从 R 中的嵌套数据框中提取值

Question

我在 R 中有这个列表，由三个元素组成：

df <- structure(list(`[{"code":"B1182","description":"Tire pressure monitor module","faultInformations":[{"description":"---"},{"description":"TRUE","description_eng":"TRUE","description_fre":"TRUE","description_ger":"TRUE","description_spa":"TRUE","description_ita":"TRUE","description_tur":"TRUE"}],"freezeFrames":[],"enhancedDtcInfos":[],"status":"ACTIVE","system":"MULTIFUNCTION","systemMeta":{"systemName":null,"subSystemName":null},"description_eng":"Tire pressure monitor module","description_fre":"Module de surveillance de la pression des pneus","description_ger":"Reifendrucküberwachung","description_spa":"Módulo de control de la presión de los neumáticos","description_ita":"Modulo monitor di pressione pneumatico","description_tur":"Lastik basıncı izleme modülü"},{"code":"B124D","description":"Sensor, tyre pressure","faultInformations":[{"description":"---"},{"description":"TRUE","description_eng":"TRUE","description_fre":"TRUE","description_ger":"TRUE","description_spa":"TRUE","description_ita":"TRUE","description_tur":"TRUE"}],"freezeFrames":[],"enhancedDtcInfos":[],"status":"ACTIVE","system":"MULTIFUNCTION","systemMeta":{"systemName":null,"subSystemName":null},"description_eng":"Sensor, tyre pressure","description_fre":"Capteur, pression des pneus","description_ger":"Sensor Reifendruck","description_spa":"Sensor de presión del neumático","description_ita":"Sensore, pressione pneumatici","description_tur":"Sensör, lastik hava basıncı"}]` = c("B1182", 
"B124D"), `[{"code":"B1182","description":"Tire pressure monitor module","faultInformations":[{"description":"---"},{"description":"TRUE","description_eng":"TRUE","description_fre":"TRUE","description_ger":"TRUE","description_spa":"TRUE","description_ita":"TRUE","description_tur":"TRUE"}],"freezeFrames":[],"enhancedDtcInfos":[],"status":"ACTIVE","system":"MULTIFUNCTION","systemMeta":{"systemName":null,"subSystemName":null},"description_eng":"Tire pressure monitor module","description_fre":"Module de surveillance de la pression des pneus","description_ger":"Reifendrucküberwachung","description_spa":"Módulo de control de la presión de los neumáticos","description_ita":"Modulo monitor di pressione pneumatico","description_tur":"Lastik basıncı izleme modülü"},{"code":"B124D","description":"Sensor, tyre pressure","faultInformations":[{"description":"---"},{"description":"TRUE","description_eng":"TRUE","description_fre":"TRUE","description_ger":"TRUE","description_spa":"TRUE","description_ita":"TRUE","description_tur":"TRUE"}],"freezeFrames":[],"enhancedDtcInfos":[],"status":"ACTIVE","system":"MULTIFUNCTION","systemMeta":{"systemName":null,"subSystemName":null},"description_eng":"Sensor, tyre pressure","description_fre":"Capteur, pression des pneus","description_ger":"Sensor Reifendruck","description_spa":"Sensor de presión del neumático","description_ita":"Sensore, pressione pneumatici","description_tur":"Sensör, lastik hava basıncı"}]` = c("B1182", 
