kdb query in matlab r2013a

Community Support
1

hi all,
i can connect to my kdb session from matlab r2013a

>> tab=fetch(q,‘select price:0.5*alast+blast, volume from data where date.year=2013’)

tab = 

     price: [388998x1 double]

    volume: [388998x1 double]

however when my fetch query involves timestamp, i will get a type error

>> tab=fetch(q,‘select time, price:0.5*alast+blast, volume from data where date.year=2013’)

Error using kx/fetch (line 65)

Java exception occurred:

c$KException: type

at c.k(c.java:101)

at c.k(c.java:102)

at c.k(c.java:103)

the time colume is of format date+“p”

2013.01.04D00:44:00.000000000 

the query above doens’t work even if i change time to time.time or time.date

thanks

C

2

things may have changed in last couple of years when i looked at matlab+q but the matlab bridge didn’t seem to support timestamps at that time. Workaround was to cast to a datetime. It looks like you’re only on minute resolution anyway, so hopefully not a problem for you.

Otherwise if you really need nanos, you can convert to a long.

3

It seems to me you are still using an old version of jdbc.jar.  kx has reorganized the jdbc.jar file and put c.jar in a package called kx. <o:p></o:p>

<o:p> </o:p>

I can fetch timestamp.<o:p></o:p>

<o:p> </o:p>

EDU>> javaaddpath ‘jdbc.jar’<o:p></o:p>

EDU>> q = kx.c(‘localhost’,8888)<o:p></o:p>

<o:p></o:p>

q =<o:p></o:p>

<o:p></o:p>

kx.c@24389c<o:p></o:p>

<o:p></o:p>

EDU>> fetch(q,‘.z.p’)<o:p></o:p>

<o:p></o:p>

ans =<o:p></o:p>

<o:p></o:p>

2014-02-20 07:32:23.179023<o:p></o:p>

<o:p> </o:p>

Force an error:<o:p></o:p>

<o:p> </o:p>

EDU>> fetch(q,‘.z.p+`a’)<o:p></o:p>

??? Java exception occurred:<o:p></o:p>

kx.c$KException: type<o:p></o:p>

<o:p> </o:p>

                at kx.c.k(c.java:103)<o:p></o:p>

<o:p> </o:p>

                at kx.c.k(c.java:104)<o:p></o:p>

<o:p> </o:p>

                at kx.c.k(c.java:105)<o:p></o:p>

<o:p> </o:p>

<o:p> </o:p>

Error in ==> fetch at 65<o:p></o:p>

    t = c.handle.k(varargin{1});<o:p></o:p>

<o:p> </o:p>

Can you make sure you are using the latest jdbc.jar file. And if it is still not working can you provide a standalone example with q and matlab scripts?<o:p></o:p>

<o:p> </o:p>

Kim<o:p></o:p>

<o:p> </o:p>

Von: personal-kdbplus@googlegroups.com [mailto:personal-kdbplus@googlegroups.com] Im Auftrag von Manish Patel
Gesendet: Donnerstag, 20. Februar 2014 08:19
An: personal-kdbplus@googlegroups.com
Betreff: Re: [personal kdb+] kdb query in matlab r2013a<o:p></o:p>

<o:p> </o:p>

things may have changed in last couple of years when i looked at matlab+q but the matlab bridge didn’t seem to support timestamps at that time. Workaround was to cast to a datetime. It looks like you’re only on minute resolution anyway, so hopefully not a problem for you.<o:p></o:p>

<o:p> </o:p>

Otherwise if you really need nanos, you can convert to a long.<o:p></o:p>

<o:p> </o:p>

On Thu, Feb 20, 2014 at 12:46 AM, Chao LI <lichaosupper@gmail.com> wrote:<o:p></o:p>

hi all,<o:p></o:p>

i can connect to my kdb session from matlab r2013a<o:p></o:p>

>> tab=fetch(q,‘select price:0.5*alast+blast, volume from data where date.year=2013’)<o:p></o:p>

