Merge pull request #235 from influxdata/flux/stream-table-functions

Stream and table functions

content/v2.0/reference/flux/functions/built-in/transformations/stream-table/_index.md

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+---
+title: Flux stream and table functions
+list_title: Stream and table functions
+seotitle: Flux built-in stream and table functions
+description: >
+  Use stream and table functions to extract a table from a stream of tables and access its
+  columns and records.
+weight: 401
+menu:
+  v2_0_ref:
+    name: Stream & table
+    parent: built-in-transformations
+v2.0/tags: [transformations, built-in, functions, stream, table]
+---
+
+Use stream and table functions to extract a table from a stream of tables and access its
+columns and records.
+
+##### Example stream and table functions
+```js
+data = from(bucket:"example-bucket")
+    |> range(start: -5m)
+    |> filter(fn:(r) => r._measurement == "cpu")
+
+// Extract the first available table for which "_field" is equal to "usage_idle"
+t = data |> tableFind(fn: (key) => key._field == "usage_idle")
+
+// Extract the "_value" column from the table
+values = t |> getColumn(column: "_value")
+
+// Extract the first record from the table
+r0 = t |> getRecord(idx: 0)
+```
+
+{{< children type="functions" >}}

content/v2.0/reference/flux/functions/built-in/transformations/stream-table/getcolumn.md

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+---
+title: getColumn() function
+description: >
+  The `getColumn()` function extracts a column from a table given its label.
+  If the label is not present in the set of columns, the function errors.
+menu:
+  v2_0_ref:
+    name: getColumn
+    parent: Stream & table
+weight: 501
+---
+
+The `getColumn()` function extracts a column from a table given its label.
+If the label is not present in the set of columns, the function errors.
+
+_**Function type:** Stream and table_  
+
+```js
+getColumn(column: "_value")
+```
+
+## Parameters
+
+### column
+The name of the column to extract.
+
+_**Data type:** String_
+
+## Example
+```js
+vs = from(bucket:"example-bucket")
+    |> range(start: -5m)
+    |> filter(fn:(r) => r._measurement == "cpu")
+    |> tableFind(fn: (key) => key._field == "usage_idle")
+    |> getColumn(column: "_value")
+
+// Use column values
+x = vs[0] + vs[1]
+```

content/v2.0/reference/flux/functions/built-in/transformations/stream-table/getrecord.md

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+---
+title: getRecord() function
+description: >
+  The `getRecord()` function extracts a record from a table given its index.
+  If the index is out of bounds, the function errors.
+menu:
+  v2_0_ref:
+    name: getRecord
+    parent: Stream & table
+weight: 501
+---
+
+The `getRecord()` function extracts a record from a table given the record's index.
+If the index is out of bounds, the function errors.
+
+_**Function type:** Stream and table_  
+
+```js
+getRecord(idx: 0)
+```
+
+## Parameters
+
+### idx
+The index of the record to extract.
+
+_**Data type:** Integer_
+
+## Example
+```js
+r0 = from(bucket:"example-bucket")
+    |> range(start: -5m)
+    |> filter(fn:(r) => r._measurement == "cpu")
+    |> tableFind(fn: (key) => key._field == "usage_idle")
+    |> getRecord(idx: 0)
+
+// Use record values
+x = r0._field + "--" + r0._measurement
+```

content/v2.0/reference/flux/functions/built-in/transformations/stream-table/tablefind.md

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+---
+title: tableFind() function
+description: >
+  The `tableFind()` function extracts the first table in a stream of tables whose
+  group key values match a predicate. If no table is found, the function errors.
+menu:
+  v2_0_ref:
+    name: tableFind
+    parent: Stream & table
+weight: 501
+---
+
+The `tableFind()` function extracts the first table in a stream of tables whose
+group key values match a predicate. If no table is found, the function errors.
+
+_**Function type:** Stream and table_  
+
+```js
+tableFind(column: "_value")
+```
+
+## Parameters
+
+### fn
+A predicate function for matching keys in a table's group key.
+`tableFind` returns the first table that resolves as `true`.
+It expects a `key` argument which represents a group key in the input stream.
+
+_**Data type:** Function_
+
+##### Example fn function
+```js
+(key) => key._field == "fieldName"
+```
+
+## Example
+```js
+t = from(bucket:"example-bucket")
+    |> range(start: -5m)
+    |> filter(fn:(r) => r._measurement == "cpu")
+    |> tableFind(fn: (key) => key._field == "usage_idle")
+
+// t represents the first table in a stream whose group key
+// contains "_field" with a value of "usage_idle".
+```
+
+{{% note %}}
+You can use `t` from the example above as input for [`getColumn()`](/v2.0/reference/flux/functions/built-in/transformations/stream-table/getcolumn/)
+and [`getRecord()`](/v2.0/reference/flux/functions/built-in/transformations/stream-table/getrecord/).
+{{% /note %}}