content = """Name,7/1/2009,7/2/2009,7/3/2009,7/4/2009
Place A,,5,3,
Place B,0,,23,--
Place C,1,2,,35"""
lines = [line.split(',') for line in content.split('\n')]
for line in lines:
    if 'Name' not in line[0]:
        for count, date in enumerate(lines[0]):
            if count >= 1:
                if not line[count] or line[count] == '--':
                    line[count] = 0
print((line[0], date, line[count]))
Реорганизуйте CSV, чтобы даты не были заголовками столбцов