lookup

Find value in dictionary by key

Since R2023b

Syntax

``value = lookup(d,key)``
``value = lookup(d,key,FallbackValue=fallback)``

Description

example

````value = lookup(d,key)` returns the value corresponding to `key` in `dictionary`, `d`. If no entry corresponds to `key` then `lookup` throws an error.`value = lookup(d,key)` is equivalent to ```value = d(key)```.```

example

````value = lookup(d,key,FallbackValue=fallback)` specifies a fallback value to return if `key` is not found in `d`.The `lookup` function does not validate `fallback` unless a fallback value is required. An error is not thrown unless `key` is not found, even if `lookup` is invalid. ```

Examples

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Create a dictionary containing several key-value pairs.

```names = ["Unicycle" "Bicycle" "Tricycle"]; wheels = [1 2 3]; d = dictionary(wheels,names)```
```d = dictionary (double --> string) with 3 entries: 1 --> "Unicycle" 2 --> "Bicycle" 3 --> "Tricycle" ```

Look up a value.

`v = lookup(d,1)`
```v = "Unicycle" ```

Create a dictionary containing several key-value pairs.

```names = ["Unicycle" "Bicycle" "Tricycle"]; wheels = [1 2 3]; d = dictionary(wheels,names)```
```d = dictionary (double --> string) with 3 entries: 1 --> "Unicycle" 2 --> "Bicycle" 3 --> "Tricycle" ```

Look up a value with a fallback value if it is not found.

`v = lookup(d,[3,5],FallbackValue="Wheeled Vehicle")`
```v = 1x2 string "Tricycle" "Wheeled Vehicle" ```

Input Arguments

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Dictionary, specified as a `dictionary` object. If `d` is unconfigured, `lookup` throws an error.

Key set, specified as an array. The data type of `key` must match or be convertible to the data type of keys in `d`.

Fallback value, specified as a scalar containing the value to return if `key` is not found. The data type of `fallback` must match or be convertible to the data type of values in `d`. `fallback` is not validated unless `key` is not found.

Example: `FallbackValue="Wheeled Vehicle"`

Version History

Introduced in R2023b