'numpy.float64'对象没有属性'translate'在Python中将值插入Mysql

Question

import dataset
db = dataset.connect(....)
table = db[...]

当我尝试在Mysql表中插入一些值时,发生了此错误.

我要插入表中的示例值:

print("Buy", ticker, price, date, OType, OSize)
Buy AAPL 93.4357142857 2016-05-12 Market 200
data = dict(Order_Side='Buy',Ticker=ticker, Price=price, 
                            Order_Date= date, Order_Type = OType, Volume = OSize )
table.insert(data)

错误信息:

Traceback (most recent call last):

  File "<ipython-input-3-b7ab0c98f72f>", line 1, in <module>
    runfile('C:/Users/SwigelUser/Documents/GitHub/Trading/Strategies/strat_MA_ExecTest.py', wdir='C:/Users/SwigelUser/Documents/GitHub/Trading/Strategies')

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 880, in runfile
    execfile(filename, namespace)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 102, in execfile
    exec(compile(f.read(), filename, 'exec'), namespace)

  File "C:/Users/SwigelUser/Documents/GitHub/Trading/Strategies/strat_MA_ExecTest.py", line 69, in <module>
    MA_Stra(start_length=7,end_length=10,start_date=date(2016,5,12),end_date=date(2016,6,18))

  File "C:/Users/SwigelUser/Documents/GitHub/Trading/Strategies/strat_MA_ExecTest.py", line 66, in MA_Stra
    table.insert(data1)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\dataset\persistence\table.py", line 87, in insert
    res = self.database.executable.execute(self.table.insert(row))

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\sqlalchemy\engine\base.py", line 945, in execute
    return meth(self, multiparams, params)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\sqlalchemy\sql\elements.py", line 263, in _execute_on_connection
    return connection._execute_clauseelement(self, multiparams, params)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\sqlalchemy\engine\base.py", line 1053, in _execute_clauseelement
    compiled_sql, distilled_params

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\sqlalchemy\engine\base.py", line 1189, in _execute_context
    context)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\sqlalchemy\engine\base.py", line 1405, in _handle_dbapi_exception
    util.reraise(*exc_info)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\sqlalchemy\util\compat.py", line 187, in reraise
    raise value

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\sqlalchemy\engine\base.py", line 1182, in _execute_context
    context)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\sqlalchemy\engine\default.py", line 470, in do_execute
    cursor.execute(statement, parameters)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\pymysql\cursors.py", line 164, in execute
    query = self.mogrify(query, args)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\pymysql\cursors.py", line 143, in mogrify
    query = query % self._escape_args(args, conn)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\pymysql\cursors.py", line 123, in _escape_args
    return dict((key, conn.literal(val)) for (key, val) in args.items())

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\pymysql\cursors.py", line 123, in <genexpr>
    return dict((key, conn.literal(val)) for (key, val) in args.items())

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\pymysql\connections.py", line 821, in literal
    return self.escape(obj, self.encoders)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\pymysql\connections.py", line 814, in escape
    return escape_item(obj, self.charset, mapping=mapping)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\pymysql\converters.py", line 27, in escape_item
    val = encoder(val, mapping)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\pymysql\converters.py", line 110, in escape_unicode
    return u"'%s'" % _escape_unicode(value)

  File "C:\Users\SwigelUser\Anaconda3\lib\site-packages\pymysql\converters.py", line 73, in _escape_unicode
    return value.translate(_escape_table)

AttributeError: 'numpy.float64' object has no attribute 'translate'

是什么导致了这个错误？我怎么能解决这个问题.好像我在这里输入了太多的代码,因此我必须输入很多无意义才能提交.

我的价格和日期变量来自数据框:

for i in range(len(All_Tickers)-1-len(Current_Date),len(All_Tickers)-1):
    price = All_Tickers[str(length) + 'day_MA'][i]
    date = All_Tickers['Date'][i+1]

根据下面的答案,问题应该是价格类型是np.float64,如何将此变量转换为float类型？

Answer 1

您的库尝试将提供的参数格式化为MySQL将理解的格式.为此,它会检查每个参数的类型,以确定应如何格式化输入.

但是,由于您的lib不知道numpy.float64,它会回退到默认编码器,这恰好是字符串(unicode)的编码器.这是相关的代码片段.

def escape_item(val, charset, mapping=None):
    if mapping is None:
        mapping = encoders
    encoder = mapping.get(type(val))

    # Fallback to default when no encoder found
    if not encoder:
        try:
            encoder = mapping[text_type]
        except KeyError:
            raise TypeError("no default type converter defined")

    if encoder in (escape_dict, escape_sequence):
        val = encoder(val, charset, mapping)
    else:
        val = encoder(val, mapping)
    return val

假设输入确实是一个字符串,该编码器尝试translate()在该字符串上调用该方法.但是,由于没有为float64定义此方法,因此会出现此错误.

您应该尝试将float64转换为常规浮点数.

或者,您可以创建自己的编码器,并将其添加到encoders用作python类型到编码器的默认映射的dict中.如果你要使用float64来使用这个lib,那么它可能值得一试.

Answer 2

你可以通过为每个 np.float 变量添加一个 float 方法来解决这个问题，如下所示：

variable = float(variable)

Answer 3

在建立pymysql连接之前，将以下命令添加到任何地方。它添加了新的numpy.float64编码器。

pymysql.converters.encoders[np.float64] = pymysql.converters.escape_float
pymysql.converters.conversions = pymysql.converters.encoders.copy()
pymysql.converters.conversions.update(pymysql.converters.decoders)