Category: Python

def punctuate(sentence, phrase_type):
	if phrase_type == "exclamation":
		sentence_punct = sentence + "!"
	elif phrase_type == "question":
		sentence_punct = sentence + "?"
	elif phrase_type == "aside":
		sentence_punct = "(" + sentence + ".)"
	else:
		sentence_punct = sentence + "."
	return sentence_punct

def cylinder_surface_area(radius, height, has_top_and_bottom):
	side_area = height * 6.28 * radius
	if has_top_and_bottom:
		top_area = 3.14 * radius ** 2
		return top_area + side_area
	else:
		return side_area

errors = 3
if errors:
	print("There are " + errors + " mistakes. Please correct.")
else:
	print("No mistakes here!")

def convert_to_numeric(score):
    """
    Convert the score to a numerical type.
    """
    converted_score = float(score)
    return converted_score

def sum_of_middle_three(score1,score2,score3,score4,score5):
    """
    Find the sum of the middle three numbers out of the five given.
    """
    max_score = max(score1,score2,score3,score4,score5)
    min_score = min(score1,score2,score3,score4,score5)
    sum = score1 + score2 + score3 + score4 + score5 - max_score - min_score
    return sum

def score_to_rating_string(score):
    if score < 1:
    	return "Terrible"
    elif score < 2:
    	return "Bad"
    elif score < 3:
    	return "OK"
    elif score < 4:
    	return "Good"
    elif score <= 5:
    	return "Excellent"
    else:
    	return "nothing"

def scores_to_rating(score1,score2,score3,score4,score5):

    score1 = convert_to_numeric(score1)
    score2 = convert_to_numeric(score2)
    score3 = convert_to_numeric(score3)
    score4 = convert_to_numeric(score4)
    score5 = convert_to_numeric(score5)

    #STEP 2 and STEP 3 find the average of the middle three scores
    average_score =     
        sum_of_middle_three(score1,score2,score3,score4,score5)/3

    #STEP 4 turn average score into a rating
    rating = score_to_rating_string(average_score)

    return rating

point = 189
prize = "No prize"

if point <= 50:
    prize = "wooden rabbit"
elif 51 <= point <= 150:
    prize = "No prize"
elif 151 <= point <= 180:
    prize = "wafer-thin mint"
elif 181 <= point <= 200:
    prize = "penguin"
    
if prize == "No prize":
    print("oh dear, no prize this time")
else:
    print("Congratulations! You have won a " + prize + "!" ) 

keywords like and, or and not

if is_raining and is_sunny:
	print("Is there a rainbow?")

if (not do_not_emai) and (location == "USA" or location == "CAN"):
	send_email()

if 18.5 <= weight_in_kg / (height_in_m)**2 < 25:
	print("BMI is considered 'normal'.")
&#91;/python&#93;

&#91;python&#93;
if numer % 2 == 0:
	print("The number " + str(number) + " is even.")
else:
	print("The number " + str(number) + " is odd.")
&#91;/python&#93;

&#91;python&#93;
def garden_calendar(season):
	if season == "spring":
		print("time to plant the garden!")
	elif season == "summer":
		print("time to water the garden!")
	elif season == "autumn" or season == "fall":
		print("time to harvest the garden!")
	elif season == "winter":
		print("time to stay indoors and drink tea!")
	elif:
		print("I don't recognize that season")
&#91;/python&#93;

&#91;python&#93;
phone_balance = 7.62
bank_balance = 104.39

if phone_balance < 10:
	phone_balance += 10
	bank_balance -= 10
print(phone_balance)
print(bank_balance)

number = 145346334
if number % 2 == 0:
	print("The number " + str(number) + " is even.")
else:
	print("The number " + str(number) + " is odd.")

age = 35

free_up_to_age = 4
child_up_to_age = 18
senior_from_age = 65

concession_ticket = 1.25
adult_ticket = 2.50

if age <= free_up_to_age:
	ticket_price = 0
elif age <= child_up_to_age:
	ticket_price = concession_ticket
elif age >= senior_from_age:
	ticket_price = concession_ticket
else:
	ticket_price = adult_ticket

message = "somebody who is {} years old will pay ${} to ride the bus.".format(age,ticket_price)
print(message)

>>> def cylinder_volume(height, radius):
	pi = 3.14159
	return height * pi * radius ** 2

>>> cylinder_volume(10, 3)
282.7431

def population_density(population, land_area):
    return population / land_area

test1 = population_density(10, 1)
expected_result1 = 10
print("expected result: {}, actual result: {}".format(expected_result1, test1))

test2 = population_density(864816, 121.4)
expected_result2 = 7123.6902801
print("expected result: {}..., actual result: {}".format(expected_result2, test2))

def readable_timedelta(days):
    week = days / 7
    day = days % 7
    return "{} week(s) and {} day(s)".format(week, day)
    
print(readable_timedelta(120))

