodarr, int freq):
+def periodarr_to_dt64arr(periodarr: ndarray, freq: int) -> ndarray:
     """
     Convert array to datetime64 values from a set of ordinals corresponding to
     periods per period convention.
@@ -946,9 +947,26 @@ def periodarr_to_dt64arr(const int64_t[:] periodarr, int freq):
         int64_t[:] out
         Py_ssize_t i, l
 
-    l = len(periodarr)
+    if freq >= FR_DAY:
+        if freq == FR_NS:
+            return periodarr
+
+        if freq == FR_US:
+            dta = periodarr.view("M8[us]")
+        elif freq == FR_MS:
+            dta = periodarr.view("M8[ms]")
+        elif freq == FR_SEC:
+            dta = periodarr.view("M8[s]")
+        elif freq == FR_MIN:
+            dta = periodarr.view("M8[m]")
+        elif freq == FR_HR:
+            dta = periodarr.view("M8[h]")
+        elif freq == FR_DAY:
+            dta = periodarr.view("M8[D]")
+        return ensure_datetime64ns(dta)
 
-    out = np.empty(l, dtype='i8')
+    l = len(periodarr)
+    out = np.empty(l, dtype="i8")
 
     for i in range(l):
         out[i] = period_ordinal_to_dt64(periodarr[i], freq)