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:
Import the
dictpackage.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
- Insert a key-value pair into a dictionary
- Remove a key-value pair from a dictionary
- Return the string representation of a dictionary
- Include the string representation of a dictionary in a table
Create a dictionary from a list
- Import the
dictpackage. - 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
- Import the
dictpackage. - 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
- Import the
dictpackage. - 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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