Premedicant Dose

"""The Premedicant Dose for animal type is the weight of animal multipled by drug dose_rate, divided by drug concertration."""
 
class Premedicant_dose(object):
    drug_concerntrations = {"metacam" : 5, "synulox" : 32.5, "ketamine" : 100} 
    rates = {
        'dog' : {"metacam" : 0.2, "synulox" : 12.5, "ketamine" : 2},
        'cat' : {"metacam" : 0.2, "synulox" : 12.5, "ketamine" : 5},
        'rabbit' : {"metacam" : 0.6, "synulox" : "contraindicated", "ketamine" : 20}
    }
 
    def __init__(self, species, weight, drug):
        self.species = species.lower()
        self.weight = float(weight)
        self.drug = drug.lower()
    
    def result(self):   
        if self.rates[self.species][self.drug] == "contraindicated":
            return "WARNING: %s is contraindicated in %ss" % (self.drug, self.species)
        elif self.rates[self.species][self.drug] > 0:
            return (self.weight * self.rates[self.species][self.drug]) / self.drug_concerntrations[self.drug]
        else:
            return "Sorry, I'm a stupid computer. Please try again."


"""There are three raw_inputs (speciesQ, weightQ, drugQ) which each have defensive programming to ensure the user input is correct."""

# Loop 1. 
# the following while loop is the speciesQ input and defensive programming. Results should be dog, cat, or rabbit.
# strip() removes the whitespace and saves lowercase into speciesQ_stripped.

while True: 
    speciesQ = raw_input("Enter the species as dog, cat, or rabbit: ")
    speciesQ_stripped = speciesQ.lower().strip()
    if speciesQ_stripped == "dog" or speciesQ_stripped == "cat" or speciesQ_stripped == "rabbit":
        break

# Loop 2.
# the following while loop follows a solution found at http://stackoverflow.com/questions/4138202/python-using-isdigit-for-floats.
# the solution aimed to test for a float and the a number greater than zero and less thank a weight range for each animal.

import re       # regular expressions
p = re.compile('\d+(\.\d+)?')       # no idea what or how this works
weight_range = {"dog" : 100.0, "cat" : 15.0, "rabbit" : 15.0}

while True:
    weightQ = raw_input("Enter the weight (kg) of the animal: ")
    if (p.match(weightQ) != None) and (float(weightQ) > 0) and (float(weightQ) < weight_range[speciesQ_stripped]):
        break    

# Loop 3.
# the following while loop is similar to the above while loop for speciesQ.

while True:
    drugQ = raw_input("Enter the drug type as metacam, synulox, or ketamine: ")
    drugQ_stripped = drugQ.lower().lower().strip()
    if  drugQ_stripped == "metacam" or drugQ_stripped == "synulox" or drugQ_stripped == "ketamine":
        break


# Call to the class at the top (Premedicant_dose) utilising the stripped/lowercase version of the user raw_input (the class won't work otherwise)
 
user_input = Premedicant_dose(speciesQ_stripped, weightQ, drugQ_stripped)    #note: stripped
 
print #blank line
print "Results for premedicant dose of %s for a %s that weighs %s kg: " % (drugQ_stripped, speciesQ_stripped, str(weightQ))    #note: stripped
print #blank line
print str(round(user_input.result())) + "ml"    # note: rounded string, prints eg 12.34ml