Documentation

Work with dictionaries

A dictionary type is a collection of key-value pairs with keys of the same type and values of the same type.

Dictionary syntax

A dictionary literal contains a set of key-value pairs (also known as elements) enclosed in square brackets ([]). Elements are comma-delimited. Keys must all be the same type. Values must all be the same type. Keys are associated to values by a colon (:).

Example dictionaries
[0: "Sun", 1: "Mon", 2: "Tue"]

["red": "#FF0000", "green": "#00FF00", "blue": "#0000FF"]

[1.0: {stable: 12, latest: 12}, 1.1: {stable: 3, latest: 15}]

Reference dictionary values

Flux dictionaries are key-indexed. To reference values in a dictionary:

  1. Import the dict package.

  2. Use dict.get() and provide the following parameters:

    • dict: Dictionary to reference
    • key: Key to reference
    • default: Default value to return if the key does not exist
import "dict"

positions =
    [
        "Manager": "Jane Doe",
        "Asst. Manager": "Jack Smith",
        "Clerk": "John Doe",
    ]

dict.get(dict: positions, key: "Manager", default: "Unknown position")
// Returns Jane Doe

dict.get(dict: positions, key: "Teller", default: "Unknown position")
// Returns Unknown position

Operate on dictionaries

Create a dictionary from a list

  1. Import the dict package.
  2. Use dict.fromList() to create a dictionary from an array of records. Each record must have a key and value property.
import "dict"

list = [{key: "k1", value: "v1"}, {key: "k2", value: "v2"}]

dict.fromList(pairs: list)
// Returns [k1: v1, k2: v2]

Insert a key-value pair into a dictionary

  1. Import the dict package.
  2. Use dict.insert() to insert a key-value pair into a dictionary. If the key already exists, it’s overwritten with the new value.
import "dict"

exampleDict = ["k1": "v1", "k2": "v2"]

dict.insert(dict: exampleDict, key: "k3", value: "v3")
// Returns [k1: v1, k2: v2, k3: v3]

Remove a key-value pair from a dictionary

  1. Import the dict package.
  2. Use dict.remove() to remove a key-value pair from a dictionary.
import "dict"

exampleDict = ["k1": "v1", "k2": "v2"]

dict.remove(dict: exampleDict, key: "k2")
// Returns [k1: v1]

Return the string representation of a dictionary

Use display() to return Flux literal representation of a dictionary as a string.

x = ["a": 1, "b": 2, "c": 3]

display(v: x)

// Returns "[a: 1, b: 2, c: 3]"

Include the string representation of a dictionary in a table

Use display() to return Flux literal representation of a dictionary as a string and include it as a column value.

import "sampledata"

sampledata.string()
    |> map(fn: (r) => ({_time: r._time, exampleDict: display(v: ["tag": r.tag, "value":r._value])}))

Output

_time (time) exampleDict (string)
2021-01-01T00:00:00Z [tag: t1, value: smpl_g9qczs]
2021-01-01T00:00:10Z [tag: t1, value: smpl_0mgv9n]
2021-01-01T00:00:20Z [tag: t1, value: smpl_phw664]
2021-01-01T00:00:30Z [tag: t1, value: smpl_guvzy4]
2021-01-01T00:00:40Z [tag: t1, value: smpl_5v3cce]
2021-01-01T00:00:50Z [tag: t1, value: smpl_s9fmgy]
2021-01-01T00:00:00Z [tag: t2, value: smpl_b5eida]
2021-01-01T00:00:10Z [tag: t2, value: smpl_eu4oxp]
2021-01-01T00:00:20Z [tag: t2, value: smpl_5g7tz4]
2021-01-01T00:00:30Z [tag: t2, value: smpl_sox1ut]
2021-01-01T00:00:40Z [tag: t2, value: smpl_wfm757]
2021-01-01T00:00:50Z [tag: t2, value: smpl_dtn2bv]

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