I need to convert a string inputed by a user into morse code. The way our professor wants us to do this is to read from a morseCode.txt file, seperate the letters from the morseCode into two lists, then convert each letter to morse code (inserting a new line when there is a space).
I have the beginning. What it does is reads the morseCode.txt file and seperates the letters into a list [A, B, ... Z] and the codes into a list ['– – . . – –\n', '. – . – . –\n'...].
We haven't learned "sets" yet, so I can't use that. How would I then take the string that they inputed, go through letter by letter, and convert it to morse code? I'm a bit caught up. Here's what I have right now (not much at all...)
EDIT: completed the program!
# open morseCode.txt file to read
morseCodeFile = open('morseCode.txt', 'r') # format is <letter>:<morse code translation><\n>
# create an empty list for letters
letterList = []
# create an empty list for morse codes
codeList = []
# read the first line of the morseCode.txt
line = morseCodeFile.readline()
# while the line is not empty
while line != '':
# strip the \n from the end of each line
line = line.rstrip()
# append the first character of the line to the letterList
letterList.append(line[0])
# append the 3rd to last character of the line to the codeList
codeList.append(line[2:])
# read the next line
line = morseCodeFile.readline()
# close the file
morseCodeFile.close()
try:
# get user input
print("Enter a string to convert to morse code or press <enter> to quit")
userInput = input("")
# while the user inputs something, continue
while userInput:
# strip the spaces from their input
userInput = userInput.replace(' ', '')
# convert to uppercase
userInput = userInput.upper()
# set string accumulator
accumulateLetters = ''
# go through each letter of the word
for x in userInput:
# get the index of the letterList using x
index = letterList.index(x)
# get the morse code value from the codeList using the index found above
value = codeList[index]
# accumulate the letter found above
accumulateLetters += value
# print the letters
print(accumulateLetters)
# input to try again or <enter> to quit
print("Try again or press <enter> to quit")
userInput = input("")
except ValueError:
print("Error in input. Only alphanumeric characters, a comma, and period allowed")
main()
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I can't leave this question in this state with that final code in the question hanging over me...
dan: here's a much neater and shorter version of your code. It would be a good idea to look at how this is done and code more this way in future. I realise you probably have no further need of this code, but learning how you should do it is a good idea. Some things to note:
There are only two comments - and even the second is not really necessary for someone familiar with Python, they'll realise NL is being stripped. Only write comments where it adds value.
The with statement (recommended in another answer) removes the bother of closing the file through the context handler.
Use a dictionary instead of two lists.
A generator comprehension ((x for y in z)) is used to do the translation in one line.
Wrap as little code as you can in a try/except block to reduce the probability of catching an exception you didn't mean to.
Use the input() argument rather than print()ing first - Use '\n' to get the new line you want.
Don't write code across multiple lines or with intermediate variables like this just for the sake of it:
a = a.b()
a = a.c()
b = a.x()
c = b.y()
Instead, write these constructs like this, chaining the calls as is perfectly valid:
a = a.b().c()
c = a.x().y()
code = {}
with open('morseCode.txt', 'r') as morse_code_file:
# line format is <letter>:<morse code translation>
for line in morse_code_file:
line = line.rstrip() # Remove NL
code[line[0]] = line[2:]
user_input = input("Enter a string to convert to morse code or press <enter> to quit\n")
while user_input:
try:
print(''.join(code[x] for x in user_input.replace(' ', '').upper()))
except KeyError:
print("Error in input. Only alphanumeric characters, a comma, and period allowed")
user_input = input("Try again or press <enter> to quit\n")
Why not just iterate through the string?
a_string="abcd"
for letter in a_string:
print letter
returns
a
b
c
d
So, in pseudo-ish code, I would do this:
user_string = raw_input()
list_of_output = []
for letter in user_string:
list_of_output.append(morse_code_ify(letter))
output_string = "".join(list_of_output)
Note: the morse_code_ify function is pseudo-code.
You definitely want to make a list of the characters you want to output rather than just concatenating on them on the end of some string. As stated above, it's O(n^2): bad. Just append them onto a list, and then use "".join(the_list).
As a side note: why are you removing the spaces? Why not just have morse_code_ify(" ") return a "\n"?
Use 'index'.
def GetMorseCode(letter):
index = letterList.index(letter)
code = codeList[index]
return code
Of course, you'll want to validate your input letter (convert its case as necessary, make sure it's in the list in the first place by checking that index != -1), but that should get you down the path.
For the actual processing I'd keep a string of finished product, and loop through each letter in the string they have entered. I'd call a function to convert a letter to morse code, then add it to the string of existing morse code.
finishedProduct = []
userInput = input("Enter text")
for letter in userInput:
finishedProduct.append( letterToMorseCode(letter) )
theString = ''.join(finishedProduct)
print(theString)
You could either check for space in the loop, or in the function that is called.
Create a lookup table first:
morse = [None] * (ord('z') - ord('a') + 1)
for line in moreCodeFile:
morse[ord(line[0].lower()) - ord('a')] = line[2:]
Then convert using the table:
for ch in userInput:
print morse[ord(ch.lower()) - ord('a')]
# Open the file
f = open('morseCode.txt', 'r')
# Read the morse code data into "letters" [(lowercased letter, morse code), ...]
letters = []
for Line in f:
if not Line.strip(): break
letter, code = Line.strip().split() # Assuming the format is <letter><whitespace><morse code><newline>
letters.append((letter.lower(), code))
f.close()
# Get the input from the user
# (Don't use input() - it calls eval(raw_input())!)
i = raw_input("Enter a string to be converted to morse code or press <enter> to quit ")
# Convert the codes to morse code
out = []
for c in i:
found = False
for letter, code in letters:
if letter == c.lower():
found = True
out.append(code)
break
if not found:
raise Exception('invalid character: %s' % c)
# Print the output
print ' '.join(out)
A couple of things for ya:
The loading would be "better" like this:
with file('morsecodes.txt', 'rt') as f:
for line in f:
line = line.strip()
if len(line) > 0:
# do your stuff to parse the file
That way you don't need to close, and you don't need to manually load each line, etc., etc.
for letter in userInput:
if ValidateLetter(letter): # you need to define this
code = GetMorseCode(letter) # from my other answer
# do whatever you want
# Retain a map of the Morse code
conversion = {}
# Read map from file, add it to the datastructure
morseCodeFile = file('morseCode.txt')
for line in moreCodeFile:
conversion[line[0]] = line[2:]
morseCodeFile.close()
# Ask for input from the user
s = raw_input("Please enter string to translate")
# Go over each character, and print it the translation.
# Defensive programming: do something sane if the user
# inputs non-Morse compatible strings.
for c in s:
print conversion.get(c, "No translation for "+c)
Source: Stackoverflow.com