"B124D"), `[{"code":"B1182","description":"Tire pressure monitor module","faultInformations":[{"description":"---"},{"description":"TRUE","description_eng":"TRUE","description_fre":"TRUE","description_ger":"TRUE","description_spa":"TRUE","description_ita":"TRUE","description_tur":"TRUE"}],"freezeFrames":[],"enhancedDtcInfos":[],"status":"ACTIVE","system":"MULTIFUNCTION","systemMeta":{"systemName":null,"subSystemName":null},"description_eng":"Tire pressure monitor module","description_fre":"Module de surveillance de la pression des pneus","description_ger":"Reifendrucküberwachung","description_spa":"Módulo de control de la presión de los neumáticos","description_ita":"Modulo monitor di pressione pneumatico","description_tur":"Lastik basıncı izleme modülü"},{"code":"B124D","description":"Sensor, tyre pressure","faultInformations":[{"description":"---"},{"description":"TRUE","description_eng":"TRUE","description_fre":"TRUE","description_ger":"TRUE","description_spa":"TRUE","description_ita":"TRUE","description_tur":"TRUE"}],"freezeFrames":[],"enhancedDtcInfos":[],"status":"ACTIVE","system":"MULTIFUNCTION","systemMeta":{"systemName":null,"subSystemName":null},"description_eng":"Sensor, tyre pressure","description_fre":"Capteur, pression des pneus","description_ger":"Sensor Reifendruck","description_spa":"Sensor de presión del neumático","description_ita":"Sensore, pressione pneumatici","description_tur":"Sensör, lastik hava basıncı"}]` = c("B1182", 
"B124D")), .Names = c("[{\"code\":\"B1182\",\"description\":\"Tire pressure monitor module\",\"faultInformations\":[{\"description\":\"---\"},{\"description\":\"TRUE\",\"description_eng\":\"TRUE\",\"description_fre\":\"TRUE\",\"description_ger\":\"TRUE\",\"description_spa\":\"TRUE\",\"description_ita\":\"TRUE\",\"description_tur\":\"TRUE\"}],\"freezeFrames\":[],\"enhancedDtcInfos\":[],\"status\":\"ACTIVE\",\"system\":\"MULTIFUNCTION\",\"systemMeta\":{\"systemName\":null,\"subSystemName\":null},\"description_eng\":\"Tire pressure monitor module\",\"description_fre\":\"Module de surveillance de la pression des pneus\",\"description_ger\":\"Reifendrucküberwachung\",\"description_spa\":\"Módulo de control de la presión de los neumáticos\",\"description_ita\":\"Modulo monitor di pressione pneumatico\",\"description_tur\":\"Lastik basıncı izleme modülü\"},{\"code\":\"B124D\",\"description\":\"Sensor, tyre pressure\",\"faultInformations\":[{\"description\":\"---\"},{\"description\":\"TRUE\",\"description_eng\":\"TRUE\",\"description_fre\":\"TRUE\",\"description_ger\":\"TRUE\",\"description_spa\":\"TRUE\",\"description_ita\":\"TRUE\",\"description_tur\":\"TRUE\"}],\"freezeFrames\":[],\"enhancedDtcInfos\":[],\"status\":\"ACTIVE\",\"system\":\"MULTIFUNCTION\",\"systemMeta\":{\"systemName\":null,\"subSystemName\":null},\"description_eng\":\"Sensor, tyre pressure\",\"description_fre\":\"Capteur, pression des pneus\",\"description_ger\":\"Sensor Reifendruck\",\"description_spa\":\"Sensor de presión del neumático\",\"description_ita\":\"Sensore, pressione pneumatici\",\"description_tur\":\"Sensör, lastik hava basıncı\"}]", 
"[{\"code\":\"B1182\",\"description\":\"Tire pressure monitor module\",\"faultInformations\":[{\"description\":\"---\"},{\"description\":\"TRUE\",\"description_eng\":\"TRUE\",\"description_fre\":\"TRUE\",\"description_ger\":\"TRUE\",\"description_spa\":\"TRUE\",\"description_ita\":\"TRUE\",\"description_tur\":\"TRUE\"}],\"freezeFrames\":[],\"enhancedDtcInfos\":[],\"status\":\"ACTIVE\",\"system\":\"MULTIFUNCTION\",\"systemMeta\":{\"systemName\":null,\"subSystemName\":null},\"description_eng\":\"Tire pressure monitor