Pfthb

I have a csv file which is not consistent. It looks like this where some have a middle name and some do not. I don't know the best way to fix this. The middle name will always be in the second position if it exists. But if a middle name doesn't exist the last name is in the second position.

john,doe,52,florida

jane,mary,doe,55,texas

fred,johnson,23,maine

wally,mark,david,44,florida

Let's say that you have ① wrong.csv and want to produce ② fixed.csv.

You want to read a line from ①, fix it and write the fixed line to ②, this can be done like this

with open('wrong.csv') as input, open('fixed.csv', 'w') as output:
 for line in input:
 line = fix(line)
 output.write(line)

Now we want to define the fix function...

Each line has either 3 or 4 fields, separated by commas, so what we want to do is splitting the line using the comma as a delimiter, return the unmodified line if the number of fields is 3, otherwise join the field 0 and the field 1 (Python counts from zero...), reassemble the output line and return it to the caller.

def fix(line):

 items = line.split(',') # items is a list of strings

 if len(items) == 3: # the line is OK as it stands
 return line

 # join first and middle name
 first_middle = join(' ')((items[0], items[1]))

 # we want to return a "fixed" line,
 # i.e., a string not a list of strings
 # we have to join the new name with the remaining info
 return ','.join([first_second]+items[2:])