diff --git a/src/lib.zig b/src/lib.zig
index f5881844952bf91c53a2cb4ced03168e2ec597a1..1ff181a17a3da960fe67986f399cb5f341ee4384 100644
--- a/src/lib.zig
+++ b/src/lib.zig
@@ -100,3 +100,4 @@ pub usingnamespace @import("./isIndexable.zig");
 pub usingnamespace @import("./isSlice.zig");
 pub usingnamespace @import("./matchesNone.zig");
 pub usingnamespace @import("./indexOfSlice.zig");
+pub usingnamespace @import("./mapBy.zig");
diff --git a/src/mapBy.zig b/src/mapBy.zig
new file mode 100644
index 0000000000000000000000000000000000000000..3038acd543c3ccfc0b988e7c741d6e7edb455fa5
--- /dev/null
+++ b/src/mapBy.zig
@@ -0,0 +1,19 @@
+const std = @import("std");
+const string = []const u8;
+const extras = @import("./lib.zig");
+
+pub fn mapBy(allocator: std.mem.Allocator, slice: anytype, comptime field: std.meta.FieldEnum(std.meta.Elem(@TypeOf(slice)))) ![]std.meta.FieldType(std.meta.Elem(@TypeOf(slice)), field) {
+    const newslice = try allocator.alloc(std.meta.FieldType(std.meta.Elem(@TypeOf(slice)), field), slice.len);
+    for (newslice, slice) |*i, j| i.* = @field(j, @tagName(field));
+    return newslice;
+}
+
+test {
+    const alloc = std.testing.allocator;
+    const S = struct { x: u32 };
+    const original: []const S = &.{ .{ .x = 53 }, .{ .x = 89 }, .{ .x = 19 }, .{ .x = 44 }, .{ .x = 29 } };
+    const expected: []const u32 = &.{ 53, 89, 19, 44, 29 };
+    const mapped = try mapBy(alloc, original, .x);
+    defer alloc.free(mapped);
+    try std.testing.expectEqualSlices(u32, expected, mapped);
+}