>>> print(type(633))

>>> print(type("633"))

>>> print(type(633.0))

mon_sales = 121
tues_sales = 105
wed_sales = 110
thurs_sales = 98
fri_sales = 95
total = str(mon_sales + tues_sales + wed_sales + thurs_sales + fri_sales)
print("This week\'s total sales: " + total)

python string method
https://docs.python.org/3/library/stdtypes.html#string-methods

prophecy = "And there shall in that time be rumours of things going astray, and there will be a great confusion as to where things really are, and nobody will really know where lieth those little things with the sort of raffia work base, that has an attachment…at this time, a friend shall lose his friends’s hammer and the young shall not know where lieth the things possessed by their fathers that their fathers put there only just the night before around eight o’clock…"

vowel_count = 0
vowel_count += prophecy.count('a')
vowel_count += prophecy.count('A')
vowel_count += prophecy.count('e')
vowel_count += prophecy.count('E')
vowel_count += prophecy.count('i')
vowel_count += prophecy.count('I')
vowel_count += prophecy.count('o')
vowel_count += prophecy.count('O')
vowel_count += prophecy.count('u')
vowel_count += prophecy.count('U')

print(vowel_count)

format

log_message = "IP address {} accessed {} at {}".format(user_ip, url, now)

city = "Seoul"
high_temperature = 18
low_temperature = 9
temperature_unit = "degrees Celsius"
weather_conditions = "light rain"

alert = "Today's forecast for {}: The temperature will range from {} to {}{}. Conditions will be {}.".format(city, high_temperature, low_temperature, temperature_unit, weather_conditions)
# print the alert
print(alert)

>>> manila_pop = 1780148
>>> manila_area = 16.56
>>> manila_pop_density = manila_pop/manila_area
>>> print(int(manila_pop_density))
107496

bool

>>> 1 < 2
True
>>> 42 > 43
False

sf_population, sf_area = 864816, 231.89
rio_population, rio_area = 6453682, 486.5

san_francisco_pop_density = sf_population/sf_area
rio_de_janeiro_pop_density = rio_population/rio_area

print(san_francisco_pop_density > rio_de_janeiro_pop_density)

string

>>> print("hello")
hello
>>> print('hello')
hello
>>> welcome_message = "Hello, welcome to Tokyo"
>>> print(welcome_message)
Hello, welcome to Tokyo
>>> instructor_1 = "Philip"
>>> instructor_2 = "Charlie"
>>> print(instructor_1 + " and " + instructor_2)
Philip and Charlie

messiah = 'He\'s not the Messiah, he\'s a very naughty boy!'
print(messiah)

username = "Kinari"
timestamp = "04:50"
url = "http://petshop.com/pets/mammals/cats"
print(username + " accessed the site " + url + " at " + timestamp)

len

>>> tokyo_length = len("Tokyo")

>>> print(tokyo_length)

5

given_name = "Charlotte"

middle_names = "Hippopotamus"

family_name = "Turner"
name_length = len(given_name+middle_names+family_name)
driving_licence_character_limit = 28

print(name_length <= driving_licence_character_limit)
[/python]

	

Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 27 2016, 15:19:22) [MSC v.1500 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> print(3+1)
4
>>> 3 + 1
4
>>> print(1 + 2 + 3 * 3)
12
>>> print((1 + 2 + 3) * 3)
18
>>> print(3**2)
9
>>> print(9 % 2)
1
>>> print(15 // 4)
3
>>> print(16 // 4)
4
>>> print(-5 // 4)
-2
>>> print((23 + 32 + 64)/ 3)
39

integer and floats

>>> print(3/4)
0
>>> print(16/4)
4
>>> 3 + 2.5
5.5
>>> 213.13
213.13
>>> 341.
341.0
>>> int(49.7)
49
>>> int(16/4)
4
>>> float(3520+3239)
6759.0
>>> print(0.1)
0.1
>>> print(0.1 + 0.1 + 0.1)
0.3

float e.g.
Length of a fish you caught, in metres
Length of time it took to catch the first fish, in hours

4.445e8 is equal to 4.445 * 10 ** 8 which is equal to 444500000.0.

