PyQ -将数据类型转换为空表
PyQ -将数据类型转换为空表
提问于 2017-12-14 00:41:14
在PyQ中，我可以创建一个字典，并使用翻转来转置它来获得一个表……
q.set(':alpha', q('!', ["Name", "Ask", "Bid", "Time"], ()).flip)然而，不出所料，当我在Q中加载它并检索元数据时，它将所有列的char类型显示为符号……
>>> q.get(':alpha').show()
Name Ask Bid Time
---------------------------------------------------------------
"BTC" "16351.0" "16350.0" "2017-12-12T17:32:33.09"
"ETH" "589.89999993" "585.25" "2017-12-12T17:32:32.697"
"LTC" "297.0" "296.29570358" "2017-12-12T17:32:32.353"
"BTC" "16355.0" "16351.0" "2017-12-12T17:32:44.777"
"ETH" "589.89999993" "585.25" "2017-12-12T17:32:42.15"
"LTC" "297.99940398" "296.29570359" "2017-12-12T17:32:44.433"
"BTC" "16359.99999998" "16350.0" "2017-12-12T17:32:53.713"
"ETH" "589.89999993" "585.2500001" "2017-12-12T17:32:53.197"
"LTC" "297.99940398" "295.0" "2017-12-12T17:32:51.37"
"BTC" "16355.0" "16350.0" "2017-12-12T17:33:02.433"
"ETH" "585.2500001" "585.25" "2017-12-12T17:33:03.497"
"LTC" "297.99940397" "295.0" "2017-12-12T17:33:01.463"
>>> q()
q)\l alpha
`alpha
q)meta alpha
c | t f a
----| -----
Name| s
Ask | s
Bid | s
Time| s
q)我认为这就是当我执行以下查询时，控制台抛出'type错误的原因……
q)select Name, max Ask, max Bid, Time from alpha
'type
q)select max Ask, max Bid, Time by Name from alpha
'type
q)select from alpha where Bid=(max;Bid) fby Name
'type
q)select from alpha where Name=`BTC
Name Ask Bid Time
-----------------我知道在Q中，我可以发出以下命令来实现这一点……
q)alpha:([]Name:`symbol$(); Ask:`float$(); Bid:`float$(); Time:`datetime$())
q)meta alpha
c | t f a
----| -----
Name| s
Ask | f
Bid | f
Time| z
q)为PyQ中的每一列定义字符类型的正确语法是什么？
回答 2
Stack Overflow用户
回答已采纳
发布于 2017-12-16 23:54:44
我将一个datetime char类型传递给一个timestamp列。在Q中，我会将这些定义为...
q)table:([]date:`datetime$(); name:`symbol$())
q)meta table
c | t f a
----| -----
date| z
name| s
q)table:([]date:`timestamp$(); name:`symbol$())
q)meta table
c | t f a
----| -----
date| p
name| s我可以通过将datetime解析为时间戳并转换为K.timestamp([])来解决此问题……
下面的代码...
from bittrex.bittrex import Bittrex, API_V2_0
from datetime import datetime
import time
from pyq import q, K
get_bittrex = Bittrex(None, None)
starttime = time.time()
q.load(':alpha')
while True:
market_result = get_bittrex.get_market_summaries()['result']
for res in market_result:
market_name = res['MarketName']
ask = float(res['Ask'])
bid = float(res['Bid'])
last = float(res['Last'])
volume = float(res['Volume'])
dt = res['TimeStamp']
if market_name in ['USDT-BTC', 'USDT-ETH', 'USDT-LTC', 'USDT-XRP', 'USDT-NEO', 'USDT-BCC', 'USDT-ZEC', 'USDT-XMR', 'USDT-DASH']:
ts = datetime.strptime(dt, '%Y-%m-%dT%H:%M:%S.%f')
data = [market_name[5:], ask, bid, last, volume, ts]
q.upsert(':alpha', [data])
q.get(':alpha').show()
time.sleep(60.0)现在在我的表中返回正确的字符类型...
q)meta alpha
c | t f a
----| -----
Name| s
Ask | f
Bid | f
Last| f
Vol | f
Time| pStack Overflow用户
发布于 2017-12-14 01:37:20
您也可以在PyQ中指定类型：
>>> from pyq import K
>>> q('!', ["Name", "Ask", "Bid", "Time"], [K.symbol([]), K.float([]), K.float([]), K.timestampt([])]).flip.meta.show()
c | t f a
----| -----
Name| s
Ask | f
Bid | f
Time| p或者在您的示例中，您可以使用类似以下内容：
>>> q('!', ["Name", "Ask", "Bid", "Time"], [K.symbol(["LTC-USD","BTC-USD"]),
... K.float([310.,16700.]),
... K.float([310.01,16700.92]),
... K.timestamp([datetime.datetime(2017,12,13,17,40,44), datetime.datetime(2017,12,13,17,40,45)])]).flip.show()
Name Ask Bid Time
----------------------------------------------------
LTC-USD 310 310.01 2017.12.13D17:40:44.000000000
BTC-USD 16700 16700.92 2017.12.13D17:40:45.000000000上面的例子可以进一步简化，因为PyQ知道如何将Python类型转换为Q类型。
>>> q('!', ["Name", "Ask", "Bid", "Time"], [["LTC-USD","BTC-USD"], [310.,16700.], [310.01,16700.92],
... [datetime.datetime(2017,12,13,17,40,44), datetime.datetime(2017,12,13,17,40,45)]]).flip.meta.show()
c | t f a
----| -----
Name| s
Ask | f
Bid | f
Time| p您可以在PyQ的用户指南的Constructs and casts部分中阅读更多内容。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/47798172
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