Analyzing precipitation and sunshine duration

The KNMI De Bilt data file has a column containing precipitation duration values in 0.1 hours. The sunshine duration also given in 0.1 hours is derived from global radiation values. Notice the use of the word global and not solar. Hence, there are other sources of radiation taken into account here, but details are not very important right now. We will plot a histogram of precipitation duration values. However, we will omit the days when no rain fell, because there are so many dry days that it skews the overall picture. We will also display the monthly average precipitation and sunshine durations. The following steps describe the rainfall and sunlight length study:

1. We will load the dates converted into months, sunshine, and precipitation duration into NumPy arrays. Again, we convert missing values to NaN. The code is as follows:

   to_float = lambda x: float(x.strip() or np.nan)
   to_month = lambda x: dt.strptime(x, "%Y%m%d").month
   months, sun_hours...