A Soft Starter: Max Daylight¶

This notebook will show you the process of using a simple geocat-comp function.

Finding an old NCL function¶

Say you have an old NCL script that you are looking to convert into python that uses the daylight_fao56 routine and you want to see if GeoCAT has converted the function to python.

daylight_fao56 NCL documentation

The best way to find the python equivalent function, if it exists, is to go to GeoCAT-comp’s documentation and search for the function name, as shown below. If functions are a translation of NCL functions, they will have their NCL counterparts linked in the documentation.

We can see that the GeoCAT-comp equivalent of NCL’s daylight_fao56 is max_daylight, which we can now use in our python script to provide the same functionality as existed in NCL.

Imports¶

[1]:

from geocat.comp import max_daylight
import xarray as xr
import numpy as np

Now, let’s look at max_daylight’s documentation to see what it does.

Calculate maximum daylight hours¶

So, let’s get the number of daylight hours for an entire year in Boulder (lat approx 40N)

[2]:

daylight_hours = max_daylight(np.arange(0, 365), 40)

Now, let’s put our data into an xarray DataArray.

This could, of course, have all been done in one step, but we wanted to introduce the absolute basics of geocat-comp.

[3]:

daylight_hours = xr.DataArray(daylight_hours, dims=("days", "hours of daylight"))
daylight_hours

[3]:

<xarray.DataArray (days: 365, hours of daylight: 1)>
array([[ 9.21056836],
       [ 9.22130351],
       [ 9.23298075],
       [ 9.24559158],
       [ 9.25912689],
       [ 9.27357699],
       [ 9.2889316 ],
       [ 9.30517995],
       [ 9.32231074],
       [ 9.34031217],
       [ 9.35917201],
       [ 9.3788776 ],
       [ 9.39941587],
       [ 9.42077339],
       [ 9.44293638],
       [ 9.46589074],
       [ 9.4896221 ],
       [ 9.51411584],
       [ 9.53935709],
       [ 9.56533079],
...
       [ 9.20073221],
       [ 9.19190951],
       [ 9.1840506 ],
       [ 9.17716138],
       [ 9.171247  ],
       [ 9.16631194],
       [ 9.16235992],
       [ 9.15939395],
       [ 9.15741629],
       [ 9.15642843],
       [ 9.15643115],
       [ 9.15742443],
       [ 9.15940751],
       [ 9.16237889],
       [ 9.1663363 ],
       [ 9.17127674],
       [ 9.17719647],
       [ 9.18409103],
       [ 9.19195523],
       [ 9.20078319]])
Dimensions without coordinates: days, hours of daylight

A little visualization¶

And now, let’s take a little peek at the data using xarray’s built-in plotting functionality:

[4]:

daylight_hours.plot()

Matplotlib is building the font cache; this may take a moment.

[4]:

[<matplotlib.lines.Line2D at 0x7f9fb3426350>]

../../_images/notebooks_geocat-comp_01-using_geocat_comp_16_2.png

Introduction to GeoCAT-comp A More Complicated Example: Calculating Climatological Averages