#
# Strings
#
# Practice 
#

# Where are we? 

if while for :
str list 
str 
list
tuple 
set 



Preliminary notes: 
- Based on (part of) Chapter 7
  (which also discusses files).            
  Specifically: 
  upper(), lower(), replace(), join(), split() 
- Essentially - a toolbox. 
  Python string methods (search for "String methods")
  https://docs.python.org/3/library/stdtypes.html
  Here: only some very common methods.   
- This does not pertain the issue of 
  string formatting. 
- Use only the studied material.   


# Q. 1  upper() and lower() 
# Write a program that finds the frequency 
# of all words in a given book, case insensitive. 
# Assume the text does not include punctuation marks. 

book = "The man the sheep the Man the SHEEP"
book = book.lower()
word = "" 
words = [] 
for c in book: 
    if c != " ": 
        word = word + c 
    else: 
        words = words + [word]
        word = "" 
words = words + [word]
freqs = [] 
for word in words: 
    pair = [word, words.count(word)]
    if pair not in freqs: 
        freqs = freqs + [pair]
print(freqs)



# Q. 2 - replace() 
# Write a program that given a string of 
# punctuation marks, ",.-", deletes them 
# all from a given sentence, save - used 
# as hyphen. 

s = "Sometime, I will meet $ road-runner. Perhaps - who knows."
s = s.replace("-", '$')
s = s.replace(" $ ", " - ")
print(s)
puncts = ",.-"
for punct in puncts: 
    for i in range(s.count(punct)): 
        s = s.replace(punct, "")
s = s.replace("$", "-")
print(s)


# Q. 3 - join() 
# Write a program that receives words from the 
# user, one after another, until 1 is entered. 
# The program prints the words separted one 
# from the other by a single space. 

word = input("Please enter a word: ")
words = [] 
while word != "1":
    words = words + [word]
    word = input("Please enter a word: ")
print(" ".join(words))




# Q. 4 - split() 
# Write a program that receives a list of 
# full names in the following patterns: 
# fullnames = ['Humberto L. Good', 
#              'Tanya M. Nelson',
#              'Andrew D. Hendrix'] 
# The program rearranges the names such that 
# the surname appears first: 
# fullnames = ['Good Humberto L.', 
#              'Nelson Tanya M.',
#              'Hendrix Andrew D.'] 

fullnames = ['Humberto L. Good', 
             'Tanya M. Nelson',
             'Andrew D. Hendrix'] 
for i in range(len(fullnames)): 
    names = fullnames[i].split()
    fullnames[i] = names[2] + " " + names[0] + " " + names[1]
print(fullnames)









# Q. 5
# Write a program that given a sentence, 
# put in parentehsis all words including 
# the letter e, case insensitive. 

sent = 'To be or not to bE' 
words = sent.split()
newS = "" 
for word in words: 
    if "e" in word.lower(): 
        newS = newS + "(" + word + ") "
    else: 
        newS = newS + word + " "
newS = newS[:-1]
print(newS + "-")




# Q. 6 
# (a) given a text with email addresses, write a program 
# that constructs a list including all 
# the email addresses. 

s = '''Yesterday I received an email from 
    123@abc.com. This was after I received
    an email from 456@def.ac.il. I hope 
    that someday someone with the address
    789@ghi.org will write to me. ''' 
words = s.split(' ')
emails = [] 
for word in words: 
    if "@" in word and "." in word: 
        emails = emails + [word]
print(emails)

regex 


(b) Now include in the list only those 
    email addresses preceeded by the 
    word from. 

s = '''123@abc.com. This was after I received
    an email from 456@def.ac.il. I hope 
    that someday someone with the address
    789@ghi.org will write to from ''' 
words = s.split()
print(words)
emails = [] 
for i in range(len(words)): 
    if ("@" in words[i] and "." in words[i] 
        and words[i-1] == "from"): 
        emails = emails + [words[i]]
print(emails)

myS = '''from 
  XXX'''
print(myS.split(' '))