[Thread Prev][Thread Next][Index]

Re: [las_users] need help for F-TDS data anlaysis



Hi Roland
We kinda miss the ability to type in arbitrary expressions to easily create virtual variables, as in LAS 5.x, 6.x.

In this case, are there any plans to have in LAS 7.x, an option to NOT use F-TDS, but to perhaps use Ferret directly at the backend so that there's no URL-syntax conflicts perhaps?

(We love the new 7.x look and features, but wish the old functionalities like the above could be made to work nicely in 7.x)

Thanks for giving us LAS.

regards
-hengkek

-------- Original Message  --------
Subject: Re: [las_users] need help for F-TDS data anlaysis
From: Roland Schweitzer <Roland.Schweitzer@xxxxxxxx>
To: Wang Jiqin <tmswj@xxxxxxxxxx>
Cc: "las_users@xxxxxxxx" <oar.pmel.las_users@xxxxxxxx>
Date: Wed, 21 Sep 2011 00:40:29 +0800

  Hi,

While it's a nice fantasy to offer users the ability to type in arbitrary expressions for server-side processing, in practice it's much more difficult than we first imagined. First of all are many, many things about the Ferret syntax that are also significant to the URL syntax and no amount of encoding can remove the way they are interpreted by web servers and web clients. Secondly, we quickly discovered that if every newly created variable used as part of a calculation to create a complex expression is exposed in the final data set, the final data set is a mess.

To alleviate the second problem we made the arbitrary decision that only virtual variables that belong to the first data set "/d=1" in Ferret notation will be exposed in the final F-TDS data set. And to alleviate the second problem that let/d=1 a=sst*2 requires a "/" that is significant to the URL syntax we created an alias that is always active for virtual variable created with _expr_ expressions. letdeq1 can be used in place of let/d=1.

So your analysis URL should look like this:

data_coads_climatology.jnl_expr_{}{letdeq1%20A=SST*2}.ascii?A

No doubt our documentation is out of date and we'll get to work on fixing it.

Roland


On 09/15/2011 11:37 PM, Wang Jiqin wrote:

Hi,

We followed the exact step to install and config F-TDS with LAS.

Ferret version: 6.72

Las version: 7.3 (tested on 7.2 too)

OS: RHEL 6

Tomcat Version: 6.0.32

We are able to view

http://IP:8080/thredds/dodsC/las/coads_climatology_cdf/data_coads_climatology.jnl.ascii?SST[0:1:1][0:1:5][0:1:5 <http://IP:8080/thredds/dodsC/las/coads_climatology_cdf/data_coads_climatology.jnl.ascii?SST%5b0:1:1%5d%5b0:1:5%5d%5b0:1:5>]

this is working fine, we can see the values in ascii

However, when doing server data analysis, it returns error.

http://IP:8080/thredds/dodsC/las/coads_climatology_cdf/data_coads_climatology.jnl_expr_%7B%7D%7Blet%20A=SST*2%7D.ascii?A

Error {

    code = 2;

    message = "The variable `A' was not found in the dataset.";

};

Debug logs of ferretIOSP

[...]

I have attached the details logs in the zip file attached.

Please help and thanks in advance.

Regards,

Jiqin




[Thread Prev][Thread Next][Index]


Contact Us
Dept of Commerce / NOAA / OAR / PMEL / TMAP

Privacy Policy | Disclaimer | Accessibility Statement