isKey

Determine if dictionary contains key

Since R2022b

Syntax

tf = isKey(d,key)

Description

tf = isKey(d,key) returns a logical 1 (true) if the configured dictionary contains the specified key, and it returns a logical 0 (false) otherwise. If d is an unconfigured dictionary, isKey throws an error.

If key is an array that specifies multiple keys, then tf is a logical array of the same size.

Examples

Find Keys in Dictionary

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"

Determine whether the dictionary has 1 as a key.

tf = isKey(d,1)

tf = logical
   1

Search for multiple keys.

key = [1 2 3 4 5];
tf = isKey(d,key)

tf = 1×5 logical array

   1   1   1   0   0

Input Arguments

d — Dictionary

dictionary object

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

key — Key set

array

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

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• The code generator does not treat a dictionary as a constant, even if the dictionary is constant at code generation time. This means that the isKey function does not return a constant. You cannot pass the output of the isKey function to a function that requires constant inputs. You cannot use the output of the isKey function for operations that require constants, such as indexing into a heterogeneous cell array. The code generator also cannot perform optimizations that depend on constants, such as constant folding, on the output of the isKey function.

For additional considerations that apply when generating C/C++ code for MATLAB^® dictionaries, see Dictionary Limitations for Code Generation (MATLAB Coder).

GPU Code Generation

Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Refer to the usage notes and limitations in the C/C++ Code Generation section. The same usage notes and limitations apply to GPU code generation.

Version History

Introduced in R2022b

R2024b: Code generation support

You can generate C/C++ code for the dictionary isKey function.