<o:p> </o:p>

tab = <o:p></o:p>

<o:p> </o:p>

     price: [388998x1 double]<o:p></o:p>

    volume: [388998x1 double]<o:p></o:p>

<o:p> </o:p>

however when my fetch query involves timestamp, i will get a type error<o:p></o:p>

<o:p> </o:p>

>> tab=fetch(q,‘select time, price:0.5*alast+blast, volume from data where date.year=2013’)<o:p></o:p>

Error using kx/fetch (line 65)<o:p></o:p>

Java exception occurred:<o:p></o:p>

c$KException: type<o:p></o:p>

at c.k(c.java:101)<o:p></o:p>

at c.k(c.java:102)<o:p></o:p>

at c.k(c.java:103)<o:p></o:p>

<o:p> </o:p>

the time colume is of format date+“p”<o:p></o:p>

2013.01.04D00:44:00.000000000 <o:p></o:p>

the query above doens’t work even if i change time to time.time or time.date<o:p></o:p>

<o:p> </o:p>

<o:p> </o:p>

thanks<o:p></o:p>

C<o:p></o:p>

–
Submitted via Google Groups

4

Hi Kim,

I am using Matlab 2014a and tried the latest version of jdbc.jar from http://kx.com/q/c/ but the function k = kx(ip, p) still gives me this error:

"Undefined function ‘c’ for input arguments of type ‘char’.

Error in kx (line 63)

Error in KdbTest (line 10)k = kx(host, port);"

When I tried what you suggested k = kx.c(host, port), the connection works and gives an answer of

kx.c@3dcc874a

But then doing fetch(k, ‘.z.p’) gives the following error:

“Undefined function ‘fetch’ for input arguments of type ‘kx.c’.”

Am I using the wrong jdbc.jar version? I made sure that fetch, kx, jdbc.jar etc… were all in my path, but it still doesn’t work.

Any ideas what went wrong?

On Thursday, February 20, 2014 at 3:36:46 PM UTC+8, kuentang wrote:

It seems to me you are still using an old version of jdbc.jar.  kx has reorganized the jdbc.jar file and put c.jar in a package called kx.

 

I can fetch timestamp.

 

EDU>> javaaddpath ‘jdbc.jar’

EDU>> q = kx.c(‘localhost’,8888)

q =

kx.c@24389c

EDU>> fetch(q,‘.z.p’)

ans =

2014-02-20 07:32:23.179023

 

Force an error:

 

EDU>> fetch(q,‘.z.p+`a’)

??? Java exception occurred:

kx.c$KException: type

 

                at kx.c.k(c.java:103)

 

                at kx.c.k(c.java:104)

 

                at kx.c.k(c.java:105)

 

 

Error in ==> fetch at 65

    t = c.handle.k(varargin{1});

 

Can you make sure you are using the latest jdbc.jar file. And if it is still not working can you provide a standalone example with q and matlab scripts?

 

Kim

 

Von: personal…@googlegroups.com [mailto:personal…@googlegroups.com] Im Auftrag von Manish Patel
Gesendet: Donnerstag, 20. Februar 2014 08:19
An: personal…@googlegroups.com
Betreff: Re: [personal kdb+] kdb query in matlab r2013a

 

things may have changed in last couple of years when i looked at matlab+q but the matlab bridge didn’t seem to support timestamps at that time. Workaround was to cast to a datetime. It looks like you’re only on minute resolution anyway, so hopefully not a problem for you.

 

Otherwise if you really need nanos, you can convert to a long.

