r - Rラップリーは空のデータフレームを返します

Question

データをリストからデータ フレームに移動しようとしています。次のようなデータパスを実行すると：

RequestData[["rows"]][["elements"]][[1]][["distance"]][["text"]]

私は結果を得る：

[1] "8.4 km"

しかし、関数で同じパスを使用すると:

disData <- lapply(seq_along(RequestData), function(x){         
                  Dis_km <- RequestData[["rows"]][["elements"]][[x]][["distance"]][["text"]]
                  Duration <- RequestData[["rows"]][["elements"]][[x]][["duration"]][["text"]]
                  ID <- all_articles[x,"id"]

                  if (is.data.frame(Dis_km) && nrow(Dis_km)>0){

                    res_df <- data.frame(
                                         distanca=Dis_km,
                                         Duration=Duration,
                                         Id = ID
                                                )
                      }
              }) 

この関数は、空のオブジェクト disData を返します。

備考:関数内のオブジェクト all_articles は、別の独立したデータ フレームです。

このデータはリストにあります: :

RequestData
$destination_addresses
[1] "Maršala Tita 62, Sarajevo 71000, Bosnia and Herzegovina"

$origin_addresses
 [1] "Mustafe Latifića, Sarajevo 71000, Bosnia and Herzegovina"         "Porodice Ribar, Sarajevo 71000, Bosnia and Herzegovina"          
 [3] "Skenderija & Adila Grebe, Sarajevo 71000, Bosnia and Herzegovina" "Azize Šaćirbegović, Sarajevo 71000, Bosnia and Herzegovina"      
 [5] "Bosanska, Sarajevo 71000, Bosnia and Herzegovina"                 "Jezero, Sarajevo 71000, Bosnia and Herzegovina"                  
 [7] "Behdžeta Mutevelića, Sarajevo 71000, Bosnia and Herzegovina"      "Emila Zole, Sarajevo 71000, Bosnia and Herzegovina"              
 [9] "Braće Begić, Sarajevo 71000, Bosnia and Herzegovina"              "Porodice Ribar, Sarajevo 71000, Bosnia and Herzegovina"          
[11] "Nedima Filipovića, Sarajevo 71000, Bosnia and Herzegovina"        "Telali, Sarajevo 71000, Bosnia and Herzegovina"                  
[13] "Ohridska, Sarajevo, Bosnia and Herzegovina"                       "Muse Ćazima Ćatića, Sarajevo 71000, Bosnia and Herzegovina"      
[15] "Džemala Bijedića, Sarajevo, Bosnia and Herzegovina"               "Ferde Hauptmana, Sarajevo 71000, Bosnia and Herzegovina"         
[17] "Bakarevićeva & Bistrik, Sarajevo 71000, Bosnia and Herzegovina"   "Vratnik Mejdan, Sarajevo 71000, Bosnia and Herzegovina"          
[19] "Mis Irbina, Sarajevo 71000, Bosnia and Herzegovina"               "Koševo, Sarajevo 71000, Bosnia and Herzegovina"                  

$rows
                                 elements
1  8.4 km, 8432, 1 hour 47 mins, 6413, OK
2         3.5 km, 3538, 46 mins, 2779, OK
3            0.7 km, 692, 9 mins, 552, OK
4         3.9 km, 3863, 50 mins, 3023, OK
5  6.3 km, 6275, 1 hour 19 mins, 4761, OK
6           0.8 km, 838, 11 mins, 655, OK
7         3.2 km, 3196, 41 mins, 2460, OK
8  7.9 km, 7898, 1 hour 43 mins, 6163, OK
9         2.4 km, 2413, 31 mins, 1842, OK
10        3.5 km, 3538, 46 mins, 2779, OK
11        4.0 km, 4041, 53 mins, 3165, OK
12          0.9 km, 937, 12 mins, 713, OK
13        2.8 km, 2837, 41 mins, 2432, OK
14           0.6 km, 611, 7 mins, 438, OK
15        4.5 km, 4507, 59 mins, 3550, OK
16        4.0 km, 4034, 53 mins, 3162, OK
17         1.0 km, 1039, 14 mins, 814, OK
18        1.6 km, 1564, 20 mins, 1215, OK
19           0.6 km, 595, 8 mins, 470, OK
20        1.9 km, 1883, 24 mins, 1425, OK

$status
[1] "OK"

リスト構造は、最初の要素で次のようになります。

どうしたの？ありがとうございました！