I would like
to check if a string can be a float before I attempt to convert it to a float. This way, if the
string is not float, we can print an error message and exit instead of crashing the
program.
so when the user inputs something, I wanna see if its a float so it will print "true" if its not then it will print"false" rather than crashing. I don't want to use built in functions for this. I need to make my own function for this.
I tried :
import types
def isFloat():
x = raw_input("Enter: ")
if(x) == float:
print("true")
if(x) == str:
print("false")
isFloat()
I don't know if its true or not but it wont work it wont print anything either
The recommended thing to do here is to try it:
try:
f = float(x)
print("true")
except ValueError:
# handle error here
print("false")
This underscores the Python philosophy "It's better to ask for forgiveness than for permission".
The only reliable way to figure out whether a string represents a float is to try to convert it. You could check first and convert then, but why should you? You'd do it twice, without need.
Consider this code:
def read_float():
"""
return a floating-point number, or None
"""
while True:
s = raw_input('Enter a float: ').strip()
if not s:
return None
try:
return float(s)
except ValueError:
print 'Not a valid number: %r' % s
num = read_float()
while num is not None:
... do something ...
print 'Try again?'
num = read_float()
Related
I'm learning how to code using Codecademy and I am really stuck on a question, and would love to be pointed in the right direction!
The code for the most part works, I just cannot get it to respond to the .match_reply function correctly. The idea is that the chatbot should identify the regex in self.alienbabble and respond with the appropriate answer. However, it is bugging out with an infinite recursion of all the responses of that function.
# importing regex and random libraries
import re
import random
class AlienBot:
# potential negative responses
negative_responses = ("no", "nope", "nah", "naw", "not a chance", "sorry")
# keywords for exiting the conversation
exit_commands = ("quit", "pause", "exit", "goodbye", "bye", "later")
# random starter questions
random_questions = (
"Why are you here? ",
"Are there many humans like you? ",
"What do you consume for sustenance? ",
"Is there intelligent life on this planet? ",
"Does Earth have a leader? ",
"What planets have you visited? ",
"What technology do you have on this planet? "
)
def __init__(self):
self.alienbabble = {'describe_planet_intent': '.*\s*your planet.*','answer_why_intent': 'why\sare.*', 'cubed_intent': '.*cube.*(\d+)'}
# Define .greet() below:
def greet(self):
self.name = input("Hello. What is your name?")
will_help = input(f"Hi {self.name}, I'm Etcetera. I'm not from this planet. Will you help me learn about your planet? ")
if will_help in self.negative_responses:
print ("Ok, have a nice Earth day!")
return
self.chat()
# Define .make_exit() here:
def make_exit(self, reply):
for word in self.exit_commands:
if word in reply:
print ("Ok, have a nice Earth day!")
return True
# Define .chat() next:
def chat(self):
reply = input(random.choice(self.random_questions)).lower()
while not self.make_exit(reply):
reply = input(self.match_reply(reply))
# Define .match_reply() below:
def match_reply(self, reply):
for key, value in self.alienbabble.items():
intent = key
regex = value
#regex = 'describe_planet_intent'
#reply = input(random.choice(self.random_questions)).lower()
found_match = re.match(regex, reply)
if found_match and intent == 'describe_planet_intent':
return self.describe_planet_intent()
elif found_match and intent == 'answer_why_intent':
return self.answer_why_intent()
elif found_match and intent == 'cubed_intent':
return self.cubed_intent(found_match.groups()[0])
else:
return self.no_match_intent()
# Define .describe_planet_intent():
def describe_planet_intent(self):
responses = ("My planet is a utopia of diverse organisms and species. ", "I am from Opidipus, the capital of the Wayward Galaxies. ")
return random.choice(responses)
# Define .answer_why_intent():
def answer_why_intent(self):
responses = ("I come in peace. ", "I am here to collect data on your planet and its inhabitants. ", "I heard the coffee is good. ")
return random.choice(responses)
# Define .cubed_intent():
def cubed_intent(self, number):
number = int(number)
cubed_number = number * number * number
return (f"The cube of {number} is {cubed_number}. Isn't that cool? ")
# Define .no_match_intent():
def no_match_intent(self):
responses = ("Please tell me more. ", "Tell me more! ", "Why do you say that? ", "I see. Can you elaborate? ", "Interesting. Can you tell me more? ", "I see. How do you think? ", "Why? ", "How do you think I feel when you say that? ")
return random.choice(responses)
# Create an instance of AlienBot below:
my_bot = AlienBot()
my_bot.greet()
I feel like there is a really simple solution to this, I've only been coding for 1 week so this is really new to me, and I appreciate your help :)
The answer is indeed simple. Let's reduce your code to a minimally reproducible one:
def match_reply(self, reply):
for key, value in self.alienbabble.items():
# I omitted the 3 lines that were here - defining 'intent', 'regex_pattern' and 'regex' -
# since at this point they're yet not used
reply = input(self.match_reply(reply)) # oops! self.match_reply is called again!
