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Excerpt

When data is imported from another system, you might discover that some values are missing in it. In some cases, these values simply contain no content. In other cases, these values are non-existent. Depending on how the missing values entered the data, you may end up processing them in different ways. This section describes how to identify and manage missing data in your datasets.

Info

NOTE: If you are unsure of the meaning of a column of data that contains missing values, you should attempt to review the source data or contact the individual who generated the data to identify why values may be missing and how to effectively manage them in

D s product
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and downstream systems.

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  • missing value is any value that either contains no content or is non-existent. 
    • An example of a non-existent value is a cell in a column of integers that has no value in it. In this special case, the missing value is called a null value
    • Null values are converted to missing values during import. For more information, see Manage Null Values. 
  • Values that are spaces (one or more presses of the SPACEBAR) or tabs (one or more presses of the TAB key) are not missing values.

    Tip

    Tip: To trim whitespace out of a column, use the following transformation:

    D trans
    Typestep
    p01NameColumns
    p01Valuecolumn1
    p02NameFormula
    p02ValueTRIM(column1)
    SearchTermEdit column with formula

    This step may increase the number of missing values (for values that contain only whitespace characters) and the number of instances of matching values (for values that have spaces before and after an alphanumeric value).

  • Return (\n) and newline (\l)  are considered missing.

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Tip

Tip: You can also use the IFMISSING function to test for empty values. Unlike the above construction, however, IFMISSING does not support an else clause when the value is present. For more information, see IFMISSING Function.

 

Copy values from another column

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Info

NOTE: If missing metadata is not supported as part of the value in the target system, you can insert the metadata as a separate column and then apply the metadata to the data inside the target system.

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D s also
inCQLtrue
label((label = "data_type") OR (label = "missing") OR (label = "transformation_ui"))