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RowKey[{key1,key2,…}]

キー列が値 keyiを持つTabularオブジェクトの行を取り出すために使えるキーを表す．

詳細
Details and Options Details and Options
例題  
例  
スコープ  
アプリケーション  
特性と関係  
関連項目
関連するガイド
履歴
引用書式

RowKey

RowKey[{key1,key2,…}]

キー列が値 keyiを持つTabularオブジェクトの行を取り出すために使えるキーを表す．

詳細

  • RowKeyは，通常，Tabularオブジェクトの行にアクセスするために使われる．
  • 指定されたTabularオブジェクトについて，RowKey[{key1,key2,…}]の中の keyiのリストは各行を一意的に指定しなければならない．
  • RowKey[key]はRowKey[{key}]として理解される．
  • RowKey[…][tab]は，Tabularオブジェクト tab については tab[RowKey[…]]に等しい．

例題

すべて開く すべて閉じる

例  (2)

3列のTabularオブジェクトを作成する：

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

列の一つをキー列に設定し，その列による番号作成を許可する：

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

キー列で"b"を含む行を抽出する：

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

RowKey[…]を関数として使ってキー列があるTabularオブジェクトから行を抽出する：

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

スコープ  (3)

キー列がある Tabularオブジェクトを作成する：

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

キー列に"a"を含む行を抽出する：

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

キー列が1列だけのときは，Listラッパーは必要ない：

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

RowKey[…]をTabularオブジェクトに作用する関数として使う：

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"]]}}]]]]]

G7諸国の人口のTabularオブジェクトを取る：

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"], "Options" -> {}, "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"]]]}}]]]];

2列をキー列として設定する：

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

RowKeyを使って指定された列の値を抽出する：

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

アプリケーション  (1)

各州の死者を伴う衝突事故の表形式データを取る：

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

指定されたキー列はない：

Wolfram Language code: Keys[tab]

列を並べ直して"state"列をキー列に設定する：

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

アメリカ中西部の州の列を抽出する：

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

特性と関係  (4)

キー列があるTabularオブジェクトを取る：

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

行の抽出はRowKeyを使って行える：

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

Keyラッパーは，表形式の行を抽出する際にも使うことができる：

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

TabularオブジェクトのKeysは，キー列が指定されている際はRowKey式のリストを返す：

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

複数のキー列がある場合：

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

RowKey[{key1,key2,…}]を使うと複数のキー列の値で行にインデックスを付けることができる：

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,…]を使うと複数の値で列を指定することができる：

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は，ExtendedKeyオブジェクトで指定された列に対応するキーを含むことができる：

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言語関数， https://reference.wolfram.com/language/ref/RowKey.html.

テキスト

Wolfram Research (2025), RowKey, Wolfram言語関数， 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: 14-November-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: 14-November-2026]}