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RowKey[{key1,key2,…}]

represents a key that can be used to extract the row of a Tabular object for which the key columns have values keyi.

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Basic Examples  
Scope  
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RowKey

RowKey[{key1,key2,…}]

represents a key that can be used to extract the row of a Tabular object for which the key columns have values keyi.

Details

  • RowKey is typically used to access rows of a Tabular object.
  • For a given Tabular object, the list of keyi in RowKey[{key1,key2,…}] must uniquely specify each row.
  • RowKey[key] is understood as RowKey[{key}].
  • RowKey[…][tab] is equivalent to tab[RowKey[…]] for a Tabular object tab.

Examples

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Basic Examples  (2)

Create a Tabular object with three columns:

Wolfram Language code: Tabular[{{1, "a", 2.}, {4, "b", 3.}}, {"col1", "col2", "col3"}]

Set one of them to be a key column, to allow indexing by that column:

Wolfram Language code: tab = Tabular[%, <|"KeyColumns" -> {"col2"}|>]

Extract the row containing "b" in the key column:

Wolfram Language code: tab[RowKey[{"b"}]]
Wolfram Language code: %//Normal

Use RowKey[…] as a function to extract a row from a Tabular object with a key column:

Wolfram Language code: EntityValue[{Entity["Country", "France"], Entity["Country", "Italy"]}, {"GDP", "Area"}, "Tabular"]
Wolfram Language code: %//RowKey[Entity["Country", "France"]]// Normal

Scope  (3)

Create a Tabular object with a key column:

Wolfram Language code: tab = Tabular[{{"a", 2.}, {"b", 3.}}, <|"ColumnKeys" -> {"col1", "col2"}, "KeyColumns" -> {"col1"}|>]

Extract the row containing "a" in the key column:

Wolfram Language code: tab[RowKey[{"a"}]]
Wolfram Language code: %//Normal

The List wrapper is not needed when there is a single key column:

Wolfram Language code: tab[RowKey["a"]]

Use RowKey[…] as a function acting on a Tabular object:

Wolfram Language code: RowKey[{"b"}][Tabular[Association["RawSchema" -> Association["ColumnProperties" -> Association["col1" -> Association["ElementType" -> "String"], "col2" -> Association["ElementType" -> "Real64"]], "KeyColumns" -> {"col1"}, "Backend" -> "WolframKernel"], "Options" -> {}, "BackendData" -> Association["ColumnData" -> DataStructure["ColumnTable", {{TabularColumn[Association["Data" -> {{3, {0, 1, 2}, "ab"}, {}, None}, "ElementType" -> "String"]], TabularColumn[Association["Data" -> {{2., 3.}, {}, None}, "ElementType" -> "Real64"]]}}]]]]]

Take a Tabular object of populations of the G7 countries:

Wolfram Language code: tab = Tabular[Association["RawSchema" -> Association["ColumnProperties" -> Association["Year" -> Association["ElementType" -> "Integer64"], "Country" -> Association["ElementType" -> "String"], "Population" -> Association["ElementType" -> TypeSpecifier["Quantity"]["Real64", "People"]]], "KeyColumns" -> None, "Backend" -> "WolframKernel"], "BackendData" -> Association["ColumnData" -> DataStructure["ColumnTable", {{TabularColumn[Association["Data" -> {{1950, 1950, 1950, 1950, 1950, 1950, 1950, 2000, 2000, 2000, 2000, 2000, 2000, 2000}, {}, None}, "ElementType" -> "Integer64"]], TabularColumn[Association["Data" -> {{3, {0, 6, 12, 19, 24, 29, 42, 54, 60, 66, 73, 78, 83, 96, 108}, "CanadaFranceGermanyItalyJapanUnitedKingdomUnitedStatesCanadaFranceGermanyI\ talyJapanUnitedKingdomUnitedStates"}, {}, None}, "ElementType" -> "String"]], TabularColumn[Association["Data" -> {14, {{{1.3737*^7, 4.1828673*^7, 6.8377*^7, 4.7104*^7, 8.31996*^7, 5.0127*^7, 1.513258*^8, 3.0529607*^7, 5.8494936*^7, 8.1561598*^7, 5.6950733*^7, 1.26664952*^8, 5.8734782*^7, 2.80816627*^8}, {}, None}}, None}, "ElementType" -> TypeSpecifier["Quantity"]["Real64", "People"]]]}}]]]];

Set two columns as key columns:

Wolfram Language code: Tabular[tab, <|"KeyColumns" -> {"Year", "Country"}|>]

Use RowKey to extract a value for a given column:

Wolfram Language code: %[RowKey[{2000, "Italy"}], "Population"]

Applications  (1)

Take tabular data of fatal collisions for each state:

Wolfram Language code: tab = ResourceData["Sample Tabular Data: Fatal Collisions"]
Wolfram Language code: ColumnKeys[tab]

There are no key columns specified:

Wolfram Language code: Keys[tab]

Reorder the columns and set the "state" column as key column:

Wolfram Language code: neworder = RotateRight[ColumnKeys[tab]]
Wolfram Language code: newtab = Tabular[tab[All, neworder], <|"KeyColumns" -> {"state"}|>]
Wolfram Language code: Keys[newtab]

Extract the rows for US Midwest states:

Wolfram Language code: midwest = EntityValue[EntityClass["AdministrativeDivision", "USStatesMidwest"], EntityProperty["AdministrativeDivision", "StateAbbreviation"]]
Wolfram Language code: Tabular[newtab[RowKey[#]]& /@ midwest, <|"KeyColumns" -> {"state"}|>]

