Comparing in lists in Python

Question

So for my program I have two definitions, get_codes and get_data, that I created 8 total lists from, shown below:

CountryCodes=open("CountryCodes.csv",'r')
CountryData=open("CountryData.csv", 'r')

def get_codes(file):
    country_code=[]
    country_name=[]
    continent=[]

    for line in CountryCodes: 
        c_fields=line.split(",")

        c_field1=c_fields[0].strip()
        c_field2=c_fields[1].strip()
        c_field3=c_fields[2].strip() 

        country_code.append(c_field1)
        country_name.append(c_field2)
        continent.append(c_field3)

    return country_code, country_name, continent

def get_data(file): 
    data_country_code=[]
    country_pop=[]
    country_area=[]
    country_gdp=[]
    country_lit_rate=[]

    for line in CountryData: 
        d_fields=line.split(",")

        d_field1=d_fields[0].strip()
        d_field2=d_fields[1].strip()
        d_field3=d_fields[2].strip()
        d_field4=d_fields[3].strip()
        d_field5=d_fields[4].strip()

        data_country_code.append(d_field1)
        country_pop.append(int(d_field2))
        country_area.append(d_field3)
        country_gdp.append(int(d_field4))
        country_lit_rate.append(d_field5)

    return data_country_code, country_pop, country_area, country_gdp, country_lit_rate

Now what I have to do is create a menu option (I have the menu) that gives the country_pop in ascending, and later descending, order. Here's what I have so far:

def asc_sort():
    for x in range (0,len(country_pop)):
        country_pop2=sorted(country_pop)

I have the sorting down, but my professor doesn't only want the country_pop2 printed. She also wants the country_name, which is in CountryCodes, not CountryData where the population is. So the country_pop's index, x, should also be x in data_country_code. I then need to take the input of x in data_country_code, let's say it's AL, and find that in country_code. Next I'll have to find the corresponding country_name, Albania, to the country_code, AL and list the country_name with the country_pop which I assume would be something like:

print("%-10s \t %-10s \t" %("NAMES","POPULATION"))
for ind in range (0,len(list1)):
    if ind%10==9:
        input("Press ENTER to continue")
    print("%-2s \t %-10s \t %-10s \t %-10s \t %-10s \t" %(I'd need help here)

(I need the %-10s part for formatting and the if statement because my list is so long I only want a few to show at a time) Any help would be appreciated, and if anyone needs more explaining I'll do my best!

Answer 1

I think the following code does what you want:

with open("CountryCodes.csv",'r') as CountryCodes:
    genc = (line.split(',') for line in CountryCodes)

    c2n = dict((c_fields[0].strip(),c_fields[1].strip())
               for c_fields in genc)

with open("CountryData.csv",'r') as CountryData:
    gend = (line.split(',') for line in CountryData)

    the_data = [ (c2n[d_fields[0].strip()], # data_country_code
                  int(d_fields[1]),         # country_pop
                  d_fields[2].strip(),      # country_area
                  d_fields[3].strip(),      # country_gdp
                  d_fields[4].strip())      # country_lit_rate
                 for d_fields in gend ]

the_data.sort(key = lambda x: x[1])

p = 10
for i in xrange(0,len(the_data),p):
    if i:  raw_input("  Press ENTER to continue\n")
    print ('\n'.join("%-10s \t %-10s \t %-10s \t %-10s \t %s"
                     % el for el in the_data[i:i+p]) )

The dictionary c2n gives the names corresponding to codes.

The population field is certainly a string expressing an integer that doesn't need to be striped, even if there are whitespaces in it (blanks, tabs... not newlines)

.

EDIT

If you're not authorized to use a dictionary but only lists, you cab do like that:

with open("CountryCodes.csv",'r') as CountryCodes:
    genc = (line.split(',') for line in CountryCodes)
    lic = [map(str.strip,row) for row in genc]

def name_of(x,lic=lic):
  for code,name,continent in lic:
    if x==code:
      return name

with open("CountryData.csv",'r') as CountryData:
    gend = (line.split(',') for line in CountryData)

    the_data = [ (name_of(d_fields[0].strip()), # data_country_code
                  int(d_fields[1]),         # country_pop
                  d_fields[2].strip(),      # country_area
                  d_fields[3].strip(),      # country_gdp
                  d_fields[4].strip())      # country_lit_rate
                 for d_fields in gend ]

Answer 2

you need to do two things:

1. store all the data in a line from CountryData in a tuple, rather than separate lists. that way, when you rearrange everything in your sort, you also rearrange the county codes.

2. store the data from CountryCodes in a dict, so that you can go from code to country name.

i'm not sure i should be doing all your homework for you, but if you have data like this:

country_data = [('uk', 123), ('usa', 42), ('cl', 99)]
country_names = {'uk': 'united kingdom', 'usa': 'united states', 'cl': 'chile'}

then this would give you the country names ordered by the numbers:

sorted_data = sorted(country_data, key=lambda data: data[1])
for (code, value) in sorted_data:
    print(country_names[code], value)

note how the key picks out the second element of the tuple to sort. so, for ('uk', 123) it will give 123, which is what you want to sort by.