now sectionwise: date_converter: delta / time

pandas/io/date_converters.py

@@ -1,4 +1,6 @@
 """This module is designed for community supported date conversion functions"""
+from datetime import datetime, timedelta, time
+
 from pandas.compat import range
 import numpy as np
 import pandas.lib as lib
@@ -56,3 +58,76 @@ def _check_columns(cols):
             raise AssertionError()
 
     return N
+
+
+## Datetime Conversion for date_parsers
+## see also: create a community supported set of typical converters
+##           https://github.com/pydata/pandas/issues/1180
+
+def offset_datetime(dt_in, days=0, hours=0, minutes=0,
+                    seconds=0, microseconds=0):
+    '''appply corrective time offset using datetime.timedelta
+
+    input
+    -----
+    dt_in : datetime.time or datetime.datetime object
+    days : integer value (positive or negative) for days component of offset
+    hours : integer value (positive or negative) for hours component of offset
+    minutes : integer value (positive or negative) for
+              minutes component of offset
+    seconds : integer value (positive or negative) for
+              seconds component of offset
+    microseconds : integer value (positive or negative) for
+                   microseconds component of offset
+
+    output
+    ------
+    ti_corr : datetime.time or datetime.datetime object
+
+
+    '''
+    # if a excel time like '23.07.2013 24:00' they actually mean
+    # in Python '23.07.2013 23:59', must be converted
+#            offset = -10 # minutes
+    delta = timedelta(days=days, hours=hours, minutes=minutes,
+                      seconds=seconds, microseconds=microseconds)
+
+    #check if offset it to me applied on datetime or time
+    if type(dt_in) is time:
+        #create psydo datetime
+        dt_now = datetime.now()
+        dt_base = datetime.combine(dt_now, dt_in)
+    else:
+        dt_base = dt_in
+
+    dt_corr = (dt_base) + delta
+
+    #if input is time, we return it.
+    if type(dt_in) is time:
+        dt_corr = dt_corr.time()
+
+    return dt_corr
+
+
+def dt2ti(dt_in):
+    '''converts wrong datetime.datetime to datetime.time
+
+    input
+    -----
+    dt_in : dt_in : datetime.time or datetime.datetime object
+
+    output
+    -------
+    ti_corr : datetime.time object
+    '''
+    # so we correct those which are not of type :mod:datetime.time
+    # impdt2tiortant hint:
+    # http://stackoverflow.com/a/12906456
+    if type(dt_in) is not time:
+        dt_in = dt_in.time()
+    elif type(dt_in) is datetime:
+        dt_in = dt_in.time()
+    else:
+        pass
+
+    return dt_in

pandas/io/tests/test_date_converters.py

@@ -1,5 +1,5 @@
 from pandas.compat import StringIO, BytesIO
-from datetime import date, datetime
+from datetime import datetime, time, timedelta, date
 import csv
 import os
 import sys
@@ -120,6 +120,34 @@ def test_generic(self):
         self.assert_('ym' in df)
         self.assert_(df.ym.ix[0] == date(2001, 1, 1))
 
+    def test_offset_datetime(self):
+        #test with a datetime.datetime object
+        dt_in = datetime(2013, 1, 1, 1, 10, 10, 100000)
+        dt_target = datetime(2013, 1, 2, 6, 20, 40, 100600)
+        dt_res = conv.offset_datetime(dt_in, days=1, hours=5, minutes=10,
+                                      seconds=30, microseconds=600)
+
+        assert(dt_res == dt_target)
+        #test with a datetime.time object
+        ti_in = time(1, 10, 20, 100000)
+        ti_target = time(6, 20, 50, 100600)
+        ti_res = conv.offset_datetime(ti_in, hours=5, minutes=10,
+                                      seconds=30, microseconds=600)
+        assert(ti_res == ti_target)
+
+    def test_dt2ti(self):
+        #a datetime.datetime object
+        dt_in = datetime(2013, 1, 1, 1, 10, 10, 100000)
+        ti_target = time(1, 10, 10, 100000)
+        dt2ti_dt_res = conv.dt2ti(dt_in)
+        assert(ti_target == dt2ti_dt_res)
+
+        #a datetime.time object
+        ti_in = time(1, 10, 20, 100000)
+        ti_target_dt2ti = time(1, 10, 20, 100000)
+        dt2ti_ti_res = conv.dt2ti(ti_in)
+        assert(ti_target_dt2ti == dt2ti_ti_res)
+
 
 if __name__ == '__main__':
     import nose