intro.py

from __future__ import print_function
import math
#1. Write a loop that prints out the numbers from 20 to 10

for i in range(20,9, -1):
    print(i)
   
# 2. Now with list comprehension
x = [print(i) for i in range(20,9,-1)]


#3. Write a loop that prints out only the numbers from 20 to 10 that are even

even_list = []
for i in range(20,9, -1):
    if i%2 == 0:
        even_list.append(i)
print(even_list)


#4. Write a list comprehension that prints out only the numbers from 20 to 10 that are even
x = [print(i) for i in range(20,9,-1) if i%2 == 0]

def is_prime(n):
    for i in range(3, n):
        if n % i == 0:
            return False
    return True
 
# Let us  test            
x = 199
if is_prime(x):
    print( x, "is prime")
else:
    print(x, "is not prime")
    
# 6. Write a function that loads a text file, loops over the lines in it, and prints out the
# fifth character on the fifth line of that file.
# Sorry - I know this is ugly
with open("test_text.txt") as data:
    line_counter = 1
    for line in data:
        if line_counter == 5:
            print(line[4])
        line_counter+=1
        
        
# Ok Wolf, you moron. You can do this as list comprehension
with open("test_text.txt") as data:
    x = [print(line[4])for line in data if line == 4]

# 7. Write a loop that prints out the numbers from 1 to 20, printing “Good: NUMBER” if the number is
# divisible by five and “Job: NUMBER” if then number is prime, and nothing otherwise.

def is_div_by_five(x):
    return True if x%5 == 0 else False

for i in range(1,20):
    if i == 5:
        print("good job ", i)
    elif is_div_by_five(i):
        print("good ", i)
    elif is_prime(i):
        print("job ", i)


# 8. A biologist is modelling population growth using a Gompertz curve, which is defined as y(t) = a.e−b.e−c.t
# where y is population size, t is time, a and b are parameters, and e is the exponential function. Write
# them a function that calculates population size at any time for any values of its parameters.

def gompertz(a, b, c, t):
    return(a * math.exp(-b * math.exp(-c * t)))

print(gompertz(2, 3, 4, 5))


#9. Write a function that draws boxes of a specified width and height that look like this (height 3, width 5):
#*****
#* *
#*****
#(Hint: what does print("*" + "" + "*"*4) give you?)

# NOte the funky numbers are to get it to look pretty with command line run

def make_box(height, width):
    print(width * "*") # top line
    for row in range(height - 2): # middle bit
        print("*", " " * (width-4), "*")
    print(width * "*") # bottom line
make_box(17,19)

# 10. Implement a point class that holds x and y information for a point in space. 
# Note that I am not asking you to plot that line.
# 11. Write a distance method that calculates the distance between two points in space.
# Note that I am not (yet) taking into account negative values

class points_in_space:
    def __init__(self, lat = 0, lon = 0):
        self.lat, self.lon  = lat, lon

class two_points:
    def __init__(self, a, b):
        self.a, self.b = a, b
    def dist(a, b):
        return math.sqrt(((a.lat - b.lat)**2)*(a.lon - b.lon)**2)     

point_a = points_in_space(6.0, 7.5) 
point_b = points_in_space(2.4, 16.3)
# The above seems to work nicely
# But cannot find a way to generate method WITH the class to work on TWO points
# Two solutions. One is to make an external function. Works perfectly.
# Or create another class called two-points

#def dist(a, b):
    #return math.sqrt(((a.lat - b.lat)**2)*(a.lon - b.lon)**2)
    
points_list = two_points(point_a, point_b)
print(points_list.dist)  


# 12. Implement a line class that takes two point objects and makes a line between them. 
# Note that I am not asking you to plot that line.   
class line_bet_points:
    def __inti__(self, point_a, point_b):
        return line