heatindexcomp.py

# Column names and column indices to read
columns = {'date': 0, 'time': 1, 'tempout': 2, 'humout': 5,
           'heatindex': 13}

# Data types for each column (only if non-string)
types = {'tempout': float, 'humout': float, 'heatindex': float}

# Initialize my data variable
data = {}
for column in columns:
   data[column] = []

# Read and parse the data file
filename = "data/wxobs20170821.txt"
with open(filename, 'r') as datafile:

   # Read the first three lines (header)
   for _ in range(3):
      datafile.readline()

   # Read and parse the rest of the file
   for line in datafile:
      split_line = line.split()
      for column in columns:
         i = columns[column]
         t = types.get(column, str)
         value = t(split_line[i])
         data[column].append(value)

   
# Compute the heat indx
def compute_heatindex(t, rh_pct):
   a = -42.379
   b = 2.04901523
   c = 10.14333127
   d = -0.22475541
   e = -0.00683783
   f = -0.05481717
   g = 0.00122874
   h = 0.00085282
   i = -0.00000199

   rh = rh_pct / 100

   hi = a + (b * t) + (c * rh) + (d * t * rh) \
      + (e * t**2) + (f * rh**2) + (g * t**2 * rh) \
      + (h * t * rh**2) + (i * t**2 * rh**2)
   return hi 
   
     
# Compute the wind chill factor
heatindex = []
for temp, hum in zip(data['tempout'], data['humout']):
   heatindex.append(compute_heatindex(temp, hum))
  
# Output comparison of data 
# f'' strings are a special symbol to allow you to format your string output
#   .5f means 5 digits to the right of the decimal point
#   can actually compute values within the curly brackets (in this case, the difference)
print('                   ORIGINAL     ESTIMATED              ')
print('  DATE    TIME     HEATINDEX    HEATINDEX    DIFFERENCE')
print('------   -----     ---------    ---------    ----------')
zip_data = zip(data['date'],data['time'],data['heatindex'],heatindex)
for date, time, hi_data, hi_comp in zip_data:
    hi_diff = hi_data - hi_comp
    print(f'{date}   {time:>6}   {hi_data:9.6f}    {hi_comp:9.6f}    {hi_diff:10.6f}')