 

On Thu, Feb 20, 2014 at 12:46 AM, Chao LI <lichao…@gmail.com> wrote:

hi all,

i can connect to my kdb session from matlab r2013a

>> tab=fetch(q,‘select price:0.5*alast+blast, volume from data where date.year=2013’)

 

tab = 

 

     price: [388998x1 double]

    volume: [388998x1 double]

 

however when my fetch query involves timestamp, i will get a type error

 

>> tab=fetch(q,‘select time, price:0.5*alast+blast, volume from data where date.year=2013’)

Error using kx/fetch (line 65)

Java exception occurred:

c$KException: type

at c.k(c.java:101)

at c.k(c.java:102)

at c.k(c.java:103)

 

the time colume is of format date+“p”

2013.01.04D00:44:00.000000000 

the query above doens’t work even if i change time to time.time or time.date

 

 

thanks

C

–
Submitted via Google Groups

5

<o:p> </o:p>

Hi Dave,<o:p></o:p>

<o:p> </o:p>

Sorry for the late reply. Can only reply after work.<o:p></o:p>

<o:p> </o:p>

>>> but the function k = kx(ip, p) still gives me this error<o:p></o:p>

<o:p> </o:p>

Yes, the class c is moved into the package kx, so that’s why the function kx is not working anymore.<o:p></o:p>

<o:p> </o:p>

>>> fetch(k, ‘.z.p’) gives the following error<o:p></o:p>

<o:p> </o:p>

Yes, cause fetch is working on c instead of kx.c. What you need to do is to replace c with kx.c<o:p></o:p>

<o:p> </o:p>

m) kdb = kx.c(‘localhost’,8888)<o:p></o:p>

m) a = fetch(kdb,‘1’)<o:p></o:p>

m) edit fetch<o:p></o:p>

<o:p> </o:p>

This will open the editor to modify the fetch function.<o:p></o:p>

<o:p> </o:p>

Here is a code snippet:<o:p></o:p>

<o:p> </o:p>

kxtype = class(t);<o:p></o:p>

switch kxtype<o:p></o:p>

  <o:p></o:p>

  case ‘c$Dict’<o:p></o:p>

    <o:p></o:p>

    %Get c$Flip components<o:p></o:p>

    tx = t.x;<o:p></o:p>

    ty = t.y;<o:p></o:p>

    tmp = kxout2struct(tx.x,tx.y);<o:p></o:p>

    flds = fieldnames(tmp);<o:p></o:p>

    for i = 1:length(flds)<o:p></o:p>

<o:p> </o:p>

<o:p> </o:p>

As you can see the case is ‘c$Dict’ instead of ‘kx.c$Dict’<o:p></o:p>

<o:p> </o:p>

I remembered I have modified somewhere the c.java class to work directly without the fetch function in matlab. I will send it to you once I have found it<o:p></o:p>

<o:p> </o:p>

HTH,<o:p></o:p>

<o:p> </o:p>

Kim<o:p></o:p>

<o:p> </o:p>

<o:p> </o:p>

<o:p> </o:p>

Von: personal-kdbplus@googlegroups.com [mailto:personal-kdbplus@googlegroups.com] Im Auftrag von dave
Gesendet: Montag, 23. Februar 2015 22:15
An: personal-kdbplus@googlegroups.com
Betreff: Re: [personal kdb+] kdb query in matlab r2013a<o:p></o:p>

<o:p> </o:p>

Hi Kim,

I am using Matlab 2014a and tried the latest version of jdbc.jar from http://kx.com/q/c/ but the function k = kx(ip, p) still gives me this error:<o:p></o:p>

"Undefined function ‘c’ for input arguments of type ‘char’.<o:p></o:p>

Error in kx (line 63)<o:p></o:p>

Error in KdbTest (line 10) k = kx(host, port);"<o:p></o:p>

When I tried what you suggested k = kx.c(host, port), the connection works and gives an answer of<o:p></o:p>

kx.c@3dcc874a<o:p></o:p>

But then doing fetch(k, ‘.z.p’) gives the following error:<o:p></o:p>

“Undefined function ‘fetch’ for input arguments of type ‘kx.c’.”<o:p></o:p>

Am I using the wrong jdbc.jar version? I made sure that fetch, kx, jdbc.jar etc… were all in my path, but it still doesn’t work.<o:p></o:p>

