PYTHON 读写CSV

import csv
data=[]
file1=open("xx2.csv",mode="w")
writer=csv.writer(file1)
with open("sc.csv",'r',encoding='utf-8') as file:
    reader=csv.DictReader(file)
    ab=0
    for row in reader:
        data=[]
        ab=ab+1

        data.append(ab)
        data.append(row["v1"])
        data.append(row["v2"])
        data.append(row["v3"])
        data.append(row["v4"])
        data.append(row["v5"])
        data.append(row["v6"])
        data.append(row["v7"])
        data.append(row["v8"])
        data.append(row["v9"])
        data.append(row["v10"])
        data.append(row["v11"])
        data.append(row["v12"])
        data.append(row["v13"])
        data.append(row["v14"])
        data.append(row["v15"])
        data.append(row["v16"])
        data.append(row["v17"])
        data.append(row["v18"])
        data.append(row["v19"])
        data.append(row["v20"])
        data.append(row["v21"])
        data.append(row["v22"])
        data.append(row["v23"])
        data.append(row["v24"])
        data.append(row["v25"])
        print(row["v1"],row["v2"],row["v3"])
        if ab>50:
            break
            pass
        writer.writerow(data)
file1.close()