Looping Syntax

Loops are used for repetitive tasks:

Instead of this:

print("string")  print("string")  print("string")  print("string") …

You can do this:

x=1  while x<5:     print("string")

x=1
while x<5:
    print("string")
    print("Current x  is :",x)
    x=x+1
    print("Final x  is :",x)

string
Current x  is : 1
Final x  is : 2
string
Current x  is : 2
Final x  is : 3
string
Current x  is : 3
Final x  is : 4
string
Current x  is : 4
Final x  is : 5

Counted Loop

for x in range(1,5):     print (x)

for x in range(1,5):
    print(x)

1
2
3
4

# counted loop
n = range(1,10,5)
print(n)
for i in n:
    print (i, "python")

range(1, 10, 5)
1 python
6 python

List Loop

• Lost loops iterate over the value in a list

• The loop will execute once for each value in the list

# list loop
mylist = [[1,2],[3,6],[4,5]]
# number of columns in a multi dimensional list - len(mylist[0]) ->2
# number of rows len(mylist) ->3
for item in mylist:   
    print (item, "times Python")
   

[1, 2] times Python
[3, 6] times Python
[4, 5] times Python

# breaking out of loops
# find the maximum number below 1000 that divides by 12
for n in range(1000, 0, -1):
    print(n)
    div = n % 12
    print(div)
    if div == 0:
        print (n)
        break

1000
4
999
3
998
2
997
1
996
0
996

Q1)Why use break above?

cv = [[0.1,1],[0.5,11],[0.8,3]]
cw=0.6

#calculate overall score list for single criterion

dlist = []
for i in cv:
    dlist = dlist +i
    print(dlist)
    
   # overall = i*cw
   #print(overall)
    
overalls=[]
for i in dlist:
    overall= i*cw
    overalls.append(overall)
    
print(overalls)    
#for i in range(0, len(cv)):
#    print(i)

[0.1, 1]
[0.1, 1, 0.5, 11]
[0.1, 1, 0.5, 11, 0.8, 3]
[0.06, 0.6, 0.3, 6.6, 0.48, 1.7999999999999998]

cv = [0.1,0.5,0.8]
cw=0.6

overall =[]

for i in range(0, len(cv)):
    overall.append(cv[i]*cw)
    
print (overall)

[0.06, 0.3, 0.48]

cv1= [0.1,0.5,0.8]
cv2 = [0.2,0.3,0.4]
cw=[0.6, 0.4]
overalls=[]



#check if the both criterion has the equal number of elements
#calculate overall score list for criteria

cv1= [0.1,0.5,0.8]
cv2 = [0.2,0.3,0.4]
cw=[0.6, 0.4]
overalls=[]

cw[1]

if len(cv1)==len(cv2):
    for i in range(0,len(cv1)):                
        overall = cv1[i]*0.6+cv2[i]*0.4
        
        overalls.append(overall)
    print(overalls)
else:
    print("Criteria lists are not equal!")

[0.14, 0.42, 0.64]