Any ideas what went wrong?<o:p></o:p>

On Thursday, February 20, 2014 at 3:36:46 PM UTC+8, kuentang wrote:<o:p></o:p>

It seems to me you are still using an old version of jdbc.jar.  kx has reorganized the jdbc.jar file and put c.jar in a package called kx. <o:p></o:p>

 <o:p></o:p>

I can fetch timestamp.<o:p></o:p>

 <o:p></o:p>

EDU>> javaaddpath ‘jdbc.jar’<o:p></o:p>

EDU>> q = kx.c(‘localhost’,8888)<o:p></o:p>

q =<o:p></o:p>

kx.c@24389c<o:p></o:p>

EDU>> fetch(q,‘.z.p’)<o:p></o:p>

ans =<o:p></o:p>

2014-02-20 07:32:23.179023<o:p></o:p>

 <o:p></o:p>

Force an error:<o:p></o:p>

 <o:p></o:p>

EDU>> fetch(q,‘.z.p+`a’)<o:p></o:p>

??? Java exception occurred:<o:p></o:p>

kx.c$KException: type<o:p></o:p>

 <o:p></o:p>

                at kx.c.k(c.java:103)<o:p></o:p>

 <o:p></o:p>

                at kx.c.k(c.java:104)<o:p></o:p>

 <o:p></o:p>

                at kx.c.k(c.java:105)<o:p></o:p>

 <o:p></o:p>

 <o:p></o:p>

Error in ==> fetch at 65<o:p></o:p>

    t = c.handle.k(varargin{1});<o:p></o:p>

 <o:p></o:p>

Can you make sure you are using the latest jdbc.jar file. And if it is still not working can you provide a standalone example with q and matlab scripts?<o:p></o:p>

 <o:p></o:p>

Kim<o:p></o:p>

 <o:p></o:p>

Von: personal…@googlegroups.com [mailto:personal…@googlegroups.com] Im Auftrag von Manish Patel
Gesendet: Donnerstag, 20. Februar 2014 08:19
An: personal…@googlegroups.com
Betreff: Re: [personal kdb+] kdb query in matlab r2013a<o:p></o:p>

 <o:p></o:p>

things may have changed in last couple of years when i looked at matlab+q but the matlab bridge didn’t seem to support timestamps at that time. Workaround was to cast to a datetime. It looks like you’re only on minute resolution anyway, so hopefully not a problem for you.<o:p></o:p>

 <o:p></o:p>

Otherwise if you really need nanos, you can convert to a long.<o:p></o:p>

 <o:p></o:p>

On Thu, Feb 20, 2014 at 12:46 AM, Chao LI <lichao…@gmail.com> wrote:<o:p></o:p>

hi all,<o:p></o:p>

i can connect to my kdb session from matlab r2013a<o:p></o:p>

>> tab=fetch(q,‘select price:0.5*alast+blast, volume from data where date.year=2013’)<o:p></o:p>

 <o:p></o:p>

tab = <o:p></o:p>

 <o:p></o:p>

     price: [388998x1 double]<o:p></o:p>

    volume: [388998x1 double]<o:p></o:p>

 <o:p></o:p>

however when my fetch query involves timestamp, i will get a type error<o:p></o:p>

 <o:p></o:p>

>> tab=fetch(q,‘select time, price:0.5*alast+blast, volume from data where date.year=2013’)<o:p></o:p>

Error using kx/fetch (line 65)<o:p></o:p>

Java exception occurred:<o:p></o:p>

c$KException: type<o:p></o:p>

at c.k(c.java:101)<o:p></o:p>

at c.k(c.java:102)<o:p></o:p>

at c.k(c.java:103)<o:p></o:p>

 <o:p></o:p>

the time colume is of format date+“p”<o:p></o:p>

2013.01.04D00:44:00.000000000 <o:p></o:p>

the query above doens’t work even if i change time to time.time or time.date<o:p></o:p>

 <o:p></o:p>

 <o:p></o:p>

thanks<o:p></o:p>

C<o:p></o:p>

–
Submitted via Google Groups