code for the example in the Note on Hashing

Simple Hash<strong>in</strong>g Algorithm
snIn = open ("names.txt","r") # Opens a path to <strong>the</strong> data file
collision = 0 # Stores <strong>the</strong> number of collisions
listOfStudents = [] # List to store data
# Section to load an "empty" list with bogus data
<strong>for</strong> i <strong>in</strong> range (0,10):
listOfStudents.append ("zzz")
pr<strong>in</strong>t (listOfStudents) # Inserted <strong>for</strong> test<strong>in</strong>g purposes - this l<strong>in</strong>e will be removed
pr<strong>in</strong>t (len (listOfStudents)) # Inserted <strong>for</strong> test<strong>in</strong>g purposes - this l<strong>in</strong>e will be removed
# Section to store <strong>the</strong> names <strong>in</strong> <strong>the</strong> list
while True :
name = str.strip (snIn.readl<strong>in</strong>e ()) # Inputs <strong>the</strong> last name of <strong>the</strong> student from <strong>the</strong> file
if name == "" : # This will exit <strong>the</strong> loop if last name is a null str<strong>in</strong>g (end of file)
break
elementInList = ord (name [0] ) % 10 # Simple hash<strong>in</strong>g algorithm to calculate where <strong>the</strong> name should go
pr<strong>in</strong>t ("Where it should go:", elementInList) # For test<strong>in</strong>g purposes - this l<strong>in</strong>e will be removed
while True: # Will loop until <strong>the</strong> <strong>in</strong>putted name is <strong>in</strong>serted <strong>in</strong> <strong>the</strong> list
if listOfStudents[elementInList] == "zzz": # Inserts name if <strong>the</strong> element is "blank"
listOfStudents[elementInList] = name
pr<strong>in</strong>t ("where it went:", elementInList) # For test<strong>in</strong>g purposes - this l<strong>in</strong>e will be removed
pr<strong>in</strong>t ()
break
else : # If <strong>the</strong> element checked above conta<strong>in</strong>s a name, it will <strong>in</strong>crease <strong>the</strong> element to # be checked by 1
collision +=1
elementInList += 1
if elementInList == len (listOfStudents) : # If <strong>the</strong> end of <strong>the</strong> list is reached, it will start <strong>the</strong> search
# at <strong>the</strong> beg<strong>in</strong>n<strong>in</strong>g of <strong>the</strong> list
elementInList = 0
pr<strong>in</strong>t ("Collisions:", collision) # Inserted <strong>for</strong> test<strong>in</strong>g purposes - this l<strong>in</strong>e will be removed
pr<strong>in</strong>t (listOfStudents) # Inserted <strong>for</strong> test<strong>in</strong>g purposes - this l<strong>in</strong>e will be removed
# Section to f<strong>in</strong>d <strong>the</strong> names <strong>in</strong> <strong>the</strong> list
while True:
nameToF<strong>in</strong>d = <strong>in</strong>put ("What name do you wish to f<strong>in</strong>d: ") # Name user wishes to f<strong>in</strong>d
elementInList = ord (nameToF<strong>in</strong>d[0] ) % 10 # Hash<strong>in</strong>g algorithm to calculate where <strong>the</strong> name should be
while True:
if listOfStudents[elementInList] == nameToF<strong>in</strong>d: # Checks if <strong>the</strong> name is <strong>in</strong> <strong>the</strong> specified element
pr<strong>in</strong>t (name, "is <strong>in</strong> position", elementInList)
pr<strong>in</strong>t ()
break
elif listOfStudents [elementInList] == "zzz": # Outputs a message if <strong>the</strong> name is not found.
pr<strong>in</strong>t (name, "is not found") # This is assumed if <strong>the</strong> element conta<strong>in</strong>s "blank" data
break

else: # If <strong>the</strong> element checked above conta<strong>in</strong>s a name, it will <strong>in</strong>crease <strong>the</strong> element
# to be checked by 1
collision+=1
elementInList += 1
if elementInList == len (listOfStudents) : # If <strong>the</strong> end of <strong>the</strong> list is reached, it will start <strong>the</strong> search
# at <strong>the</strong> beg<strong>in</strong>n<strong>in</strong>g of <strong>the</strong> list
elementInList = 0
aga<strong>in</strong> = <strong>in</strong>put ("Ano<strong>the</strong>r? Y or N ")
if aga<strong>in</strong> == "N":
break