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transformations:filter

FILTER BY CONDITION

Category: Transform / Filters


Description

This action calculates an expression for every row (without adding a new column) and keeps only rows where this expression is TRUE. All other rows are removed.

If no rows satisfy the condition then all 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.


Use cases

Create subsets of a dataset based on values across multiple columns.

Clean a dataset by removing records that don't meet certain criteria, or evaluate to a certain value.


Action settings

Setting Description
ExpressionEnter an expression that evaluates to a boolean TRUE/FALSE result. The expression will be applied to each
record and remove records that do not meet the criteria (evaluate to FALSE).


Remarks

Examples of valid conditions:

[Amount]=0
  
[Length] * [Width] * [Height] <= 1000
  
contains([City], 'York')
  
not isempty([Email])


Examples

Objective: Find all rivers that are longer than 6000 km.

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


Action parameters:

Expression: [Length (km)] > 6000


Result:

River Length (km) Continent
Nile 6650 Africa
Amazon 6400 South America
Yangtze 6300 Asia
Mississippi 6275 North America


See also

transformations/filter.txt · Last modified: 2021/04/28 14:51 by dmitry