As you can see, you recursively call self.match_reply without anything to stop it.
EDIT:
There are another 2 things you need to fix:
Let's change match_reply:
a. Let's give it the more appropriate name match_alien_response.
b. Let's make it do what it should: just match a reply. Thus, we don't need it to get another input from the user.
c. Let's make sure it iterates all the keys in alienbabble and doesn't return immediately.
d. We need to use re.findall to get all matches in a string
All these changes give us the following code:
def match_alien_response(self, userReply):
found = False
for intent, regPattern in self.alienbabble.items():
found_match = re.findall(regPattern, userReply)
if found_match and intent == 'describe_planet_intent':
return self.describe_planet_intent()
elif found_match and intent == 'answer_why_intent':
return self.answer_why_intent()
elif found_match and intent == 'cubed_intent':
return self.cubed_intent(found_match[0])
if not found:
return self.no_match_intent()
Inside no_match_intent, it should be responses = instead of responses:
I am new to python.
My Issue- need to terminate the raw_input if no input is passed
I am basically asking user for number of key-value pairs to be added to dictionary. Then adding the key-value pairs in dictionary. Later querying the dictionary which should result value if key exist, else print Not found.
I searched the Stack Overflow and found solution in terms of timer but I am trying to use ord function to get ascii value of string and check it against null that is ascii value of 0. My code does not seem to terminate, please advice on necessary changes in code.
Please find the code that I am using in the program:
def convert_to_ascii(text):
return "".join(str(ord(char)) for char in text)
n=int(raw_input().rstrip())
phonebook = dict(raw_input().split() for i in range(n))
print phonebook
list1=[]
while True:
choice = raw_input()
temp=convert_to_ascii(choice)
print temp
if temp != '0':
list1.append(choice)
else:
break
for word in list1:
if word in phonebook :
print '{0}={1}'.format(word,phonebook[word])
else:
print 'Not found'
You should have the empty string '' instead of '0' as your check. This code worked for me. I also added some prints in the raw_inputs to help me look through your code, but the only change that matters is the '0' to '':
def convert_to_ascii(text):
return "".join(str(ord(char)) for char in text)
n=int(raw_input('How many entries in your phonebook?\n').rstrip())
phonebook = dict(raw_input('Please enter "[name] [number]" for entry '+str(i+1)+':\n').split() for i in range(n))
print phonebook
list1=[]
while True:
choice = raw_input('Who do you want to choose?\n')
temp=convert_to_ascii(choice)
if temp != '': #<-- changed to empty string from '0'
list1.append(choice)
else:
break
for word in list1:
if word in phonebook :
print '{0}={1}'.format(word,phonebook[word])
else:
print word,'was not found'
I have the following function defined:
def displayHand(hand):
"""
Displays the letters currently in the hand.
For example:
>>> displayHand({'a':1, 'x':2, 'l':3, 'e':1})
Should print out something like:
a x x l l l e
The order of the letters is unimportant.
hand: dictionary (string -> int)
"""
for letter in hand.keys():
for j in range(hand[letter]):
print letter, # print all on the same line
print '' # print an empty line
Now, I want to print the following:
Current hand: a b c
To do this, I try to do:
print "Current hand: ", displayHand({'a':1, 'b':1, 'c':1})
And I get:
Current hand: a b c
None
I know that None is printed cause I am calling the print function on the displayHand(hand) function, which doesn't return anything.
