python - 理解期间列表中的python类型

我有一个如下的sql查询字符串：

intro text,
id int,
description varchar(50)

我正在尝试创建一个类型字符串，目的是查找与sql模式中定义的类型不匹配的文本。我从sql文本中提取类型的方式如下：

types = [re.sub('[^a-zA-Z]','',x.split()[1]) for x in schema]
types = [re.sub('varchar',types.StringType,x) for x in types]
types = [re.sub('text',types.StringType,x) for x in types]
types = [re.sub('bigint',types.IntType,x) for x in types]
types = [re.sub('decimal',types.IntType,x) for x in types]

但是口译员抱怨说

types = [re.sub('varchar',types.StringTypes,x) for x in types]
AttributeError: 'list' object has no attribute 'StringTypes'

SSCCE

使用以下架构文件

intro text,
id int,
description varchar(50)

和代码（注意，如下面的奥斯卡建议的那样已修复，但现在有其他错误）

import csv
import sys
import re
import types

sch = open(sys.argv[1], "rb")

#---------------------------------
# read schema
#---------------------------------
with sch as f:
    schema = f.read().splitlines()

#---------------------------------
# extract schema types
#---------------------------------

foundtypes = [re.sub('[^a-zA-Z]','',x.split()[1]) for x in schema]
foundtypes = [re.sub('varchar',str,x) for x in foundtypes]
foundtypes = [re.sub('text',str,x) for x in foundtypes]
foundtypes = [re.sub('int',int,x) for x in foundtypes]
foundtypes = [re.sub('bigint',int,x) for x in foundtypes]
foundtypes = [re.sub('decimal',int,x) for x in foundtypes]

print foundtypes

我正在使用Python 2.7.5

谢谢

最佳答案

您在以下行中将绑定（请参见：variable shadowing）改写为types module：

types = [re.sub('[^a-zA-Z]','',x.split()[1]) for x in schema]

之后，types不再指向模块，而是指向列表。只需在所有作业中使用另一个名称即可：

my_types = [re.sub('[^a-zA-Z]','',x.split()[1]) for x in schema]
my_types = [re.sub('varchar',types.StringType,x) for x in my_types]
my_types = [re.sub('text',types.StringType,x) for x in my_types]
my_types = [re.sub('bigint',types.IntType,x) for x in my_types]
my_types = [re.sub('decimal',types.IntType,x) for x in my_types]

更新

我认为您对解决方案进行了过度设计，除了第一行以外，这不适合使用正则表达式。一个简单的if-elif-else可以正常工作：

def transform(typestr):
    if typestr in ('varchar', 'text'):
        return types.StringType
    elif typestr in ('int', 'bigint', 'decimal'):
        return types.IntType
    else:
        return None

my_types = [re.sub(r'[^a-zA-Z]', '', x.split()[1]) for x in schema]
[transform(x) for x in my_types]
=> [<type 'str'>, <type 'int'>, <type 'str'>]

关于python - 理解期间列表中的python类型，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/22952000/