Develop Reference

Entering Values, and adding specific types

Trying to figure out how to work a list of user input integers into separate categories and adding those categories together, and I'm stuck. This is what I have so far:
def main():
again = 'y'
while again == 'y':
pos_values = []
neg_values = []
value = int(input("Please enter value: "))
if value > 0:
pos_values.append(value)
print('Would you like to add another value?')
again = input('y = yes; n = no: ')
elif value < 0:
neg_values.append(value)
print('Would you like to add another value?')
again = input('y = yes; n = no: ')
else:
print(sum.pos_values)
print(sum.neg_values)
print('Would you like to add another value?')
again = input('y = yes; n = no: ')
total = 0
all_values = neg_values + pos_values
print[all_values]
print(total + pos_values)
print(total + neg_values)
main()
I'm just a first year student with no prior experience, so please be gentle!

Once you fix the logic error pointed out by Mike Scotty, the other problems are really just syntax errors. sum.pos_values will give you AttributeError: 'builtin_function_or_method' object has no attribute 'pos_values' (because sum is a built-in function and so needs () not .); and print[all_values] will give you a syntax error (because print is also a built-in function and so needs () not []). Your original code doesn't store zeroes in either list: I haven't changed that. And the output format is a guess on my part.
def main():
again = 'y'
pos_values = []
neg_values = []
while again == 'y':
value = int(input("Please enter value: "))
if value > 0:
pos_values.append(value)
elif value < 0:
neg_values.append(value)
else: #edit: terminate also on 0 input
break
print('Would you like to add another value?')
again = input('y = yes; n = no: ')
all_values = neg_values + pos_values
print(sum(all_values),all_values)
print(sum(pos_values),pos_values)
print(sum(neg_values),neg_values)

How do I display the max function i created in python

I have to get userinputs of ints and store them in a array, and print the max number in the list. But I had to create my own max function. Im not sure what steps to take to implement it into my code.
def getInt(prompt):
n = int
done = False
while not done:
try:
n = int(input(prompt))
except ValueError:
print("I was expecting a number, please try again...")
if n == 0:
done = True
return n
def maxNum(l):
maxi = [0]
for num in l:
if maxi > num:
maxi = num
return maxi
def result():
print("The maxium value is: " + maxNum(i))
def main():
num = []
i = 0
done = False
while not done:
num = getInt("Please enter an integer < 0 to finish >: ")
if num == 0:
done = True
results = maxNum(i)

The below code does exactly what you want.
def getInt(prompt):
try:
n = int(input(prompt))
return n
except ValueError:
print("I was expecting a number, please try again...")
getInt()
def maxNum(lst):
if not lst: # if list is empty
return None
max_elem = lst[0]
for x in lst:
if x > max_elem:
max_elem = x
return max_elem
def main():
nums = []
while True:
num = getInt("Please enter an integer < 0 to finish >: ")
if num == 0:
break
nums.append(num)
result = maxNum(nums)
print("The maxium value is: " + str(result))
main()

python support built-in max function
max([1,2,3]) # return 3
and Your code is totally wrong.
if you want to input array of integers, getInt may be like this.
def getInt():
array = []
while True:
x = int(input('message'))
if x == 0: break
array.append(x)
return array
and main code will be
array = getInt()
max_value = max(array)
print (max_value)
if you want your own max function, it can be
def max_func(array):
max_val = array[0]
for val in array:
if val > max_val: max_val = val
return max_val

Here is a fixed version of your maxNum function:
def maxNum(l):
if not l:
return None # or return whatever you want if user did not input anything
maxi = l[0] # it expects 'l' to be an array!
for num in l[1:]:
if maxi > num:
maxi = num
return maxi
Let's also fix your getInt function:
def getInt(prompt):
while True:
try:
return int(input(prompt))
except ValueError:
print("I was expecting a number, please try again...")
Finally, your "main" function needs the following fix:
def main():
num = []
n = 1
while n != 0:
n = getInt("Please enter an integer < 0 to finish >: ") # store user input into n - do not overwrite num!
num.append(n) # append each user value to the list num
results = maxNum(num) # pass the entire *list* to maxNum

None output when I run my code

I run this code:
def fact(i):
j = 1
while i >= 1:
j = i * j
i -= 1
i = input("input the number: ")
print (fact(i))
and see this output:
input the number: 6
None
Why is my output None? What is wrong?

You are printing the result of a function. In order for a function to return result, you must use the return statement. If you don't return anything, then the the function will automaticaly return None. I suspect you want your function to return j so you need to add return j to the end of the function for it to work.
That should work:
def fact(i):
j = 1
while i >= 1:
j = i * j
i -= 1
return j
i = input("input the number: ")
print (fact(i))

Function based on conditions will not return value- python

I am new to this, and I am looking for help. I currently am stuck in a program I'm trying to complete. Here it is:
def searchStock(stockList, stockPrice, s):
for i in range(len(stockList)):
if s == stockList[i]:
s = stockPrice[i]
elif s != stockList[i]:
s = -1
return s
def mainFun():
stockList= []
stockPrice = []
l = 1
while l > 0:
stocks = str(input("Enter the name of the stock:"))
stockList += [stocks]
if stocks == "done"or stocks == 'done':
l = l * -1
stockList.remove("done")
else:
price = int(input("Enter the price of the stock:"))
stockPrice += [price]
l = l + 1
print(stockList)
print(stockPrice)
s = input("Enter the name of the stock you're looking for:")
s = searchStock(stockList, stockPrice, s)
Every time I run the program to the end, it never returns the variable s for some reason. If i replace return with print, it always prints -1 instead of the stockPrice if its on the list. I cant seem to get it to work. Can someone please help me?

Try adding this print to help you debug:
def searchStock(stockList, stockPrice, s):
output = -1
for i in range(len(stockList)):
if s == stockList[i]:
output = stockPrice[i]
print i, output, stockList[i], stockPrice[i]
elif s != stockList[i]:
output = -1
return output
Also I changed one of your variables, it seems better than modifying your input value and then returning it.

python: program hanging! (print issue maybe?)

So, I'm quite nooby at python. I decided to make a program that makes prime numbers. I know there's probably a function built in that does this but I decided to do it myself.
number = 1
numlist = list()
for x in range (0, 1000):
numlist.append("")
print "Created list entry " + str(x)
while True:
number = number + 1
if number % 2 != 0:
numscrollerA = 1
numscrollerB = 1
while numscrollerA <= number:
if float(number) / float(numscrollerA) == float(int(number)):
numlist[numscrollerA] = "true"
if float(number) / float(numscrollerA) != float(int(number)):
numlist[numscrollerA] = "false"
numscrollerA = numscrollerA + 1
while numscrollerB <= number:
if numscrollerB != 1 and numscroller != number and numlist[numscrollerB] == "true":
primestatus = "false"
else:
primestatus = "true"
if primestatus == "true":
print number
I get "Created list entry x" 1000 times as I should. Then the program just hangs.

while numscrollerB <= number:
if numscrollerB != 1 and numscroller != number and numlist[numscrollerB] == "true":
primestatus = "false"
else:
primestatus = "true"
You don't increase numscrollerB in this loop, so it runs infinitedly. Anyway, You should rather use 'for loop':
for numscrollerB in range(1, number+1):
pass # do something

Your code is very unpythonic. Typical of a newcomer experienced in a different style of coding.
Your list is uneccessary.
In python you could create the list like this
def check_even(val):
#this contains your logic
return val % 2 == 0
evenslist = [check_even(i) for i in xrange(1, 1001)]
print numlist