Is there any way to get rid of that "None" without modifying displayHand(hand)?
if you want to use your function in a print statement, it should return a string and not print something itself (and return None) - as you would do in a __str__ method of a class. something like:
def displayHand(hand):
ret = ''
for letter in hand.keys():
for j in range(hand[letter]):
ret += '{} '.format(letter) # print all on the same line
# ret += '\n'
return ret
or even
def displayHand(hand):
return ''.join(n*'{} '.format(k) for k,n in hand.items() )
When you trail a print with a ,, the next print will appear on the same line, so you should just call the two things on separate lines, as in:
def printStuff():
print "Current hand: ",
displayHand({'a':1, 'b':1, 'c':1})
Of course you could just adapt this and create a method like:
def printCurrentHand(hand):
print "Current hand: ",
displayHand(hand)
The only way to do this (or I believe the only way to do this) is to use return instead of print in your displayhand() function. Sorry if I didn't answer your question.
Your function 'displayHand' does not have to print the output,
it has to return a string.
def displayHand(hand):
mystring=''
for letter in hand.keys():
for j in range(hand[letter]):
mystring+= letter # concatenate all on the same line
return mystring
BUT, you have to check the '.keys' command help as the order of the input (a/b/c) may not be respected
I wrote a program where you guess a randomly generated number between 1 and 100:
from random import randint
play='y'
print 'Guess a number between 1 and 100'
while play=='y':
x = randint(1,100)
guess=1000
while guess != x:
guess=input('Guess: ')
if guess < x:
print 'Higher'
if guess > x:
print 'Lower'
print 'You got it! Good Job! The number was ' + str(x)
play=raw_input('Would you like to play again(y/n)?: ')
raw_input("Press <enter> to exit")
when the user enters a guess that is not an integer how do I print That is not a number, then allow them to continue guessing?
Use a while True loop to repeat the question until it breaks. Only way to break the loop is if try does not raise a ValueError. int() raises an error when it gets something like 'hello' or '1.2'.
Also, use raw_input instead of input (note: raw_input assigns a string to guess).
while True:
guess=raw_input('Guess: ')
try:
int(guess)
break
except ValueError:
print '\nNot an int, try again.'
More specifically, insert this after while guess != x: and before if guess < x.
I'm working on a number guessing game and can't seem to get my loop to work while utilizing a function. I was manually typing out conversion under each if/elif in the block, but that was tedious and only checking for integers - string inputs couldn't read and broke the system.
I tried creating a conversion function to check the values and determine if it was an integer or string and change the variable type accordingly. However this results in an infinite loop fo line 18.
Can someone point out what I'm doing wrong here?
Heads up, I do have the random.py script from Python.org and am importing it so the game plays differently each time.
from random import randint
print 'Hello, my name is Skynet. What\'s yours?'
myName = raw_input()
print 'Good to meet you, ' + myName + '! Let\'s play a game.'
print 'I\'m thinking of a number between between 1 and 20, can you guess it?'
pcNum = randint(1,20)
myNum = raw_input()
def checkNum(myNum):
try:
int(myNum)
except ValueError:
returnVAL = 'That\'s not a number I know, try again.'
else:
returnVAL = int(myNum)
return returnVAL
while myNum != pcNum:
if myNum > pcNum:
print 'That\'s too high! Try again.'
myNum = raw_input()
checkNum(myNum)
else:
print 'That\'s too low! Try again.'
myNum = raw_input()
checkNum(myNum)
if myNum == pcNum:
print 'Good job, my number was ' + str(pcNum) + ' too! Good job, ' + myName
Any input is appreciated. I did some browsing here and got some a better idea of how to pull this off, or so I thought, and now here I am asking. First post!
print "I'm thinking of a number between between 1 and 20, can you guess it?"
while True:
guess = raw_input("What's your guess? ")
try:
guess = int(guess, 10)
except ValueError:
print "That's not a number I know, try again."
continue
if guess == pcNum:
...
break
elif guess > pcNum:
...
else:
...
Don't mix responsibilities. It is wrong to have myNum be both a number and an error message.
Also, think what you want to do when a user enters a non-number. In your case, the user's guess is "That's not a number I know, try again.", and it's being compared to pcNum; this makes no sense. If it was me, I would want the user to enter the number again. So rather than checkNum, I want input_valid_integer:
def input_valid_integer():
result = None
while result is None:
text = raw_input()
try:
result = int(text)
except ValueError:
print 'That\'s not a number I know, try again.'
return result