I am trying to shorten the process of making lists through the use of a defined function where the variable is the list name. When run, the code skips the user input.
When I run my code, the section of user input seems to be completely skipped over and as such it just prints an empty list. I've tried messing around with the variable names and defining things at different points in the code. Am I missing a general rule of Python or is there an obvious error in my code I'm missing?
def list_creation(list_name):
list_name = []
num = 0
while num != "end":
return(list_name)
num = input("Input a number: ")
print("To end, type end as number input")
if num != "end":
list_name.append(num)
list_creation(list_Alpha)
print("This is the first list: " + str(list_Alpha))
list_creation(list_Beta)
print("This is the second list: " + str(list_Beta))
I want the two seperate lists to print out the numbers that the user has input. Currently it just prints out two empty lists.
You need to move the return statement to the end of the function, because return always stops function execution.
Also, what you're trying to do (to my knowledge) is not possible or practical. You can't assign a variable by making it an argument in a function, you instead should remove the parameter list_name altogether since you immediately reassign it anyway, and call it like list_alpha = list_creation()
As a side note, the user probably wants to see the whole "To end, type end as number input" bit before they start giving input.
Dynamically defining your variable names is ill advised. With that being said, the following code should do the trick. The problem consisted of a misplaced return statement and confusion of variable name with the variable itself.
def list_creation(list_name):
g[list_name] = []
num = 0
while num != "end":
num = input("Input a number: ")
print("To end, type end as number input")
if num != "end":
g[list_name].append(num)
g = globals()
list_creation('list_Alpha')
print("This is the first list: " + str(list_Alpha))
list_creation('list_Beta')
print("This is the second list: " + str(list_Beta))
There are a couple of fundamental flaws in your code.
You redefine list_name which is what Alpha and Beta lists are using as the return.(list_name = [] disassociates it with Alpha and Beta so your function becomes useless.)
You return from the function right after starting your while loop(so you will never reach the input)
In your function:
list_Alpha = []
list_Beta = []
def list_creation(list_name):
# list_name = [] <-- is no longer Alpha or Beta, get rid of this!
num = 0
...
The return should go at the end of the while loop in order to reach your input:
while num != "end":
num = input("Input a number: ")
print("To end, type end as number input")
if num != "end":
list_name.append(num)
return(list_name)
Related
I have tried this several different ways, I am still fairly new to Python so go easy on me. I am trying to execute a script where the user can choose to import a list from a plaintext file, or input a list manually, and the script will return the median and mode of the data.
The problem I am having is that my median and mode functions are not recognizing the reference to the raw data, and the main function isn't recognizing the median and mode from their respective functions.
I guess it's safe to say I am not calling these functions correctly, but frankly I just dont know how. Any help here would be much appreciated.
def choice():
##Choose user input type
start = input("Please select your input method by typing 'file' or 'manual' in all lower-case letters: ")
# Import File Type
userData = []
if start == "file":
fileName = input("Please enter the file name with the file's extension, e.g. ' numbers.txt': ")
userData = open(fileName).read().splitlines()
return userData
userData.close()
# Manual Entry Type
elif start == "manual":
while True:
data = float(input("Please enter your manual data one item at a time, press enter twice to continue: "))
if data == "":
break
userData = data
return userData
# Error
else:
print("You have entered incorrectly, please restart program")
def median(medianData):
numbers = []
for line in (choice(userData)):
listData = line.split()
for word in listData:
numbers.append(float(word))
# Sort the list and print the number at its midpoint
numbers.sort()
midpoint = len(numbers) // 2
print("The median is", end=" ")
if len(numbers) % 2 == 1:
medianData = (numbers[midpoint])
return medianData
else:
medianData = ((numbers[midpoint] + numbers[midpoint - 1]) / 2)
return medianData
def mode(modeData):
words = []
for line in (choice(userData)):
wordsInLine = line.split()
for word in wordsInLine:
words.append(word.upper())
theDictionary = {}
for word in words:
number = theDictionary.get(word, None)
if number == None:
theDictionary[word] = 1
else:
theDictionary[word] = number + 1
theMaximum = max(theDictionary.values())
for key in theDictionary:
if theDictionary[key] == theMaximum:
theMaximum = modeData
break
return modeData
def main():
print("The median is", (median(medianData)))
print("The mode is", (mode(modeData)))
Welcome! I think you need to read up a bit more on how functions work. The argument when you define a function is a "dummy" local variable whose name matters only in the definition of a function. You need to supply it a variable or constant whose name makes sense where you use it. It is a very good analogy to functions in mathematics which you may have learned about in school. (Note that these points are not specific to python, although the detailed syntax is.)
