在数据帧中插入缺失的lat，lon，每个人有多次旅行

Question

我有以下数据帧（df）并且想要以等距间隔（例如每250米）或时间间隔（例如每2分钟）内插Lat，Lon坐标。

public class JSONParser {
    final String TAG = "JsonParser.java";
    static InputStream is = null;
    static JSONObject jObj = null;
    static String jSon = "";

    public JSONObject getJSONFromURL(String strURL) {
        // TODO Auto-generated method stub

        try {
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(strURL);
            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity entity = httpResponse.getEntity();
            is = entity.getContent();

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder builder = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                builder.append(line + "\n");
            }
            //Log.e("Nitin", "Builder: " + builder.toString());
            is.close();
            jSon = builder.toString();

        } catch (Exception e) {
            Log.e(TAG, "Error converting result " + e.toString());
        }

        try {
            jObj = new JSONObject(jSon);

        } catch (JSONException e) {
            Log.e(TAG, "Error parsing data " + e.toString());
        }
        return jObj;
    }

}

我尝试使用R package zoo和我在类似问题中找到的以下代码：

> head(df)
   ID Latitude Longitude  trip   date.time
1  1 10.30447 -109.2323    1 2005-01-07 11:25:26
2  1 10.30425 -109.2321    1 2005-01-07 11:25:36
3  1 10.30314 -109.2326    1 2005-01-07 11:25:46
4  1 10.30199 -109.2328    1 2005-01-07 11:25:56
5  1 10.30079 -109.2334    1 2005-01-07 11:26:06
6  1 10.30006 -109.2331    1 2005-01-07 11:26:16

但是，由于我的数据框包含多个人（df $ ID）的多次旅行（df $ trip），我收到以下错误消息：

full.time    <- with(df,seq(date.time[1],tail(date.time,1),by=1))
library(zoo)
df.zoo <- zoo(df[,3:4],df$date.time)        # convert to zoo object
result <- na.approx(df.zoo,xout=full.time)  # interpolate; result is also a zoo object
head(result)

如何运行以上代码（循环？）来计算个别旅行？