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and. def q(x): if (x>5) and (x < 10): return("just enough") elif (x >= 10) and (x < 15): return("too much") else: return("no idea") print(q(12)) What does and do? What type is returned from this function?. Logical Operators. diff?. def q2(x):

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  1. and def q(x): if (x>5) and (x < 10): return("just enough") elif (x >= 10) and (x < 15): return("too much") else: return("no idea") print(q(12)) • What does and do? • What type is returned from this function?

  2. Logical Operators

  3. diff? def q2(x): if (x>6) or (x < 5): return("just enough") elif (x > 15) or (x < 20): return("too much") else: return("no idea") print(q2(7)) print(q2(13)) def q1(x): if (x>6) and (x < 5): return("just enough") elif (x > 15) and (x < 20): return("too much") else: return("no idea") print(q1(7)) print(q1(13))

  4. What happens? def ReturnSomething(value): if value = 1: return “glub” else: return “blug” print (ReturnSomething(1))

  5. Adding Strings: defaddstrings(par1): return(par1 + "ubba") print (addstrings("gub")) def addmore(par1): return(addstrings(par1)+addstrings(par1)) print(addmore("hab"))

  6. Printing inside my function: • What if I want to see the string that was input into the function? defaddstrings(par1): print(“par1 came in”) return(par1 + "ubba") print (addstrings("gub")) We want to print what’s inside par1, not “par1”

  7. Printing inside my function: • What if I want to see the string that was input into the function? defaddstrings(par1): print(par1 + “came in”) return(par1 + "ubba") print (addstrings("gub")) Now we’re adding what’s inside par1 to “came in” and that is what gets printed by the function before we leave the function.

  8. Printing inside a function deff_to_c(ftemp): print("The temp before conversion is ftemp") return((ftemp - 32 )/ 1.8) print (f_to_c(68)) print (f_to_c(22)) • Is this what we wanted? deff_to_c(ftemp): print("The temp before conversion is” + ftemp) return((ftemp - 32 )/ 1.8) print (f_to_c(68)) print (f_to_c(22))

  9. Solution def f_to_c(ftemp): print("The temp before conversion is” + str(ftemp)) return((ftemp - 32 )/ 1.8) print (f_to_c(68)) print (f_to_c(22)) • Note: • ftemp is not in quotes. • When it is not in quotes, we’re talking about what’s inside of ftemp and not the word ftemp • what is inside of ftemp is an integer. • We can’t add integers to strings • str(ftemp) • takes the number inside of the parameter ftemp and converts it to a string

  10. Input function • NOT the same as an input parameter!!!! def f(x): return(x + input(“What do you want to say?”)) f(“You said ”) • What type does the input function return? def f(x): return(x + input(“What do you want to add?”)) f(3) • Instead: def f(x): return(x + int( input(“What do you want to add?”))) f(3)

  11. defgetverb(x): if x == 17: return("am") elif x == 24: return("was") elif x == 32: return("love") else: return("ran over") print(getverb(27)) defmakeit(x,y,z): return(getname(z) + getpron(y) + getverb(x)) print(makeit(17,3,7)) defgetname(x): if x == 3: return("John") elif x == 13: return("Joe") elif x == 7: return("Sam") else: return("Bob") print(getname(13)) defgetpron(x): if x == 2: return("you") elif x == 3: return("I") elif x == 4: return("she") elif x == 5: return("he") else: return("it") print(getpron(5))

  12. New Function • input : 3 integers - x, y and z • Output: a string • “Yes x is divisible by both y and z” or • “No, x is not evenly divisible by y and z” • “x is not in range” • Function name: isDivisible • Calculations: • Two parts: • check if x is between 0 and 100 • Check if x is evenly divisible by both y and z

  13. #input : 3 integers, x, y and z #Output: a string # “Yes x is divisible by both y and z” or # “No, x is not evenly divisible by y and z” # “x is not in range” #Function name: isDivisible #Calculations: check if x is greater than 0 and less than 100 and is evenly #divisible by both y and z def isDivisible(x, y,z): if ((x > 0)and (x < 100)) and ((x%y) == 0) and (x % z) == 0): #ugh! Long and hard to read return (“Yes “+str(x)+” is divisible by both “+str(y)+” and “+str(z)) else: return (“No, “+str(x)+” is not evenly divisible by “+str(y)+” and “+str(z)) print(isDivisible(15,5,3)) print(isDivisible(150,5,3)) Is this what we want ? Will it always work?

  14. #input : 3 integers, x, y and z #Output: a string # “Yes x is divisible by both y and z” or # “No, x is not evenly divisible by y and z” # “x is not in range” #Function name: isDivisible #Calculations: check if x is greater than 0 and less than 100 and is evenly #divisible by both y and z def isDivisible(x, y,z): if ((x > 0)and (x < 100)) and ((x%y) == 0) and (x % z) == 0): return (“Yes “+str(x)+” is divisible by both “+str(y)+” and “+str(z)) elif((x > 0)and (x < 100)) : return (“No, “+str(x)+” is not evenly divisible by “+str(y)+” and “+str(z)) else: return (str(x) + “is not in range”) print(isDivisible(15,5,3)) print(isDivisible(150,5,3)) Is this what we want ? Will it always work?