So when you have def median(medianData) you need to use medianData in the definition of the function, not userData, and when you call median(somevar) you have to make sure that somevar has a value at that point in your program.
As a simpler example:
def doubleMyVariable(x):
return 2*x
How would you use this? You could just put this somewhere in your code:
print(doubleMyVariable(3))
which should print out 6.
Or this:
z = 12
y = doubleMyVariable(z)
print(y)
which will print 12.
You could even do
z = 36
x = doubleMyVariable(z)
which will assign 72 to the variable x. But do you see how I used x there? It has nothing to do with the x in the definition of the function.
def main():
for row in range (7):
assignment = int(1)
if row == 1:
for assignment_number in range(0,8):
assignment_number+1
for i in range(0,7):
assignment_mark = float(input(("Please enter your mark for assginment" assignment_number,": "))
assignment_weight = float(input("Please enter the total weight percentage for the assignment: "))
main()
So this is my code above,
I'm basically trying to work out how I could say for each input variable "Please enter your mark for assignment x (from 1 up to 7).
Which will loop, so once they enter it for assignment 1, it then asks the same question for assignment 2.
I hope this makes some sense. I'm new to programming in general and this just happens to also be my first post on stack! Be gentle (:
Thanks!
There are a few problems with your code:
assignment_number+1 without assigning it to a variable does nothing, and even if you did, that value would be lost after the loop. If you want to offset the numbers by one, you can just use range(1, 8) or do +1 when you actually need that value of that variable
in your second loop, your loop variable is i, but you are using assignment_number from the previous loop, which still has the value from the last execution, 7
you have to store the values for assignments_mark and assignment_weight somewhere, e.g. in two lists, a list of tuples, or a dict of tuples; since assignment numbers start with 1 and not 0, I'd recommend a dict
You can try something like this, storing the marks and weights for the assignments in a dictionary:
assignments = {}
for i in range(7):
assignment_mark = float(input("Please enter your mark for assginment %d: " % (i+1)))
assignment_weight = float(input("Please enter the total weight percentage for the assignment: "))
assignments[i+1] = (assignment_mark, assignment_weight)
print(assignments)
Let the loop do the counting, then use string formatting.
And you only need a single loop to collect each pair of events
from collections import namedtuple
Assignment = namedtuple("Assignment", "mark weight")
assignments = []
for idx in range(7):
print("Please enter data for assignment {}".format(idx+1))
mark = float(input("mark: "))
weight = float(input("weight:"))
assignments.append(Assignment(mark, weight))
print(assignments)
I want to write 2 functions. One function that takes input from a user and adds it to a list. The 2nd function takes the list returned from the 1st function and prints out each element separated by a space. I think I am close, but something isn't right. Typing -999 doesn't stop the loop, and I can't tell if I am calling the functions correctly...
Any ideas?
def listFunc():
num = 0
list1 = []
while num != -999:
x = int(input('Enter a number, -999 to quit: '))
list1.append(x)
return list1
def formatFunc(y):
final = str(y)
' '.join(final)
print(final)
formatFunc(listFunc())
It should be the same variable used in while loop.
num = int(input('Enter a number, -999 to quit: '))
if num != -999:
list1.append(num)
and
# final = str(y) This is not required, why cast list as str
final = ' '.join(final)
x = int(input('Enter a number, -999 to quit: '))
list1.append(x)
num=x
will work!
You are calling the functions correctly if you intend on printing the inputs of listfunc. However the inputs will not be saved to a variable in global scope and will thus be locked out from any future use.
Additionally, listfunc currently does no input validation. It is possible to input any strings in the input. The while loop doesn't end because the condition in the while is never met.
Rewriting it according to your conditions yields:
def listfunc():
someList = []
while True:
x = input("Enter a number, exit to quit")
if 'exit' in x.lower():
break
elif x.isdigit():
someList.append(x)
else:
print("Input not recognized try again")
return someList
def formatFunc(v):
print(''.join(str(i) + ' ' for i in v)
Do you see why this works?
I have a function below which is part of my big main function, what I want this function to do is that whenever called, I want the function to check if the user input is
a number or not. If it is a number it will return the number and break.
