Method ZipMap

ZipMap<TSource, TResult>(IEnumerable<TSource>, Func<TSource, TResult>)

Applies a function to each element in a sequence and returns a sequence of tuples containing both the original item as well as the function result.

Declaration

public static IEnumerable<(TSource item, TResult result)> ZipMap<TSource, TResult>(this IEnumerable<TSource> source, Func<TSource, TResult> selector)

Parameters

Type	Name	Description
IEnumerable<TSource>	source	A sequence of values to invoke a transform function on
Func<TSource, TResult>	selector	A transform function to apply to each source element

Returns

Type	Description
IEnumerable<(TSource item, TResult result)>	An IEnumerable<T> whose elements are a tuple of the original element and the item returned from calling the selector on that element.

Type Parameters

Name	Description
TSource	The type of the elements of source
TResult	The type of the value returned by selector

Remarks

This operator uses deferred execution and streams its results.

Examples

The following code example demonstrates how to generate a sequence of values and a projection of that value using ZipMap.

var sequence = new[] { "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", };

// Filter a sequence based on a leading value
var result = sequence
    .ZipMap(x => x.ToString().Length);

Console.WriteLine(
    "[" +
    string.Join(", ", result) +
    "]");

// This code produces the following output:
// [(one, 3), (two, 3), (three, 5), (four, 4), (five, 4), (six, 3), (seven, 5), (eight, 5), (nine, 4), (ten, 3)]

Exceptions

Type	Condition
ArgumentNullException	source or selector is null.