Python 3.3：如何从每行的第一个单词中提取第一个字母？

Question

I need assistance for this problem I'm having. I'm trying to get my program to grab the first Letter from the first Word on every single line and print them in a single string.

For example if I type the following words in a block of text:

People like to eat pie for three reasons, it tastes delicious. The taste is unbelievable, next pie makes a
great dessert after dinner, finally pie is disgusting.

The result should be "Pg" this is a small example but you get the idea.

I started on the code but I'm clueless on where to go.

#Prompt the user to enter a block of text.
done = False
print("Enter as much text as you like. Type EOF on a separate line to finish.")
textInput = ""
while(done == False):
    nextInput= input()
    if nextInput== "EOF":
        break
    else:
        textInput += nextInput

#Prompt the user to select an option from the Text Analyzer Menu.
print("Welcome to the Text Analyzer Menu! Select an option by typing a number"
    "\n1. shortest word"
    "\n2. longest word"
    "\n3. most common word"
    "\n4. left-column secret message!"
    "\n5. fifth-words secret message!"
    "\n6. word count"
    "\n7. quit")

#Set option to 0.
option = 0

#Use the 'while' to keep looping until the user types in Option 7.
while option !=7:
    option = int(input())

#I have trouble here on this section of the code.
#If the user selects Option 4, extract the first letter of the first word
    #on each line and merge into s single string.
    elif option == 4:
        firstLetter = {}
        for i in textInput.split():
            if i < 1:
                print(firstLetter)

Answer 1

You can store the inputs as a list, then get the first character from each list:

textInput = []
while(done == False):
    nextInput= input()
    if nextInput== "EOF":
       break
    else:
        textInput.append(nextInput)



...


print ''.join(l[0] for l in textInput)

Answer 2

I'd start by making a list of lines instead of a single string:

print("Enter as much text as you like. Type EOF on a separate line to finish.")

lines = []

while True:
    line = input()

    if line == "EOF":
        break
    else:
        lines.append(line)

Then, you can get the first letters with a loop:

letters = []

for line in lines:
    first_letter = line[0]
    letters.append(first_letter)

print(''.join(letters))

Or more concisely:

print(''.join([line[0] for line in lines]))

Answer 3

This is very simple:

with open('path/to/file') as infile:
    firsts = []
    for line in infile:
        firsts.append(line.lstrip()[0])
print ''.join(firsts)

Of course, you could do the same thing with the following two-liner:

with open('path/to/file') as infile:
    print ''.join(line.lstrip()[0] for line in infile)

Hope this helps