attaching a header/MetaData to a BufferedDataTable

Node Development
1

Hi all, I'm back to Knime dev after a few years,

I want to write a plugin that would read a tab-delimited file with a header. Something like this:

##Header
##TAG1=40
##TAG2=40
#COL1  COL2  COL3
1      TAG2   4
1      TAG1   5
1      TAG2   6

 

to get the semantics of the 2nd column (e.g TAG1), I need to have and access to the header (TAG1==40)

It I put my data in a BufferedDataTable, is there a way to 'attach 'the header to the table (as a String  is ok) , the header would follow the workflow + it would be saved when the workbench is closed.

 

What is the best way to achieve this ? Thanks.

 

2

Hi.

I don't think you can attach headers to a table, but maybe you could implement a custom cell type, with pointers to your internal lookup table? That seems more in line with the principles of the platform, and also more extensible in the future.

3

Thanks Marlin,

you meant that each CustomCell would carry a copy of the 'Header' ?  Wouldn't it  be a huge resource (with many data duplicated ) to save  ?

As an example the size of one header is  ~10k bytes

 

P.

4

Every data column spec can carry user-defined DataColumnProperties (essentially a map). There you can store your semantic column information.

5

@thor,

got it: https://tech.knime.org/docs/api/org/knime/core/data/DataColumnProperties.html

it looks like a nice solution, I will look at this

thanks !