I’m new to knime and I am trying to migrate an alteryx workflow to knime.
However I am not able to find a tool to do the needed.
PFA the screenshot, I am trying to group by ‘Mix’ column and applying the mentioned formula on a particular group.
I am creating a column ‘new start date’ based on ’ start date’.
The ‘new start date’ is the expected output.
Here, In this formula there are 3 conditions, in the 2nd condition I need to access the previous row of end date and want to call the column ‘new start date’ in the formula itself.
Please suggest how can this be done in knime.
I can’t find any node which can group and apply multi-row formula, and can call the column that we are currently creating.
Do you have any suggestions on how to solve this?
Hi @ArjenEX I tried group loop start which is mentioned in the article but its taking too long.
Is it possible that we can achieve this in the column expression itself?
Also, I need to apply multi - row formula( accessing previous row) on the created column i.e ‘new start date’,basically I need to call the column in the formula that I am currently creating as shown in the screenshot above.
How can I do it on knime?
Hi @denisfi I have already tried this grouby node in knime, but this does not serve my purpose, i need to apply formula on a particular group in a loop format, first i need to group then I need to take one group at a time and apply my formula on it then move to the next group.
I tried doing it by chunk loop node or by group loop start node but its taking forever to run which was hardly taking few minutes in alteryx.
Also in alteryx the column that is being created currently can be called in the formula but in knime I cant find any node which can do so.
Hope I am clear about my requirement!
Well, you can use 2 loop types for it… follow these steps:
1- first at all, order your columns befor the loop session, its pretty important for some types of loop;
2- You can use “Group loop start” to specify 1 or more columns to define a master group like SQL. Example: Date + Category + Sessions
3- Inside this loop, you can make your formula with “Groupby” or add another loop to start your process, breaking in pieces your flow. Example: Chunck loop (for split by number of lines or number of split sizes) or “Generic Loop start” with variable loop end for validate your conditionals.
4- You can use Rules nodes to “test” your conditional and set a new field or chance an exists one…
I need to find a solution which can speed up this process of applying formula to a particular group at a time.
Need a solution for how I can use the column that I am creating in the formula itself, Plus how can I apply the multi row formula on the column that I am currently creating, the way I am doing it in my alteryx multi row formula.
You will need to find another way to reference existing values in your formula results then self referencing a newly created column. It will require a multi-step approach using the Column Expressions node.