if statement with math calculation

KNIME Analytics Platform
1

Hi - very new to knime, any idea how I would complete the following combination of steps with multiple nodes? I also wonder if there is a node to store calculation results for step 1 and 2? Just so I can add logic to compare the two results and manipulate from there.

  1. filter price = 1, sum the quantities (in this case 11), multiply the sum by 10. (in this case 110)
  2. Filter price = 2, sum the quantity (in this case 110)
  3. If step 1 = step 2, delete rows where price = 1

Price Quantity
1 2
1 5
1 4
3 32
2 50
2 40
2 20

2

Look at Column Expression node. In step 3 what do you mean sum in step 1 = sum in step 2 or something else?

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3

Hi,
You can calculate step 1 and step 2 by “Math Formula” node (separately). Then you can use “Rule-based Row Filter” node to use the conditions (step 1 = step 2 and price = 1) to filter the rows.

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4

yes so in step 3, if in step 1 (the sum of quantity at price 1 [(2+5+4)*10]) equals step 2 (sum of quantity at price 2 [50+40+20]) then delete all rows with price = 1.

so in this case step 1 = 110, and step 2 = 110, so we would delete the rows where price=1

5

I would add flag column for lines to be compared using Rule Engine with Append Column
IF Price = 1 => True
IF Price = 2 => True
Then use Group by node grouping by New and Sum columns choose max option in Manual Aggregation for price column.

6

how do you do it with mixed column types?
I’m trying this logic:
if season = “spring” then day_of_year - 79,
but in Rule engine it doesn’t seem to accept expressions, and Math node works only with numbers.

7

You can try


node. It may need to be installed first.

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