But if it is not a number I want it to loop again and again.when I try to
run it, it gives me unexpected an error:
unexpected eof while parsing
can any body help me what I am missing or how I should rearrange my code? thank you!
def getnumber():
keepgoing==True
while keepgoing:
number = input("input number: ")
result1 = number.isdigit()
if result1 == 1:
return number
break
elif keepgoing==True:
A neater and clearer what to do what you are already doing:
def getnumber():
while True:
number = input("Input number: ")
if number.isdigit():
return number
That's all you need, the extra variables are superfluous and the elif at the end makes no sense. You don't need to check booleans with == True or == 1, you just do if condition:. And nothing happens after return, your break will never be reached.
You don't need the last line:
elif keepgoing==True:
It's waiting for the rest of the file after the :.
Side note, it should be a single = in the first part, and can just be written simpler as well.
def getnumber():
while True:
number = input("input number: ")
result1 = number.isdigit()
if result1:
return number
Since you're inside the while loop, it'll keep executing. Using return will end the while loop, as will breaking and exiting the program. It will wait for input as well each time, though.
While assigning you have used keepgoing == True, I think it should be keepgoing=True
The following solution works on my machine, although I am running Python 2.7
def get_num():
while True: #Loop forever
number_str = raw_input("> Input a number: ") #Get the user input
if number_str.isdigit(): #They entered a number!
return int(number_str) #Cast the string to an integer and return it
I used raw_input rather than input, because raw_input gives you the exact string the user entered, rather than trying to evaluate the text, like input does. (If you pass the 12 to input, you'll get the number 12, but if you pass "12", you'll get the string '12'. And, if you pass my_var, you'll get whatever value was in my_var).
Anyway, you should also know that isdigit() returns whether or not the string has only digits in it and at least one character - that is not the same thing as isNumber(). For instance, "123".isdigit() is True, but "123.0".isdigit() is False. I also simplified your loop logic a bit.
The task:
Write a function called eval_loop that iteratively prompts the user, takes the resulting input and evaluates it using eval(), and prints the result.
It should continue until the user enters 'done', and then return the value of the last expression it evaluated.
My code:
import math
def eval_loop(m,n,i):
n = raw_input('I am the calculator and please type: ')
m = raw_input('enter done if you would like to quit! ')
i = 0
while (m!='done' and i>=0):
print eval(n)
eval_loop(m,n,i)
i += 1
break;
eval_loop('','1+2',0)
My code cannot return the value of the last expression it evaluated!
Three comments:
Using recursion for this means that you will eventually hit the system recursion limit, iteration is probably a better approach (and the one you were asked to take!);
If you want to return the result of eval, you will need to assign it; and
I have no idea what i is for in your code, but it doesn't seem to be helping anything.
With those in mind, a brief outline:
def eval_loop():
result = None
while True:
ui = raw_input("Enter a command (or 'done' to quit): ")
if ui.lower() == "done":
break
result = eval(ui)
print result
return result
For a more robust function, consider wrapping eval in a try and dealing with any errors stemming from it sensibly.
import math
def eval_loop():
while True:
x=input('Enter the expression to evaluate: ')
if x=='done':
break
else:
y=eval(x)
print(y)
print(y)
eval_loop()
This is the code I came up with. As a start wrote it using the If,else conditionals to understand the flow of code. Then wrote it using the while loop
import math
#using the eval function
"""eval("") takes a string as a variable and evaluates it
Using (If,else) Conditionals"""
def eval_(n):
m=int(n)
print("\nInput n = ",m)
x=eval('\nmath.pow(m,2)')
print("\nEvaluated value is = ", x)
def run():
n= input("\nEnter the value of n = ")
if n=='done' or n=='Done':
print("\nexiting program")
return
else:
eval_(n)
run() # recalling the function to create a loop
run()
Now Performing the same using a While Loop
"using eval("") function using while loop"
def eval_1():
while True:
n=input("\nenter the value of n = ") #takes a str as input
if n=="done" or n=="Done": #using string to break the loop
break
m=int(n) # Since we're using eval to peform a math function.
print("\n\nInput n = ",m)
x=eval('\nmath.pow(m,2)') #Using m to perform the math
print("\nEvaluated value is " ,x)
eval_1()
This method will run the eval on what a user input first, then adds that input to a new variable called b.
When the word "done" is input by the user, then it will print the newly created variable b - exactly as requested by the exercise.
def eval_loop():
while True:
a = input("enter a:\n")
if a == "done":
print(eval(b)) # if "done" is entered, this line will print variable "b" (see comment below)
break
print(eval(a))
b = a # this adds the last evaluated to a new variable "b"
eval_loop()
import math
b = []
def eval_loop():
a = input('Enter something to eval:')
if a != 'done':
print(eval(a))
b.append(eval(a))
eval_loop()
elif a == 'done':
print(*b)
eval_loop()