Python 2.0.7，将一些值逐行写入csv文件

Question

I have a lot of lists, each with twelve values:

["0.0051", "-0.0351", ..., "0.0325"]
["0.0065", "0.0014", ..., "0.0851"] . . . ["0.0151", "0.0512", ... , "0.00917"]

Each list has a id number that is like 2, 4, 7, 9...

I want to write this list to a csv file row by row (if we see csv file by excel each row has 12 values and each row indicate the id_number)

I just coded it like

if existed_id != cur_id:
       cur_ id = existed_id
       value_list.append("/n")
       with open ('outcome.csv', 'w') as csvfile:
                 g = csv.writer(csvfile, delimiter = ',')
                 data = value_list
                 g.writerow(data)

When run, it is not fully written in my csv file. What's going wrong?

Answer 1

If your records are a list of lists od strings:

records = [["0.0051", "-0.0351", ..., "0.0325"],
           ["0.0065", "0.0014", ..., "0.0851"],
            . . .
           ["0.0151", "0.0512", ... , "0.00917"]`

then the following code will write a csv file with len(records) lines:

with open('outcome.csv', 'w') as csvfile:
    g = csv.writer(csvfile, delimiter=',')
    for record in records:
         g.writerow(data)

The with open... line creates a new file (and overwrites a possibly previously existing file), so be sure you do not put it into a loop over records, because at the end only the last record would be saved into the file.