Page tree

 

Contents:


In the Trifacta® application, you can rename individual columns through the column drop-down. Through transform steps, you can apply renaming to one or more columns.

NOTE: An imported dataset requires about 15 rows to properly infer column data types and the row, if any, to use for column headers.

Name Requirements

  • Column names are case-insensitive and cannot begin with whitespace.
  • Column names cannot contain escaped characters, such as \n.

NOTE: When publishing to Avro, Parquet, or database tables,

column names support alphanumeric characters and the underscore (_) character only. Column names cannot begin with a numeral. Other characters cause an error to occur.


NOTE: Column names with spaces or special characters in a transformation must be wrapped by curly braces. Example:

column1,{Column 2 with space},column3

Tip: To prevent potential issues with downstream systems, you should limit your column lengths to no more than 128 characters.

Rename Individual Columns

Rename a column through column menu

To rename a column, click the drop-down caret next to the column name. Click Rename.

Rename a column through suggestions

Steps:

  1. If your column already exists, click the name of the column. 
  2. Click the Rename suggestion card.
  3. Click Modify.
  4. Replace the newColumnName value with your preferred column name.

Rename a column through transformation

You can use the following transformation to rename a single column through the Transform Builder. In this case, the Rename columns transformation is used to perform a manual rename of MySourceCol to MyNewCol.

Transformation Name Rename columns
Parameter: Option Manual rename
Parameter: Column MySourceCol
Parameter: New name MyNewCol

Rename a new column

Columns that are generated through transform steps are given a default name. 

For the following types of transforms, however, you can specify the column name as part of the step:

  • derive
  • extractkv
  • merge
  • nest

When a transform is added to the recipe, an as: clause is automatically added to the transform step. You can modify your transform to change the value of the as: column. For example, the following transform generates a new column with the first word from the Name column. The as: value renames this generated column as FirstName:

Transformation Name New formula
Parameter: Formula type Single row formula
Parameter: Formula FIND(Name,`{start} `,false,0)
Parameter: New name FirstName

Auto-Generated Column Names

When your transforms generate new columns, names are automatically assigned to these columns based on the following pattern. 

  1. If the transform includes a function reference, the function name is included in the new column. Example:

    Transformation Name New formula
    Parameter: Formula type Single row formula
    Parameter: Formula LEFT(city,3)


    New column name: left_city

  2. If the above step is applied again, a duplicate column is generated with the following name. Example:

    Transformation Name New formula
    Parameter: Formula type Single row formula
    Parameter: Formula LEFT(city,3)


    New column name: left_city1

  3. If the transform does not contain a function reference, the following convention is used:

    Transformation Name New formula
    Parameter: Formula type Single row formula
    Parameter: Formula 'A'

    New column name: column1

    Transformation Name New formula
    Parameter: Formula type Single row formula
    Parameter: Formula 'B'

    New column name: column2

Rename Multiple Columns

Trifacta Wrangler Pro enables to rename multiple columns using a single transformation. You can perform this batch renaming using one of the methods described in this section.

NOTE: In macros, Rename Columns transformations do not work. This is a known issue.

Tip: To prevent potential issues with downstream systems, you should limit your column lengths to no more than 128 characters.


Steps:

  1. Open the Transform Builder to add a new step to your recipe. 
  2. From the drop-down in the first textbox, select Rename columns.
  3. Select your method of renaming. See below.
  4. Select the column or columns to which to apply the rename.

    Tip: To apply the renaming across all columns in the dataset, select All. This option is useful for pattern-based renames, such as adding a prefix or changing case.

  5. To add the step to your recipe, click Add.

Manual rename multiple columns

For each column that you select, you must add the new name just below the old one. 

  • To add additional columns to the mapping, click Add.
  • To remove columns from the mapping, click Remove.

Add prefix

For the selected columns, you can apply a specific prefix value to the names.

Old Column NamesPrefixNew Column Names
column1pre_pre_column1
column2pre_pre_column2
column3pre_pre_column3

Transformation:

Transformation Name Rename columns
Parameter: Option Add prefix
Parameter: Column column1,column2,column3
Parameter: Prefix pre_

Add suffix

For the selected columns, you can apply a specific suffix value to the names. Example:

Old Column NamesSuffixNew Column Names
column1_newcolumn1_new
column2_newcolumn2_new
column3_newcolumn3_new

Transformation:

Transformation Name Rename columns
Parameter: Option Add suffix
Parameter: Column column1,column2,column3
Parameter: Suffix _new

Apply rename to all columns

The following transformation performs the same rename as the previous one. Instead, it uses the All option to apply the rename across all columns of the dataset. If the number of columns changes in the future, then the rename is still applied across all of the columns in the dataset.

