Query in q-lang using qPython and Pandas in Python 3.8

Question

I am totally new to q-language, but I need to use it in order to access a kdb server to get the data from.

I am using Python 3.8, under Windows10, with qPython installed.

I have trouble getting the query to the server.

from qpython import qconnection
import pandas as pd


tbl = 'q("h\"select from trade where date = 2007.02.28, sym = `XXXX\"")'


q = qconnection.QConnection(host=server, port=server_port, username=user, password=server_password, timeout=server_timeout)

q.open()
df = pd.DataFrame(q.sendSync('tbl'))
q.close()

On executing the script it returns an error at line 15:

qpython.qtype.QException: b'tbl'

So I have a trouble sending the correct expression to the server. I was able to pass the expression via terminal, using q (with PyQ) under Linux Debian 10, so the query is correct.

(The server details are skipped, as well as the bond name).

Matt Moore · Accepted Answer · 2020-02-17 08:16:19Z

1

PyQ and qPython are being confused here. q.sendSync('tbl') will get the variable tbl from the kdb server. This error: qpython.qtype.QException: b'tbl' means tbl doesn't exist on the kdb server. I think what you wanted is the select statement to be sent to the kdb server:

from qpython import qconnection
import pandas as pd

q = qconnection.QConnection(host=server, port=server_port, username=user, password=server_password, timeout=server_timeout, pandas=True)

q.open()
df = q.sendSync('select from trade where date = 2007.02.28, sym = `XXXX')
q.close()

It might be worth while for you to spend sometime with q itself and get up to speed with some basics here:

https://code.kx.com/q4m3/1_Q_Shock_and_Awe/

edited Feb 17, 2020 at 8:16

answered Feb 16, 2020 at 16:00

Matt Moore

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4 Comments

Matthew Over a year ago

Thank you so much about the fix with the query. And even more I thank you about the link. (I actually had seen it in the past, but I thought I would not need to learn Q language in details, as I need just the query.) I have printed df. However I see all the numbers are quite strange. The date for example is listed as '2615'... and all the rest: time, etc.

Matt Moore Over a year ago

import datetime from datetime # if your kdb table has dates and times from my previous answer

Matthew Over a year ago

from qpython import qconnection import pandas as pd from datetime import datetime Still the date and time is not good looking.

Matt Moore Over a year ago

add , pandas = True to qconnection.QConnection. Seems to work for me. May not even need pd.DataFrame

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