benchmark_json_parser.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
using Newtonsoft.Json;

namespace ConsoleApplication1
{
    public struct Benchmark
    {
        private static readonly Regex FunctionNameRegex = new Regex(".{3}_(.*)_mean");
        
        [JsonProperty(PropertyName = "name")] 
        public string Name;

        [JsonProperty(PropertyName = "aggregate_name")]
        public string AggregateName;

        [JsonProperty(PropertyName = "cpu_time")]
        public double CpuTime;
        
        public string FunctionName => FunctionNameRegex.Match(Name).Groups[1].ToString();
    }

    public struct Report
    {
        [JsonProperty(PropertyName = "context")]
        public object Context;

        [JsonProperty(PropertyName = "benchmarks")]
        public IEnumerable<Benchmark> Benchmarks;
    }

    internal class Program
    {
        public static void Main(string[] args)
        {
            var text = File.ReadAllText(@"C:\Users\rir\Documents\out3.json");
            var json = JsonConvert.DeserializeObject<Report>(text);

            var means = json.Benchmarks
                .Where(b => b.AggregateName == "mean")
                .GroupBy(b => b.FunctionName)
                .Select(group => $"{group.Key}, {group.First().CpuTime}, {group.Last().CpuTime}")
                .Aggregate((a, b) => $"{a}\n{b}");

            Console.WriteLine(means);
        }
    }
}