  15. #input : 3 integers, x, y and z #Output: a string # “Yes x is divisible by both y and z” or # “No, x is not evenly divisible by y and z” # “x is not in range” #Function name: isDivisible #Calculations: check if x is greater than 0 and less than 100 and is evenly #divisible by both y and z def isDivisible(x, y,z) if (x > 0)and (x < 100): if ((x%y) == 0) and ((x % z) == 0): return (“Yes “+str(x)+” is divisible by both “+str(y)+” and “+str(z)) else: return (“No, “+str(x)+” isn’t evenly divisible by “+str(y)+” and “+str(z)) else: return(str(x ) + “ is not in range”) print(isDivisible(15,5,3)) print(isDivisible(150,5,3)) Now what if x is 250 or -1?

  16. Same? def g(x): if (x > 5): if (x < 10): return("just enough") elif (x < 15): return("too much") else: return("no idea") def g(x): if (x>5) and (x < 10): return("just enough") elif (x > 5) and (x < 15): return("too much") else: return("no idea") print (g(12)) What about: print (g(17))

  17. Loan Qualifier We want to write a function that tells someone whether they qualify for a loan. • If a person makes more than 35,000 and they’ve been employed for at least 2 years, • they qualify. • If they make over 35,000, but haven’t been employed for at least 2 years, • They should get a message saying how long they need to wait before they can get the loan • (e.g., if they’ve only been employed for 1.2 years, the program should tell them to come back in .8 years) • If they don’t make 35,000, but have been employed for over 2 years, • They should get a message telling them the minimum salary requirement • If they don’t make 35,000 and they haven’t been employed for 2 years, • they don’t qualify. Using Nested If (ifs inside of ifs) can you write this?

  18. LoanQualifier def loanqualifier(sal,yrs): if (sal > 35000): if (yrs >= 2): return("Congratulations! You qualify!") else: return("You will qualify in " + str(round(2-yrs) ,2)+ " years.") else: if (yrs>=2): return("You need to make at least 35000 to qualify for a loan") else: return("I'm sorry, you don't qualify.") #Note the test cases – we’re testing all outputs to make sure they work print (loanqualifier(40000,4)) print (loanqualifier(40000,1.2)) print (loanqualifier(20000,4)) print (loanqualifier(20000,1.2))

  19. Quick function: • Write a function that checks to see if a number is even or odd. • What TYPE does this return?

  20. def ismultof3(x): if ((x%3) == 0): return(True) else: return(False) When python executes the following statement, what is the result? (x%3)==0 def ismultof3(x): return((x%3) == 0) def func2(x): if (ismultof3(x)): # Can we see why specifying what type # is returned from a function is critical?!? return(str(x) + " is a multiple of 3") else: return(str(x) + " is not a multiple of 3")

  21. Returning to Boolean Values: • Quadratic Equation: • x2 -3x – 4 = 0 • Is this true for 1? 2? 3? 4? • Can you write a function that returns the answer to this question? • Hint: the function needs to return a boolean value. • What is the input? • How do you check for the output?

  22. Function to represent this: #Name: eqcheck #Calculation: Determines if input value (x) will solve #the problem: # x2 -3x – 4 = 0 #Input: x: a number #Output: a boolean value def eqcheck(x): return (x**2 –3*x – 4) == 0 What is returned? print(eqcheck(3)) What is returned? print(eqcheck(4))

  23. Remember? defSqur(par1): return(par1 ** 2) defdbl(par2): return(par2 + par2) def Func4(p1,p2): return(dbl(Squr(p2)+ Squr(p2)+3)) print(Func4(2,4)) def Func5(p1): return(dbl(dbl(dbl(p1)))) print(Func5(4))

  24. What gets printed out? def f(n): if (n == 0): return (" ") else: print(“blug ") return f(n-1) f(3)

  25. What about? deff(x): if (x == 0): return x else: return(x + f(x-1)) print(f(4)) deff2(x): if (x == 1): return (str(x)) else: return(str(x) + f2(x-1)) print(f2(4))

  26. Recursion • Recursion is when a function is defined in terms of itself (it calls itself). • Def: A recursivedefinitionis one that defines something in terms of itself (that is, recursively) • Recursion is, in essence, making a function happen again and again without our having to call it (convenient, huh?) #This is recursion def recurse(): return(recurse()) #This isn’t def nonrecurse(): return(“nope”)

  27. Try: def f3(x): if (x == 1): return x else: return(x + f3(x-2)) print(f3(4,0)) def f(x): return(x + f(x-1)) print(f(4)) def f2(x): if (x == 1): return x else: return(x + f2(x+1)) print(f2(4))

  28. How about: def f(x): if x == 100: return(“none") else: if (x**2 - 3 *x - 4) == 0: print(str(x) + " solves the equation ") return(f(x+1)) print(f(-100))

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