拼接字符串 去除所有可能的重复

                   var geoCoords = worldfoot.Replace(" ", "").Replace("\r\n", "").Split(new string[] { "]," }, StringSplitOptions.RemoveEmptyEntries);
                    var distinctGeo = new Dictionary<string, string>();
                    foreach (var item in geoCoords)
                    {
                        var data = item.Split(‘:‘);
                        if (!distinctGeo.ContainsKey(data[0]))
                        {
                            distinctGeo.Add(data[0], item);
                        }
                    }

                    var sb = new StringBuilder();
                    foreach (var item in distinctGeo)
                    {
                        sb.Append(item.Value);
                        sb.AppendLine("],");
                    }
                    worldfoot = sb.ToString();