How to Remove Key-Value Pairs from a Map Based on Values in Dart - Step by Step Examples

How to Remove Key-Value Pairs from a Map Based on Values in Dart ?

Answer

To remove key-value pairs from a map in Dart based on values, you need to iterate through the map and check each value. If the value matches the specified condition, remove the corresponding key-value pair.

✐ Examples

1 Removing Key-Value Pairs with Specific Value

We can remove key-value pairs from a map in Dart by iterating through the map and removing pairs with a specific value.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We iterate through the map using the removeWhere method. For each key-value pair, we check if the value matches the specified value 2.
If the value matches, the removeWhere method removes the key-value pair from the map.
We print the contents of the map to the console using the print function to verify that the key-value pairs have been removed.

Dart Program

void main() {
    // Declare and initialize a map
    Map<String, int> myMap = {
        'one': 1,
        'two': 2,
        'three': 3,
        'four': 2
    };

    // Remove key-value pairs with specific value
    myMap.removeWhere((key, value) => value == 2);

    // Print the contents of the map
    print(myMap);
}

Output

{one: 1, three: 3}

2 Removing Key-Value Pairs with a Range of Values

We can remove key-value pairs from a map in Dart by iterating through the map and removing pairs with values within a specified range.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We iterate through the map using the removeWhere method. For each key-value pair, we check if the value falls within the specified range (e.g., between 2 and 3 inclusive).
If the value falls within the range, the removeWhere method removes the key-value pair from the map.
We print the contents of the map to the console using the print function to verify that the key-value pairs have been removed.

Dart Program

void main() {
    // Declare and initialize a map
    Map<String, int> myMap = {
        'one': 1,
        'two': 2,
        'three': 3,
        'four': 4
    };

    // Remove key-value pairs with values in the range [2, 3]
    myMap.removeWhere((key, value) => value >= 2 && value <= 3);

    // Print the contents of the map
    print(myMap);
}

Output

{one: 1, four: 4}

3 Removing Key-Value Pairs with Condition-Based Values

We can remove key-value pairs from a map in Dart by iterating through the map and removing pairs with values that meet a specified condition.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and string values.
We iterate through the map using the removeWhere method. For each key-value pair, we check if the value meets a specified condition (e.g., if the length of the string is 3).
If the condition is met, the removeWhere method removes the key-value pair from the map.
We print the contents of the map to the console using the print function to verify that the key-value pairs have been removed.

Dart Program

void main() {
    // Declare and initialize a map
    Map<String, String> myMap = {
        'one': 'one',
        'two': 'two',
        'three': 'three',
        'four': 'four'
    };

    // Remove key-value pairs where value length is 3
    myMap.removeWhere((key, value) => value.length == 3);

    // Print the contents of the map
    print(myMap);
}

Output

{three: three, four: four}

Summary

In this tutorial, we learned How to Remove Key-Value Pairs from a Map Based on Values in Dart language with well detailed examples.

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How to Remove Key-Value Pairs from a Map Based on Values in Dart - Step by Step Examples