My data with a lot of value "?" in some columns, If I want to filter out these columns, which node(s) should I use?
? is the missing value indicator in KNIME. Missing value si somehwat like NULL in databases.
Question is if you want to filter columns or rows? if you want to remove the column, use the column filter. If you want to remove rows that have missing values in a specific column use the row filter.
More specifically, in the Row Filter node, select Exclude Rows, and in the matching section choose "only missing values match"
Row Filter node works for me.