Dataframe 1.0 Help

rename

Renames one or several columns without changing its location in DataFrame.

df.rename { columns }.into(name) df.rename { columns }.into { nameExpression } nameExpression = (DataColumn) -> String
df.rename { name }.into("fullName")
df.rename("name").into("fullName")
df.rename { age }.into { val mean = it.data.mean() "age [mean = $mean]" }
df.rename("age").into { val mean = it.data.cast<Int>().mean() "age [mean = $mean]" }

renameToCamelCase

A special case of rename that renames all column names in a DataFrame to "camelCase" format.

This function standardizes column names by converting them from various naming styles—such as "snake_case", "PascalCase", "kebab-case", or "space delimited formats" into a consistent "camelCase" form.

The transformation follows Kotlin naming conventions for variables and properties, making the resulting column names idiomatic and easier to use in Kotlin code, which is especially useful in extension properties usage.

Use it right after loading raw data to normalize column names into a consistent format. This is especially helpful when preparing the data for further transformations, column access, or integration with Kotlin APIs—making the DataFrame easier and more predictable to work with.

Examples

df

Rename selected columns to "camelCase":

df.rename { ColumnA and `COLUMN-C` }.toCamelCase()

Rename all columns (including nested) to "camelCase":

df.renameToCamelCase()

Transformation Rules and Examples

  • Delimiters (underscores, dashes, spaces, etc.) are removed.

  • The first word is kept lowercase; all subsequent words are capitalized.

  • An underscore is inserted between consecutive numbers to improve readability.

  • If a name contains no letters or digits, it remains unchanged.

Original

camelCase

hello_world

helloWorld

HelloWorld

helloWorld

json.parser.Config

jsonParserConfig

my.var_name test

myVarNameTest

thirdColumn

thirdColumn

someHTMLParser

someHtmlParser

RESTApi

restApi

OAuth2Token

oAuth2Token

GraphQLQuery

graphQlQuery

TCP_3_PROTOCOL

tcp3Protocol

123hello_world456

123HelloWorld456

API_Response_2023

apiResponse2023

UPPER_case-LOWER

upperCaseLower

12parse34CamelCase

12Parse34CamelCase

snake_case_example

snakeCaseExample

dot.separated.words

dotSeparatedWords

kebab-case-example

kebabCaseExample

MIXED_Case_with_123Numbers

mixedCaseWith123Numbers

!!!

!!!

1000.2000.3000

1000_2000_3000

UPPERCASE

uppercase

alreadyCamelCased

alreadyCamelCased

justNumbers123

justNumbers123

Just_Special$Chars!!

justSpecialChars

singleword

singleword

word_with_underscores_and-dashes

wordWithUnderscoresAndDashes

10-20-aa

10_20Aa

20 May 2025