I need to convert dates from pandas frame values in the separate function:
def myfunc(lat, lon, when):
ts = (when - np.datetime64('1970-01-01T00:00:00Z','s')) / np.timedelta64(1, 's')
date = datetime.datetime.utcfromtimestamp(ts)
print("Numpy date= ", when, " Python date= ", date)
return float(90) - next_func(lat, lon, date)
Invokation this function:
new_df['new_column'] = np.vectorize(my_func)(lat, lon, new_df['datetime(LT)'])
But it raise error:
ufunc subtract cannot use operands with types dtype('int64') and dtype('<M8[s]')
How to convert numpy datetime64 [ns] to python datetime?
I wonder if you need all this conversion work. With the right time units a datetime64
can produce a datetime
object directly.
I'm not sure about your when
variable, but let's assume it comes from pandas
, and is something like a DatetimeIndex
:
In [56]: time = pandas.date_range('6/28/2013', periods=5, freq='5D')
In [57]: time
Out[57]:
DatetimeIndex(['2013-06-28', '2013-07-03', '2013-07-08', '2013-07-13',
'2013-07-18'],
dtype='datetime64[ns]', freq='5D')
The equivalent numpy array
In [58]: time.values
Out[58]:
array(['2013-06-28T00:00:00.000000000', '2013-07-03T00:00:00.000000000',
'2013-07-08T00:00:00.000000000', '2013-07-13T00:00:00.000000000',
'2013-07-18T00:00:00.000000000'], dtype='datetime64[ns]')
In [59]: time.values.tolist()
Out[59]:
[1372377600000000000,
1372809600000000000,
1373241600000000000,
1373673600000000000,
1374105600000000000]
With [ns]
the result is a large integer, a 'timestamp' of some sort. But if I convert the time units to something like seconds, or even microseconds (us):
In [60]: time.values.astype('datetime64[s]')
Out[60]:
array(['2013-06-28T00:00:00', '2013-07-03T00:00:00',
'2013-07-08T00:00:00', '2013-07-13T00:00:00',
'2013-07-18T00:00:00'], dtype='datetime64[s]')
In [61]: time.values.astype('datetime64[s]').tolist()
Out[61]:
[datetime.datetime(2013, 6, 28, 0, 0),
datetime.datetime(2013, 7, 3, 0, 0),
datetime.datetime(2013, 7, 8, 0, 0),
datetime.datetime(2013, 7, 13, 0, 0),
datetime.datetime(2013, 7, 18, 0, 0)]
the result is a list of datetime
objects.
I prefer this workaround because sometimes np.datetime64 has different resolution
def ___convert_to_datetime(d):
return datetime.strptime(np.datetime_as_string(d,unit='s'), '%Y-%m-%dT%H:%M:%S')
for timestamp
def ___convert_to_ts(d):
return datetime.strptime(np.datetime_as_string(d,unit='s'), '%Y-%m-%dT%H:%M:%S').timestamp()
for instance
import numpy as np
from datetime import datetime
def ___convert_to_datetime(d):
return datetime.strptime(np.datetime_as_string(d,unit='s'), '%Y-%m-%dT%H:%M:%S')
def ___convert_to_ts(d):
return datetime.strptime(np.datetime_as_string(d,unit='s'), '%Y-%m-%dT%H:%M:%S').timestamp()
print(___convert_to_datetime(np.datetime64('2005-02-25')))
my_ns_date = np.datetime64('2009') + np.timedelta64(20, 'ns')
print(my_ns_date)
print(___convert_to_datetime(my_ns_date))
output will be
2005-02-25 00:00:00
2009-01-01T00:00:00.000000020
2009-01-01 00:00:00
def myfunc(lat, lon, when):
ts = (when - np.datetime64('1970-01-01T00:00:00Z','s')) / np.timedelta64(1, 's')
date = datetime.utcfromtimestamp(ts)
print("Numpy date= ", when, " Python date= ", date)
return float(90) - next_func(lat, lon, date)
try this code
to convert numpy datetime64[ns] to python datetime you just try the following code segment
from datetime import datetime
datetime.utcfromtimestamp('your_time_stamp')
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.