How to replace null values with previous non null values
I have a column that is something like this
| A | B |
|---|---|
| Value1 | Some Value |
| null | Some Value |
| null | Some Value |
| Value2 | Some Value |
| Value3 | Some Value |
| null | Some Value |
| null | Some Value |
and i want
| A | B |
|---|---|
| Value1 | Some Value |
| Value1 | Some Value |
| Value1 | Some Value |
| Value2 | Some Value |
| Value3 | Some Value |
| Value3 | Some Value |
| Value3 | Some Value |
i have used tjava_row but have encountered certain error. i have used the code given below, or should i go for python(ffill) or pyspark for designing the elt job:
if (row2.A==null) {
row2.A = row1.A
} else {
row2.A=row2.A;
With Talend, you can use a tMap with intern variables to use previous values. You'll need three variables (from the central tab in your tMap) :
current :
row1.yourValue// cache your input data for current lineprevious :
Relational.ISNULL(Var.current)?Var.previous:Var.current//if current line is null, keep the previous one. Otherwise replace 'previous' with current line.getPreviousIfNull :
Relational.ISNULL(row1.yourValue)?Var.previous:Var.current//if your input data is null : get the previous one. Otherwise get the currentone.
row1.yourValue is your input data.
Then you extract Var.getPreviousIfNull to your output.
