How format my data in category in python

Question

a python program to read the rainfall.txt file and then write out a new file called rainfallfmt.txt . The data should be grouped on the total annual rainfall field into the following categories: [60-70], [71-80], [81-90],[91-]. Under each category, the new file should format each line so that the city is right-justified in a field that is 25 characters wide, and the rainfall data should be printed in a field that is 5 characters wide with 1 digit to the right of the decimal point. This is what I have so far; the problem is I don't know how to categorize it? Would you please help me and let me know how I can solve this problem?

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 # read the rainfall.txt then write out a new file called rainfall.txt
    # the data should be grouped on the total annual rainfall field into the 
    # categories: [60-70], [71-80], [81,90], [91-]

        import os.path

        def main():
            endofprogram = False
            try:
                InputFileName = input('Enter name of input file: ')
                infile = open(InputFileName,'r')
                OutputFileName = input('Enter name of output file: ')
                # determine wether name exists
                while True:
                    if os.path.isfile(OutputFileName):
                        OutputFileName = input('File Exists. Enter name again: ')
                    else:
                        outfile = open(OutputFileName,'w')
                        break
            except IOError:
                print("Error opening file - End of program")
                endofprogram = True

                #If there is not exception, start reading the input file
                #Write the same data in formated form in new file.
                if endofprogram == False:
                    data = []
                    for line in infile:
                    .
                    .# I dont know what to do in here!
                    .
                    outfile.write(data[0])
        main()

Answer 1

You can use split to separate the line in fields (it returns a list of strings), then take the rainfall, convert it to float, and use a list per category to store the data.

cat_60 = []
cat_71 = []
cat_81 = []
cat_91 = []
for line in infile:
    city, rain = line.split(' ')    # Spliting using blank as separator
    rain = float(rain)

    if 60 <= rain <= 70:            # This works in Python as expected but don't in most other languages
        cat_60.append((city, rain)) # Storing a tuple at the end of the list
    elif 71 <= rain <= 80:
        cat_71.append((city, rain))
    # etc...

After that you can iterate in the categories and format the output with str.format() or using the % operator.

There are other things you can do to make your code more Pythonic, for example variable names should be snakecase, names in titlecase should be reserved for classes and uppercase for constants and instead of using a flag variable you can use and exit() to end the program.

You can do the following to call main() only if the file is invoked as a script:

if __name__ == '__main__':
    main()

Answer 2

# read the rainfall.txt then write out a new file called rainfall.txt
# the data should be grouped on the total annual rainfall field into the 
# categories: [60-70], [71-80], [81,90], [91-]
import os.path

def main():

    endofprogram = False
    try:
        InputFileName = input('Enter name of input file: ')
        infile = open(InputFileName,'r')
        OutputFileName = input('Enter name of output file: ')
        # determine wether name exists
        while True:
            if os.path.isfile(OutputFileName):
                OutputFileName = input('File Exists. Enter name again: ')
            else:
                outfile = open(OutputFileName,'w')
                break
    except IOError:
        print("Error opening file - End of program")
        endofprogram = True

        #If there is not exception, start reading the input file
        #Write the same data in formated form in new file.
    if endofprogram == False:
        cat_60 = []
        cat_71 = []
        cat_81 = []
        cat_91 = []
        for line in infile:
            city, rain = line.split(' ')
            rain = float(rain)

            if 60 <= rain < 70:            
                cat_60.append((city, rain)) # Storing a tuple in the list
            elif 70 <= rain < 80:
                cat_71.append((city, rain))  
            elif 80 <= rain < 90:
                cat_81.append((city, rain))
            elif 90 <= rain :
                cat_91.append((city, rain))

        outfile.write("[60-70]"+'\n')
        for i in range(len(cat_60)):
            city = cat_60[i][0]
            rain = cat_60[i][1]
            outfile.write('%+25s'%(city)+'%5.1f'%(rain)+'\n')

        outfile.write("[70-80]"+'\n')
        for i in range(len(cat_71)):
            city = cat_71[i][0]
            rain = cat_71[i][1]                
            outfile.write('%+25s'%(city)+'%5.1f'%(rain)+'\n')

        outfile.write("[80-90]"+'\n')
        for i in range(len(cat_81)):
            city = cat_81[i][0]
            rain = cat_81[i][1]
            outfile.write('%+25s'%(city)+'%5.1f'%(rain)+'\n')

        outfile.write("[91-]"+'\n')
        for i in range(len(cat_91)):
            city = cat_91[i][0]
            rain = cat_91[i][1]
            outfile.write('%+25s'%(city)+'%5.1f'%(rain)+'\n')
main()