I am trying to read some date info from Excel using openpyxl
which returns them as datetime.datetime
. I need to resample the data and then plot the resampled times using matplotlib
. I would like an array of dates starting at tmin
, incremented by 30.0 days.
The code stub is
import numpy as np
import datetime
vals = [
datetime.date.fromisoformat('2004-06-01'),
datetime.date.fromisoformat('2004-07-01'),
datetime.date.fromisoformat('2004-08-01'),
datetime.date.fromisoformat('2004-09-01'),
datetime.date.fromisoformat('2004-10-01'),
datetime.date.fromisoformat('2004-11-01')]
xtim = np.array(vals)
tmin = np.min(xtim)
ytim = np.arange(0.0, 150.0, 30.0)
tnew = tmin ytim.astype('timedelta64[D]')
Unfortunately, this gives me the error message
UFuncTypeError: ufunc 'add' cannot use operands with types dtype('O') and dtype('<m8[D]')
CodePudding user response:
You should wrap tmin
in an array with 'datetime64' type:
np.array(tmin, dtype='datetime64') ytim.astype('timedelta64[D]')
output: array(['2004-06-01', '2004-07-01', '2004-07-31', '2004-08-30', '2004-09-29'], dtype='datetime64[D]')
CodePudding user response:
To add 30 days I'd suggest using datetime.timedelta(days=30)
.
For example as:
import numpy as np
import datetime
vals = [
datetime.date.fromisoformat('2004-06-01'),
datetime.date.fromisoformat('2004-07-01'),
datetime.date.fromisoformat('2004-08-01'),
datetime.date.fromisoformat('2004-09-01'),
datetime.date.fromisoformat('2004-10-01'),
datetime.date.fromisoformat('2004-11-01')]
xtim = np.array(vals)
tmin = np.min(xtim)
t_new=[tmin datetime.timedelta(days=i) for i in np.arange(0.0, 150.0, 30.0)]