Properties & Relations  (4)

Take a Tabular object with a key column:

Wolfram Language code: tab = Tabular[{{"one", True, "foo"}, {"two", False, "bar"}}, <|"ColumnKeys" -> {"key", "col1", "col2"}, "KeyColumns" -> {"key"}|>]

Row extraction can be performed with RowKey:

Wolfram Language code: tab[RowKey["one"]]

Key wrappers can also be used to extract a tabular row:

Wolfram Language code: tab[Key["one"]]

Keys of a Tabular object returns a list of RowKey expressions if key columns are specified:

Wolfram Language code: Tabular[{{"cat", 2, 3}, {"dog", 5, 6}}, <|"ColumnKeys" -> {"a", "b", "c"}, "KeyColumns" -> {"a"}|>]
Wolfram Language code: Keys[%]

For multiple key columns:

Wolfram Language code: Tabular[{{"cat", 2, 3}, {"dog", 5, 6}}, <|"ColumnKeys" -> {"a", "b", "c"}, "KeyColumns" -> {"a", "b"}|>]
Wolfram Language code: Keys[%]

RowKey[{key1,key2,…}] allows indexing rows by the values of multiple key columns:

Wolfram Language code: Tabular[Association["RawSchema" -> Association["ColumnProperties" -> Association["a" -> Association["ElementType" -> "String"], "b" -> Association["ElementType" -> "Integer64"], "c" -> Association["ElementType" -> "Integer64"]], "KeyColumns" -> {"a", "b"}, "Backend" -> "WolframKernel"], "BackendData" -> Association["ColumnData" -> DataStructure["ColumnTable", {{TabularColumn[Association["Data" -> {{3, {0, 3, 6}, "catdog"}, {}, None}, "ElementType" -> "String"]], TabularColumn[Association["Data" -> {{2, 5}, {}, None}, "ElementType" -> "Integer64"]], TabularColumn[Association["Data" -> {{3, 6}, {}, None}, "ElementType" -> "Integer64"]]}}]]]][RowKey[{"cat", 2}]]
Wolfram Language code: %//Normal

ExtendedKey[key1,key2,…] allows specifying columns by multiple values:

Wolfram Language code: Tabular[Association["RawSchema" -> Association["ColumnProperties" -> Association[ExtendedKey["female", "name"] -> Association["ElementType" -> "String"], ExtendedKey["female", "city"] -> Association["ElementType" -> "String"]], "KeyColumns" -> None, "Backend" -> "WolframKernel"], "BackendData" -> Association["ColumnData" -> DataStructure["ColumnTable", {{TabularColumn[Association["Data" -> {{3, {0, 4, 13}, "AnnaElizabeth"}, {}, None}, "ElementType" -> "String"]], TabularColumn[Association[ "Data" -> {{3, {0, 7, 12}, "ChicagoParis"}, {}, None}, "ElementType" -> "String"]]}}]]]][All, ExtendedKey["female", "city"]]
Wolfram Language code: %//Normal

RowKey can contain keys corresponding to columns specified by ExtendedKey objects:

Wolfram Language code: tab = Tabular[Association["RawSchema" -> Association["ColumnProperties" -> Association[ExtendedKey["first", "name"] -> Association["ElementType" -> "String"], ExtendedKey["first", "a"] -> Association["ElementType" -> "Integer64"], ExtendedKey["first", "b"] -> Association["ElementType" -> "Integer64"], ExtendedKey["second", "name"] -> Association["ElementType" -> "String"], ExtendedKey["second", "a"] -> Association["ElementType" -> "Integer64"], ExtendedKey["second", "b"] -> Association["ElementType" -> "Integer64"]], "KeyColumns" -> {ExtendedKey["first", "name"], ExtendedKey["second", "name"]}, "Backend" -> "WolframKernel"], "Options" -> {}, "BackendData" -> Association["ColumnData" -> DataStructure["ColumnTable", {{TabularColumn[Association["Data" -> {{3, {0, 3, 6}, "catdog"}, {}, None}, "ElementType" -> "String"]], TabularColumn[Association["Data" -> {{2, 5}, {}, None}, "ElementType" -> "Integer64"]], TabularColumn[Association["Data" -> {{3, 6}, {}, None}, "ElementType" -> "Integer64"]], TabularColumn[Association[ "Data" -> {{3, {0, 4, 9}, "rosetulip"}, {}, None}, "ElementType" -> "String"]], TabularColumn[Association["Data" -> {{7, 10}, {}, None}, "ElementType" -> "Integer64"]], TabularColumn[Association["Data" -> {{8, 11}, {}, None}, "ElementType" -> "Integer64"]]}}]]]];
Wolfram Language code: tab[RowKey[{"cat", "rose"}]]
Wolfram Language code: %//Normal
Wolfram Research (2025), RowKey, Wolfram Language function, https://reference.wolfram.com/language/ref/RowKey.html.

Text

Wolfram Research (2025), RowKey, Wolfram Language function, https://reference.wolfram.com/language/ref/RowKey.html.

CMS

Wolfram Language. 2025. "RowKey." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/RowKey.html.

APA

Wolfram Language. (2025). RowKey. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/RowKey.html

BibTeX

@misc{reference.wolfram_2026_rowkey, author="Wolfram Research", title="{RowKey}", year="2025", howpublished="\url{https://reference.wolfram.com/language/ref/RowKey.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_rowkey, organization={Wolfram Research}, title={RowKey}, year={2025}, url={https://reference.wolfram.com/language/ref/RowKey.html}, note=[Accessed: 13-June-2026]}