python不知道怎么了

Question

I want write a function to achieve open a file->choose a certain column->take out the non repeated names->write the names into another file. I have written some code like this:

def method2(filename):
    name = filename + '.txt'
    content = open(name,'r')

    for line in content:
        values = line.split()
        a = values[1]

        print(a)

the error is:

>>> method2('test')
d8:c7:c8:5e:7c:2d,
Traceback (most recent call last):
  File "<pyshell#12>", line 1, in <module>
    method2('test')
  File "C:/Users/Yifan/Desktop/data/Training data/Method2.py", line 10, in method2
    a = values[1]
IndexError: list index out of range

my file looks like this:

  1405684432,        d8:c7:c8:5e:7d:e8,          SUTD_Guest,   57



  1405684432,        d8:c7:c8:5e:7c:89,           SUTD_ILP2,   74



  1405684432,        d8:c7:c8:5e:7c:8d,           SUTD_GLAB,   74



  1405684432,        b0:c5:54:dc:dc:6c,              ai-ap1,   85

Answer 1

When you reach the second line, which looks empty, and split it, you only get an empty list in values . Trying to access element 1 , ie the second, fails, because there is no second element.

Try putting if len(values) > 0: in there to protect a = line[1] .

Answer 2

Here you go

test.py

def read_file(filename):
    file = open(filename)
    contents = map(str.strip,file.readlines())
    file.close()
    return contents

def get_column_values(col_num,lines):
    column_values = []

    for line in lines:
        if not line:
            continue

        values = line.split()

        #col_num - 1 = index of list
        #[:-1] will chop the last char i.e. comma from the string
        column_values.append(values[col_num-1][:-1])

    return column_values

def remove_duplicates(xList):
    return list(set(xList))


def write_file(filename,lines):
    file = open(filename,"w")
    for line in lines:
        file.write("%s\n" % line)
    file.close()


def main():
    lines = read_file("input.txt")

    #Work on 1st Column i.e. 0th index
    column_values = get_column_values(1,lines)
    entries = remove_duplicates(column_values)
    write_file("output.txt",entries)

main()

input.txt

1405684432,        d8:c7:c8:5e:7d:e8,          SUTD_Guest,   57

1405684432,        d8:c7:c8:5e:7c:89,           SUTD_ILP2,   74

1405684432,        d8:c7:c8:5e:7c:8d,           SUTD_GLAB,   74

1405684432,        b0:c5:54:dc:dc:6c,              ai-ap1,   85

output.txt 1405684432