Filename as column

KNIME Analytics Platform
1

Dear sir

I am now doing text processing by importing few hundred text documents via flat file reader node and would like to add the filename as one of the columns so as to facilitate tables joining from other output from flat file reader. Can you suggest the way of doing this?

Thanks
Lawson

2

There's multiple ways to do this. You could use the List Files node to list all the files and then iterate over this table to import them. 

Or if you are manually configuring the reader you can output the filepath via a flow variable by naming it on the flow variables dialog tab.

 

Cheers

Sam

3

Thanks Sam.

Regarding to the Flow Variable option, is it only applicable to file path, not filename?  Or I need to use other node to extract the filename seprately from the file path?

Thanks
Lawson

4

URL to File Path node will extract name for you.

5

Sorry I didn't pay enough attention earlier, you will need to conver to extract the filename from the path using for example the URL to FIle Path as above or the some regex. 

6

Hi Sam,

Thanks for suggesting the URL node. I am new to KNIME and could use some help in the same topic as well.

I have multiple .csv files so I created the following nodes:

List Files >  URL Path > Table Row To Variable > CSV Reader > Loop End.

I can see the filename as Flow variable. How can I get it to show up as a column header in the data?

Thanks,

Armand

7

hi armand_ink,

 

i don't know if this answer your question, but i solve it in this way...

i used variable to table row, to extract only the URL, then i used URL to file Path Node and after this the cross joiner to mege both tables...(all in the loop)

After the END LOOP i got a table with filenames/location for every row...

 

2 Likes
8

Hi Andi,

Perfect, I got it to work with your sugestion.

Thank you so much!!

Armand

9

@Andi, I built my workflow based on your image, but I want each file to be saved with the new column or at least appended to a master table that has the file name column. But when I run the loop is just pulls in the next file, adds the column, dumps it an reuns etc.

How are these nodes configured to actually allow me to change the file itself in order to add the filename column and change the actual .CSV file or at least have a master table in my workflow that I can then export?

10

@TardisPilot
i take some new pictures of the test-workflow. Hope this will help you. If you have questions, don’t hesitate to contact me :slight_smile:

1_workflow
1_workflow1368×629 41.9 KB
2_list_file_node
3_csv_reader
3_csv_reader703×569 26.4 KB
4_row_filter
4_row_filter627×605 16.2 KB
4_string_manipul
4_string_manipul869×623 23.9 KB
5_csv_writer
5_csv_writer591×560 28 KB

1 Like
11

Hi, @Andi !

I have tried to follow your steps, seems like I m missing something in here.
I would like to get files names wo creating new column for each filename
I stuck in URl to File Path
Can you please look at this?
I have to get filename (here month and year from file) for each file
new_file.knwf (1.7 MB)

12

Hello there,

with KNIME version 4.4.0 you can use Append path column option to have file identifier when reading one or more files into KNIME. See here for more:

Br,
Ivan

2 Likes