To filter a map based on keys in Dart, you can iterate over the map and add key-value pairs that meet the filter criteria to a new map. This method allows you to create a subset of the original map based on specific key conditions.
We can filter a map based on a range of keys in Dart by iterating over the map and adding key-value pairs that fall within the specified range to a new map.
For example,
myMap
with some key-value pairs. In this example, the map has integer keys and string values.filteredMap
to store the filtered key-value pairs.forEach
method and check if each key falls within the specified range.filteredMap
.print
function to verify the filtering.void main() {
// Declare and initialize a map
Map<int, String> myMap = {
1: 'one',
2: 'two',
3: 'three',
4: 'four',
5: 'five'
};
// Declare an empty map to store the filtered key-value pairs
Map<int, String> filteredMap = {};
// Define the key range
int lowerBound = 2;
int upperBound = 4;
// Iterate over the original map and filter based on the key range
myMap.forEach((key, value) {
if (key >= lowerBound && key <= upperBound) {
filteredMap[key] = value;
}
});
// Print the filtered map
print('Filtered Map by Key Range:');
filteredMap.forEach((key, value) => print('$key: $value'));
}
Filtered Map by Key Range: 2: two 3: three 4: four
We can filter a map based on specific keys in Dart by iterating over the map and adding key-value pairs that match the specified keys to a new map.
For example,
myMap
with some key-value pairs. In this example, the map has integer keys and string values.filteredMap
to store the filtered key-value pairs.forEach
method and check if each key matches one of the specified keys.filteredMap
.print
function to verify the filtering.void main() {
// Declare and initialize a map
Map<int, String> myMap = {
1: 'one',
2: 'two',
3: 'three',
4: 'four',
5: 'five'
};
// Declare an empty map to store the filtered key-value pairs
Map<int, String> filteredMap = {};
// Define the specific keys to filter by
Set<int> keysToFilter = {1, 3, 5};
// Iterate over the original map and filter based on the specific keys
myMap.forEach((key, value) {
if (keysToFilter.contains(key)) {
filteredMap[key] = value;
}
});
// Print the filtered map
print('Filtered Map by Specific Keys:');
filteredMap.forEach((key, value) => print('$key: $value'));
}
Filtered Map by Specific Keys: 1: one 3: three 5: five
We can filter a map with string keys based on a specific prefix in Dart by iterating over the map and adding key-value pairs that have keys starting with the given prefix to a new map.
For example,
myMap
with some key-value pairs. In this example, the map has string keys and string values.filteredMap
to store the filtered key-value pairs.forEach
method and check if each key starts with the specified prefix.filteredMap
.print
function to verify the filtering.void main() {
// Declare and initialize a map
Map<String, String> myMap = {
'apple': 'fruit',
'banana': 'fruit',
'carrot': 'vegetable',
'apricot': 'fruit',
'blueberry': 'fruit'
};
// Declare an empty map to store the filtered key-value pairs
Map<String, String> filteredMap = {};
// Define the prefix to filter by
String prefix = 'ap';
// Iterate over the original map and filter based on the prefix
myMap.forEach((key, value) {
if (key.startsWith(prefix)) {
filteredMap[key] = value;
}
});
// Print the filtered map
print('Filtered Map by Prefix:');
filteredMap.forEach((key, value) => print('$key: $value'));
}
Filtered Map by Prefix: apple: fruit apricot: fruit
In this tutorial, we learned How to Filter a Map Based on Keys in Dart language with well detailed examples.