def bigger(a,b):
if a > b:
return a
else:
return b
def biggest(a,b,c):
return bigger(a,bigger(b,c))
def median(a,b,c):
biggest_number=biggest(a,b,c)
if a==biggest_number:
median_number=bigger(b,c)
else:
if b==biggest_number:
median_number=bigger(a,c)
else:
median_number=bigger(a,b)
return median_number
print median(4,5,6)
#Print numbers n,n-1,n-2,...,1, Blastoff
def countdown(n):
while n >= 1:
print n
n=n-1
print 'Blastoff'
countdown(9)
#Find the last position of a target string in the search string. If there are no occurrences output is -1.
def find_last(s,t):
post=0
result=s.find(t,post)
if result == -1:
return -1
else:
while result != -1:
post=result+1
result=s.find(t,post)
return post-1
find_last('abc','a') # Output will be 0.
#Print the multiplication table
def print_multiplication_table(n):
p=1
while p<=n:
m=1
while m <=n:
result=m*p
print str(p) + '*' + str(m) + '=' + str(result)
m=m+1
p=p+1
print_multiplication_table(10)
#To create a list, use
my_list=['a','b','d']
print my_list[0] #This will print a
#To create a tuple, use
my_tuple=('x','y')
#An example of accessing a nested list
countries = [['China','Beijing',1350],
['India','Delhi',1210],
['Romania','Bucharest',21],
['United States','Washington',307]]
#Write code to print out the capital of India by accessing the array.
print countries[1][1]
# List operations
my_list=[1,2]
my_list.append(3)
my_list=my_list + [4,5]
len(my_list) # This results 5
#List operations using append method
p=[1,2]
q=[3,4]
p.append(q)
print p
[1, 2, [3, 4]]
#Using a FOR loop to print out number of days in each month
days_in_month=[31,28,31,30,31,30,31,31,30,31,30,31]
months=[1,2,3,4,5,6,7,8,9,10,11,12]
for i in months:
print days_in_month[i-1]
#Using a FOR loop to print the sum of the list
def sum_list(my_list):
sum=0
for e in my_list:
sum=sum+e
return sum
print sum_list([1,7,4,8,9])
#The following function takes a list of strings and returns a new list that contains capitalized strings.
def capitalize_all(t):
result = []
for s in t:
result.append(s.capitalize())
return result
#Several ways to delete elements in the list
#Define a procedure, measure_udacity, that takes its input a list of Strings,
#and outputs a number that is a count of the number of elements in the input
#list that start with the letter 'U' (uppercase).
#measure_udacity(['Dave','Sebastian','Katy']) => 0
#measure_udacity(['Umika','Umberto']) => 2
def measure_udacity(my_list):
count=0
for i in range(len(my_list)):
if my_list[i][0]=='U':
count=count+1
return count
print measure_udacity(['Dave','Sebastian','Katy'])
#Another way to do it
def measure_udacity(my_list):
count=0
for e in my_list:
if e[0]=='U':
count=count+1
return count
print measure_udacity(['Dave','Sebastian','Katy'])
#Define a procedure, find_element, that takes as its inputs a List and a value of any type, and
#outputs the index of the first element in the input list that matches the value.
#If there is no matching element, output -1.
#find_element([1,2,3],3) => 2
#find_element(['alpha','beta'],'gamma') => -1
def find_element(my_list, t):
index=0
for e in my_list:
if e == t:
return index
index=index + 1
return -1
print find_element([1,2,5,3,6,3],3)
print find_element(['alpha','beta'],'gamma')
#Another way to do it using the 'index' method and 'in' operator
def find_element(my_list,t):
if t not in my_list:
return -1
else:
return my_list.index(t)
print find_element([1,2,3],3)
print find_element(['alpha','beta'],'gamma')
If we need to return the index for the output, a WHILE loop is a good choice.
>>> p=(0,1,2) #p is a tuple
>>> print p
(0, 1, 2)
>>> q=[0,1,2] #q is a list
>>> print q
[0, 1, 2]
<List>.pop()
Mutates <List> by removing its last element. Outputs the value of that element. If there are no elements in <List>, [].pop() produces an error.
# After running the procedure proc1(p) the value of p is unchanged.
def proc1(p):
p=p+[1]
#Define a procedure, greatest, that takes as input a list of positive numbers, and
#returns the greatest number in that list. If the input list is empty, the output should be 0.
#greatest([4,23,1]) => 23
#greatest([]) => 0
def greatest(my_list):
max=0
if len(my_list)==0:
return 0
else:
for e in my_list:
if e >= max:
max=e
return max
References
Allen B. Downey, Think Python: How to Think Like a Computer Scientist, http://www.greenteapress.com/thinkpython/html/index.html
Udacity, CS101 Lecture Notes, February-April 2012
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