# The current volume of a water reservoir (in cubic metres)
reservoir_volume = 4.445e8
# The amount of rainfall from a storm (in cubic metres)
rainfall = 5e6

# decrease the rainfall variable by 10% to account for runoff
rainfall *= 0.9
# add the rainfall variable to the reservoir_volume variable
reservoir_volume += rainfall
# increase reservoir_volume by 5% to account for stormwater that flows
reservoir_volume *= 1.05 
# into the reservoir in the days following the storm

# decrease reservoir_volume by 5% to account for evaporation
reservoir_volume *= 0.95
# subtract 2.5e5 cubic metres from reservoir_volume to account for water
# that's piped to arid regions.
reservoir_volume -= 2.5e5
# print the new value of the reservoir_volume variable
print(reservoir_volume)

Two types of friction
static: moves when F > μs・N
kinetic: F = μk * N

wheel slip
rolling, rocked

speed = 120 km/h
μ=1.0: 3.4s
μ=0.7: 4.9s

F = m*a
u*gravitational force(mg)
a = μ*g

t/ 120km/h = 1 / μg
t = 120km/h / μ*g

Computing the coefficient of Friction
s = 1 – w/v
F(s) = μ(s)*mqcG
V= -F(s)/mqc
F = ma
w = F(s)/mew – B

import math
from **** import *

h = 0.01
mass_quarter_car = 250.
mass_effective_wheel = 20.
g = 9.81

end_time = 5.
num_steps = int(end_time / h)

w = numpy.zeros(num_steps + 1)
v = numpy.zeros(num_steps + 1)
x = numpy.zeros(num_steps + 1)
times = h * numpy.array(range(num_steps + 1))

@show_plot(7, 7)
def plot_me():
	axes_x = matplotlib.pyplot.subplot(411)
	axes_v = matplotlib.pyplot.subplot(412)
	axes_w = matplotlib.pyplot.subplot(413)
	awes_s = matplotlib.pyplot.subplot(414)

	def friction_coeff(slip):
		return 1.1 * (1. - math.exp(-20. * slip)) - 0.4 * slip

	def wheel_slip():
		b_values = numpy.arange(70., 190.1, 30.)
		for b in b_values:
			x[0] = 0.

			for step in range(num_steps):
				if v[step] < 0.01:
					break
				s = max(0., 1. - w[step] / v[step])

				w[step + 1] = max(0., w[step + 1])

			axes_x.plot(times[:step], x[:step])
			axes_v.plot(times[:step], v[:step])
			axes_w.plot(times[:step], w[:step])
			axes_s.plot(times[:step], 1. - w[:step] / v[:step])
			p = int((0.35 + 0.4 * (b - b_values[0])/ (b_values[-1] - b_values[0])) * num_steps)
			axes_x.annotate(b, (times[p], x[p]),
					xytext = (-30, -30), textcoords = 'offset point',
					arrowprops = dict(arrowstyle = '-', connectionstyle = 'arc3, '))

			p = int((0.35 + 0.4 * (v - b_values[0]) / (b_values[-1] - b_values[0])) * num_steps)
			axes_x.annotate(b, (times[p], x[p]),
				xytext = (-30, -30), textcoords - 'offset points',
				arrowprops = dict(arrowstyle = '-', connectionstyle = 'arc3, rad = 0.2', shrinkB = 0.))

		return x, v, w

    axes_x.set_ylabel('Position\nin m', multialignment = 'center')
    axes_v.set_ylabel('Car velocity\nin m/s', multialignment = 'center')
    axes_w.set_ylabel('Wheel velocity\nin m/s', multialignment = 'center')
    axes_s.set_ylabel('Wheel\nslip', multialignment = 'center')
    axes_s.set_xlabel('Time in s')
    axes_s.set_ylim(0., 1.)

    return wheel_slip()

x, v, w = plot_me()

x(t) = (x(t)^2 + 1)/2
with * (0) = 3

from *** import *

end_time = 42.
h = 0.0001
num_steps = int(end_time / h)
times = h * numpy.array(range(num_steps) + 1)

x = numpy.zeros(num_steps + 1)
x[0] = 3.

def forward_euler():
	for step in range(num_steps):

	return x

x = forward_euler()

@show_plot
def plot_me():
	matplotlib.pyplot.plot(times, x)
	matplotlib.pyplot.show()

plot_me()

Sources of Errors
-model, parameters, initial data, numerics

Exp growth, Amount of fish

from xxx import *

harvest_rates = [2e4, 5e4, 1e5, 2e5]

data = []

def logistic_growth():
	maximum_growth_rate = 0.5
	carrying_capacity = 2e6

	end_time = 10.
	h = 0.1
	num_steps = in(end_time / h)
	times = h * numpy.array(range(num_steps + 1))

	fish = numpy.zeros(num_steps + 1)
	fish[0] = 2e5

	for harvest_rate in harvest_rates:

		data.append(([time for time in times], [f for f in fish],
			str(harvest_rate)))

	return fish

fish = logistic_growth()

@show_plot
def plot_me():
    fish_plots = []
    for (times, fish, rate_label) in data:
        fish_plots.append(matplotlib.pyplot.plot(times, fish, label=rate_label))    
    matplotlib.pyplot.legend([str(rate) for rate in harvest_rates], loc='upper right')
    axes = matplotlib.pyplot.gca()
    axes.set_xlabel('Time in years')
    axes.set_ylabel('Amount of fish in tons')

plot_me()