Iterate through dictionary values

Question

Hey everyone I m trying to write a program in Python that acts as a quiz game  I made a dictionary at the beginning of the program that contains the values the user will be quizzed on  Its set up like so   PIX0     QVGA   320x240    VGA   640x480    SVGA   800x600     So I defined a function that uses a for loop to iterate through the dictionary keys and asks for input from the user  and compares the user input to the value matched with the key   for key in PIX0      NUM   input  What is the Resolution of  s      key      if NUM    PIX0 key           print   Nice Job            count   count   1     else          print  I m sorry but thats wrong  The correct answer was   s     PIX0 key      This is working fine output looks like this   What is the Resolution of Full HD  1920x1080 Nice Job  What is the Resolution of VGA  640x480 Nice Job    So what I would like to be able to do is have a separate function that asks the question the other way  providing the user with the resolution numbers and having the user enter the name of the display standard  So I want to make a for loop but I don t really know how to  or if you even can  iterate over the values in the dictionary and ask the user to input the keys   I d like to have output that looks something like this   Which standard has a resolution of 1920x1080  Full HD Nice Job  What standard has a resolution of 640x480  VGA Nice Job    I ve tried playing with for value in PIX0 values   and thats allowed me to iterate through the dictionary values  but I don t know how to use that to  check  the user answers against the dictionary keys  If anyone could help it would be appreciated   EDIT  Sorry I m using Python3

User · Answer

You can just look for the value that corresponds with the key and then check if the input is equal to the key.

for key in PIX0:
    NUM = input("Which standard has a resolution of %s " % PIX0[key])
    if NUM == key:

Also, you will have to change the last line to fit in, so it will print the key instead of the value if you get the wrong answer.

print("I'm sorry but thats wrong. The correct answer was: %s." % key )

Also, I would recommend using str.format for string formatting instead of the % syntax.

Your full code should look like this (after adding in string formatting)

PIX0 = {"QVGA":"320x240", "VGA":"640x480", "SVGA":"800x600"}

for key in PIX0:
    NUM = input("Which standard has a resolution of {}".format(PIX0[key]))
    if NUM == key:
        print ("Nice Job!")
        count = count + 1
    else:
        print("I'm sorry but that's wrong. The correct answer was: {}.".format(key))

User · Answer

Depending on your version   Python 2 x   for key  val in PIX0 iteritems        NUM   input  Which standard has a resolution of   r    format val       if NUM    key          print   Nice Job            count   count   1     else          print  I m sorry but thats wrong  The correct answer was    r    format key     Python 3 x   for key  val in PIX0 items        NUM   input  Which standard has a resolution of   r    format val       if NUM    key          print   Nice Job            count   count   1     else          print  I m sorry but thats wrong  The correct answer was    r    format key     You should also get in the habit of using the new string formatting syntax     instead of   operator  from PEP 3101   https   www python org dev peps pep-3101

User · Answer

If all your values are unique  you can make a reverse dictionary   PIXO reverse    v  k for k  v in PIX0 items      Result    gt  gt  gt  PIXO reverse    320x240    QVGA    640x480    VGA    800x600    SVGA     Now you can use the same logic as before

User · Answer

You could search for the corresponding key or you could  invert  the dictionary  but considering how you use it  it would be best if you just iterated over key value pairs in the first place  which you can do with items    Then you have both directly in variables and don t need a lookup at all   for key  value in PIX0 items        NUM   input  What is the Resolution of  s      key      if NUM    value    You can of course use that both ways then   Or if you don t actually need the dictionary for something else  you could ditch the dictionary and have an ordinary list of pairs

User · Answer

Create the opposite dictionary   PIX1      for key in PIX0 keys        PIX1 PIX0 get key     key   Then run the same code on this dictionary instead  using PIX1 instead of PIX0    BTW  I m not sure about Python 3  but in Python 2 you need to use raw input instead of input

[python] Iterate through dictionary values?

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