Hello All,
I’m working on a personal project of mine and I’m running into a small issue.
The data set is 3 point percentage and the values being returned is ?
column a | column b | column c
| 2 | 5 | 40.00% |
|---|---|---|
| 0 | 3 | 0.00% |
| 1 | 3 | 33.30% |
| 0 | 0 | ? |
| 1 | 2 | 50.00% |
| 2 | 3 | 66.70% |
| 0 | 1 | 0.00% |
| 0 | 1 | 0.00% |
| 2 | 9 | 22.20% |
| 0 | 4 | 0.00% |
| 0 | 0 | ? |
| 2 | 2 | 100.00% |
how would I go about ignoring every value other than the ? value. Currently I’m using a rule engine to do this. Hope this makes sense!
@sdthamara welcome to the KNIME forum. Dividing by zero (0) will lead to a missing. It seems this is what is happening.
Rule engine seems fine to select or exclude these lines. You might want to think about what you want to do with the data.
I want to keep these rows but I guess 0/0 is undefined.
What can I place in the rule engine to just replace the “?” with say a n/a?
“N/A” will require it to be a string data type, but you can either do it with the Missing Values node or an additional “if statement” line before your calculation on the rule node using MISSING.
Hi @sdthamara and welcome to the Knime Community.
The issue is definitely about x/0 where column b is 0 as already mentioned by @mlauber71.
How are you generating column c (I mean what node and function are you using)? And what should be the results where you have column b = 0? If you are using the Math Formula node, you can always use the if() function. The usage is:
if (cond, trueval, falseval)
So, you could do something like this:
if($column b$ != 0, $column a$/$column b$ * 100, 0)
This will default the result (column c) to 0 if column b is 0, otherwise it will calculate the percentage of column a over column b
But if you are happy with the results, and just want to replace the “?” (empty/missing) by “n/a”, then you can use the Missing Value node. The “?” means it’s an empty value, or a missing value. So the Missing Value node can be used to replace these missing values by whatever you want
Makes sense, I went with iCFO’s suggestion and added a Missing Value Node and that seemed to work.
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