transformations:filter
This is an old revision of the document!
Filter by Condition
This transformation calculates an expression for every row (without adding a new column) and keeps only rows where this expression is true. Other rows are removed.
The expression must be a valid condition – it must return either TRUE or FALSE for any row in the table. If it results in a non-boolean value (i.e. not TRUE or FALSE) for at least one row it will cause a project execution error.
Examples of conditions
[Amount]=0 [Length] * [Width] * [Height] <= 1000 contains([City], 'York') not isempty([Email])
If no rows satisfy the condition then all rows are removed.
Example of transformation
Source table: The longest rivers in the world
River | Length (km) | Continent |
---|---|---|
Nile | 6650 | Africa |
Amazon | 6400 | South America |
Yangtze | 6300 | Asia |
Mississippi | 6275 | North America |
Yenisei | 5539 | Asia |
Yellow River | 5464 | Asia |
Ob | 5410 | Asia |
Paraná | 4880 | South America |
Objective: Find all rivers that are longer than 6000 km
Transformation parameters:
- Column: Length (km)
- Expression: [Length (km)] > 6000
Output table:
River | Length (km) | Continent |
---|---|---|
Nile | 6650 | Africa |
Amazon | 6400 | South America |
Yangtze | 6300 | Asia |
Mississippi | 6275 | North America |
See also
transformations/filter.1434158459.txt.gz · Last modified: 2015/06/12 21:20 by dmitry