Transformation:

Transformation Name Rename columns
Parameter: Option Add suffix
Parameter: Columns All
Parameter: Suffix _new

Convert to lowercase

For the selected columns, you can convert the columns names to lowercase. Example:

Old Column NamesNew Column Names
Dailydaily
POS_Costpos_cost
Sales_Typesales_type

Transformation:

Transformation Name Rename columns
Parameter: Option Convert to lowercase
Parameter: Column Daily,POS_Cost,Sales_Type

For example, if the old column name is Sales_Type, then the new column name is renamed to sales_type.

Convert to UPPERCASE

For the selected columns, you can convert the columns names to uppercase. Example:

Old Column NamesNew Column Names
Daily

DAILY

POS_CostPOS_COST
Sales_TypeSALES_TYPE

Transformation:

Transformation Name Rename columns
Parameter: Option Convert to UPPERCASE
Parameter: Column Daily,POS_Cost,Sales_Type

For example, if the old column name is Sales_Type, then the new column name is renamed to SALES_TYPE.

Keep from beginning (left)

For the selected columns, you can specify the number of characters to keep from the beginning (left) of the column names.  Based on the number of characters you provide, the column name is updated. Example:

Old Column NamesNumber of charactersNew Column Names
Daily3

Dai

POS_Cost3POS
Sales_Type3Sal

Transformation:

Transformation Name Rename columns
Parameter: Option Keep from beginning (left)
Parameter: Column Daily,POS_Cost,Sales_Type
Parameter: Number of characters 3

For example, if the old column name is Sales_Type, then based on the number of characters to keep from the beginning (left) is 3, then new column name is renamed to Sal.

Keep from end (right)

For the selected columns, you can specify the number of characters to keep from end (right) of the column names.  Based on the number of characters you provide, the column name is updated. Example:

Old Column NamesNumber of charactersNew Column Names
Daily4

aily

POS_Cost4Cost
Sales_Type4Type

Transformation:

Transformation Name Rename columns
Parameter: Option Keep from beginning (right)
Parameter: Column Daily,POS_Cost,Sales_Type
Parameter: Number of characters 4

For example, if the old column name is Sales_Type, then based on the number of characters to keep from the end (right) is 4, then new column name is renamed to Type.

NOTE: If the number of characters are more than the length of the column names, then the whole name of the column is retained.

Find and replace

You can apply literals,  Patterns , or regular expressions to match patterns of text in the source column names. These matching values can then be replaced by a fixed value.

Tip: The default behavior is to replace the first instance. Use the Match all occurrences checkbox to apply the pattern matching across all columns in your set.

For the selected columns, you can specify the number of characters to keep from end (right) of the column names.  Based on the number of characters you provide, the column name is updated. Example:

Old Column NamesNew Column Names
column1

Field1

column2

Field2

column3

Field3

Transformation:

Transformation Name Rename columns
Parameter: Option Find and replace
Parameter: Column column1,column2,column3
Parameter: Find 'column'
Parameter: Replace with 'Field'

The above uses literal values for find and replace. For more information on pattern-based matching, see Text Matching.

Use row(s) as column names

When this method is applied, all of the values in the specified row or rows are used as the new names for each column.

NOTE: This method applies to all columns in the dataset.

Types:

TypeDescription
Use a single row to rename columns

Specify the row number in the sample to use as the source for column names.

NOTE: Source row number information must be available. See below.

Use the first row in the sample to rename columns Use the first row in the sample as the name for all columns.
Combine multiple rows to rename columns

Specify two or more rows to combine into column names. Details are below.

NOTE: Source row number information must be available. See below.

Source row number information:

NOTE: If source row number information is no longer available, this method cannot be used for column rename.

  • If a value is not applied for the source row number, the next row of data is used.
  • Source row numbers apply. Current row numbers may not be the same. In the data grid, mouse over the leftmost column to see available row information.
  • Each value in the row or combination of values across rows must be unique within the set of new column names.
  • The row is removed from its original position.
  • If the product is unable to find unique multi-row headers for the column, the first row of the header set is used.

Combine multiple rows

The following transformation renames the columns in the dataset based on the values in rows 3 and 4 of the data:

Transformation Name Rename columns
Parameter: Option Use row(s) as column names
Parameter: Type Combine multiple rows to name columns
Parameter: Row Numbers - row A 3
Parameter: Row Numbers - row B 4
Parameter: Choose your separator '_'
Parameter: Fill across? Selected

In the above:

  • The separator is defined as an underscore character (_). This value can be empty.
  • When Fill across is selected, if any row value is empty, the last non-empty value for the row in a previous column is used as part of the column header.

This page has no comments.