how to read date and time on ecmwf file

Question

I have global datasets in netcdf file. Time information on data file is:

<type 'netCDF4._netCDF4.Variable'>
int32 time(time)
    units: hours since 1900-01-01 00:00:0.0
    long_name: time
    calendar: gregorian
unlimited dimensions: time
current shape = (5875,)
filling off

when I extracted time from file, I got this array:

array([ 876600,  876624,  876648, ..., 1017528, 1017552, 1017576], dtype=int32) 

my question is how to convert this array into proper date format? [Note: This is a daily data sets and number in an array is corresponding to an hours from 1900-01-01]

Answer 1

You could:

from datetime import date, timedelta

hours = [ 876600,  876624,  876648, 1017528, 1017552, 1017576]
base = date(1900, 1, 1)
for hour in hours:
    base + timedelta(hours=hour)

2000-01-02
2000-01-03
2000-01-04
2016-01-30
2016-01-31
2016-02-01

Use datetime instead of date if you want hour etc info.

Or using a pd.DataFrame:

df = pd.DataFrame(hours, columns=['hours'])
df['date'] = df.hours.apply(lambda x: base + timedelta(hours=x))

     hours        date
0   876600  2000-01-02
1   876624  2000-01-03
2   876648  2000-01-04
3  1017528  2016-01-30
4  1017552  2016-01-31
5  1017576  2016-02-01