chapter5-loops-iteration

# finite, infinite, continue, break
while True: # must use'True', not 'true'; 'while', not 'While'
    line = raw_input('> ') # "print this!"
    if line[0] == "#": # don't print this
        continue # it ends the current iteration
        # and jumps back to the "top" of the loop to start the next iteration
    if line == 'done':
        break # it ends the current iteration and GET OUT OF the iteration
        # the output is "DONE!", case sensitive
    print line
print 'DONE!'

# for loop
friends = ['Joseph', 'Glenn', 'Sally']
for i in friends: # i is iteration variable in loop and friends are variables
    print 'Happy New Year:', i
print 'Done!' # ctrl + x is delete line; this print is not in the body of the for loop

# counting and summing
count = 0
for i in [3,5,76,24,0,97]:
    # while we do not use i in the loop
    # it caused the loop body to be executed once for each of the values in the list
    count = count + 1
print "Count:", count

sumup = 0
for i in [3,5,76,24,0,97]:
    sumup = sumup + i
    #In this loop we do use the iteration variable #Instead of simply adding one to the count as in the previous loop, 
    #we add the actual number, the variable sumup is the “running total of the values so far”   # i is a  accumulator
print "The sum of list is:", sumup

# Maximum and minimum 
largest = None
print "Before:", largest
for i in [3, 41, 12, 9, 74, 15]:
    if largest is None or i > largest: # see a value that is larger than the “largest so far”. 
        largest = i # next line no block means if clause is ends in this line
    print "Loop:", i, largest # when i is 12, which is less than the largest number so far 41, so not update largest 
print "After:", largest

def min(values):
    smallest = None
    for i in values:
        if smallest is None or i < smallest:
            smallest = i
    return smallest  # 'return' only used in def, loop used print
print min('book')

# len(), sum(), max(), min(),  mid-point check
# initialize: An assignment that gives an initial value to a variable that will be updated

# Exercises 1: keeep calculating until put done; if bad input, skip and continue enter next and continue calculating
total = 0
count = 0
try:
    while True:
        enters = raw_input('Enter a number:')
        if enters == 'done':
            break
        total = total + float(enters)
        count = count + 1
        avg = total/count
    print total, count, avg
except:
    print "Invalid input"
    while True:
        enters = raw_input('Enter a number:')  
        #if bad input happen twice, how to revise the code?
        if enters == 'done':
            break
        total = total + float(enters)
        count = count + 1
        avg = total/count
    print total, count, avg
    
# Exercises 2:prompts for a list of numbers 
total = 0 # must use 0 to initialize when calculate ( total = total + float(i))
count = 0
mini = None # can use None to initialize if only assgining, not calculating ( mini = i)
maxi = None # Must be None(reserved), not none(variable)
try:
    enters = raw_input('Enter a number:') #4,5,bad data,7,done (NO SPACE!!)
    enterlist = enters. split(',') #['4', '5', 'bad data', ' 7', ' done']
    for i in enterlist: #erro "unexpected indent" if this line has block
        if i == 'done':
            break      # ignore the enters after "done" was put
        total = total + float(i)
        count = count + 1
        if mini is None or i < mini:
            mini = i
        if maxi is None or i > maxi:
            maxi = i
        sub_enterlist = enterlist[count+1:] # [] position starting from '0'
    print total, count, mini, maxi
except:
    for i in sub_enterlist: # if bad data, skip and continue from next number
        if i == 'done':  
            break # jump out of loop means starting from the line that has no block compared with for clause
        total = total + float(i)   # bad data can only appear once because only one except clause?
        count = count + 1
        if mini is 0 or i < mini:
            mini = i
        if maxi is 0 or i > maxi:
            maxi = i
    print total, count, mini, maxi # this is the line which means for loop ends (NO BLOCK)

# Exercises 3
maximum = None
minimum = None
try:
    while True:
        num = raw_input("Enter a number: ")
        if num == "done" :
            break
        if maximum is None or int(num) > maximum:
            maximum = int(num)
        if minimum is None or int(num) < minimum:
            minimum = int(num)
    print "Maximum is", maximum
    print "Minimum is", minimum
except:
    print "Invalid input"
    while True:
        num = raw_input("Enter a number: ")
        if num == "done" :
            break
        if maximum is None or int(num) > maximum:
            maximum = int(num)
        if minimum is None or int(num) < minimum:
            minimum = int(num)
    print "Maximum is", maximum
    print "Minimum is", minimum