python - 从CSV文件获取值列表

我得到了一个带有订单清单的csv文件，看起来像这样：

CUSTOMER_CODE,CUSTOMER_NAME,NAME,PRODUCT
1044, C1, Name1, Arduino,
1044, C1, Name1, ESP8266,
1048, C2, Name1, Arduino Uno,
1042, C3, Name1, ESP32,
1049, C4, Name1, Arduino Mega,
1042, C3, Name1, Nexus 4,

现在我只想提取客户代码列表
[1042, 1044 ,1048 ,1049]

不

[1042, 1044 ,1044,1044,1044,1044,1044,1044,1048,1048,1048,1048,1048,1048,1048,1049 etc.]

#!/usr/bin/python
import MySQLdb, csv
CUSTOMER_CODES = []

with open('Customers.csv','r') as csvfile:
    reader = csv.DictReader(csvfile)

    for row in reader:
        if len(CUSTOMER_CODES) == 0:
            #adding 1st value
            CUSTOMER_CODES.append(int(row['CUSTOMER_CODE']))
        for i in range(0,len(CUSTOMER_CODES)):
            #check each value of table
            print CUSTOMER_CODES
            if CUSTOMER_CODES[i] == int(row['CUSTOMER_CODE']):
                print "Code is already here "+ str(row['CUSTOMER_CODE'])
            else:
                CUSTOMER_CODES.append(int(row['CUSTOMER_CODE']))

而不是像这样的输出：

[1044, 1045, 1047....]

我有这个：

[1044, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1045, 1047, 1047, 1047, 1047, 1047, 1047, 1047, 1047, 1047,

最佳答案

只需使用set代替list：

#!/usr/bin/python
import MySQLdb, csv
CUSTOMER_CODES = set()

with open('Customers.csv','r') as csvfile:
    reader = csv.DictReader(csvfile)

    for row in reader:
        CUSTOMER_CODES.add(int(row['CUSTOMER_CODE']))

或使用集合理解（假设Python 2.6+）：

#!/usr/bin/python
import MySQLdb, csv

with open('Customers.csv','r') as csvfile:
    reader = csv.DictReader(csvfile)
    CUSTOMER_CODES = {int(row['CUSTOMER_CODE']) for row in reader}

如果要排序列表，请添加CUSTOMER_CODES = sorted(CUSTOMER_CODES)。