module\",\"description_fre\":\"Module de surveillance de la pression des pneus\",\"description_ger\":\"Reifendrucküberwachung\",\"description_spa\":\"Módulo de control de la presión de los neumáticos\",\"description_ita\":\"Modulo monitor di pressione pneumatico\",\"description_tur\":\"Lastik basıncı izleme modülü\"},{\"code\":\"B124D\",\"description\":\"Sensor, tyre pressure\",\"faultInformations\":[{\"description\":\"---\"},{\"description\":\"TRUE\",\"description_eng\":\"TRUE\",\"description_fre\":\"TRUE\",\"description_ger\":\"TRUE\",\"description_spa\":\"TRUE\",\"description_ita\":\"TRUE\",\"description_tur\":\"TRUE\"}],\"freezeFrames\":[],\"enhancedDtcInfos\":[],\"status\":\"ACTIVE\",\"system\":\"MULTIFUNCTION\",\"systemMeta\":{\"systemName\":null,\"subSystemName\":null},\"description_eng\":\"Sensor, tyre pressure\",\"description_fre\":\"Capteur, pression des pneus\",\"description_ger\":\"Sensor Reifendruck\",\"description_spa\":\"Sensor de presión del neumático\",\"description_ita\":\"Sensore, pressione pneumatici\",\"description_tur\":\"Sensör, lastik hava basıncı\"}]", 
"[{\"code\":\"B1182\",\"description\":\"Tire pressure monitor module\",\"faultInformations\":[{\"description\":\"---\"},{\"description\":\"TRUE\",\"description_eng\":\"TRUE\",\"description_fre\":\"TRUE\",\"description_ger\":\"TRUE\",\"description_spa\":\"TRUE\",\"description_ita\":\"TRUE\",\"description_tur\":\"TRUE\"}],\"freezeFrames\":[],\"enhancedDtcInfos\":[],\"status\":\"ACTIVE\",\"system\":\"MULTIFUNCTION\",\"systemMeta\":{\"systemName\":null,\"subSystemName\":null},\"description_eng\":\"Tire pressure monitor module\",\"description_fre\":\"Module de surveillance de la pression des pneus\",\"description_ger\":\"Reifendrucküberwachung\",\"description_spa\":\"Módulo de control de la presión de los neumáticos\",\"description_ita\":\"Modulo monitor di pressione pneumatico\",\"description_tur\":\"Lastik basıncı izleme modülü\"},{\"code\":\"B124D\",\"description\":\"Sensor, tyre pressure\",\"faultInformations\":[{\"description\":\"---\"},{\"description\":\"TRUE\",\"description_eng\":\"TRUE\",\"description_fre\":\"TRUE\",\"description_ger\":\"TRUE\",\"description_spa\":\"TRUE\",\"description_ita\":\"TRUE\",\"description_tur\":\"TRUE\"}],\"freezeFrames\":[],\"enhancedDtcInfos\":[],\"status\":\"ACTIVE\",\"system\":\"MULTIFUNCTION\",\"systemMeta\":{\"systemName\":null,\"subSystemName\":null},\"description_eng\":\"Sensor, tyre pressure\",\"description_fre\":\"Capteur, pression des pneus\",\"description_ger\":\"Sensor Reifendruck\",\"description_spa\":\"Sensor de presión del neumático\",\"description_ita\":\"Sensore, pressione pneumatici\",\"description_tur\":\"Sensör, lastik hava basıncı\"}]"
))

当我print(df) 我看到了：

$...
[1] "B1182" "B124D"

$...
[1] "B1182" "B124D"

$...
[1] "B1182" "B124D"

您可以观察到它是一个嵌套的dataframe 和列表，它来自使用jsonlite 提取json 字段。

无论如何，我想将此结果转换为由三行组成的数据框。此外，我想删除所有额外的信息并只保留以前的代码。我该怎么做？

感谢您的帮助。

编辑

我原来的df 包含列表中的2000 多个元素。并非所有这些元素都有两个值，其中一些没有，而另一些则多于两个。

假设我用这个输出打印了六个元素（而不是之前的三个）：

$...
[1] "B1182" "B124D"

$...
[1] "B1182" "B124D"

$...
[1] "B1182" "B124D"

$`[]`
NULL

$...
[1] "B1182" "B124D" "B365A"

$...
[1] "B1182" "B124D"

下面是代码，在对列表的前 20 个元素运行 dput() 后获得：

df <- list(c("B1182", "B124D"), c("B1182", "B124D"), c("B1182", "B124D"
), c("B1182", "B124D"), c("B1182", "B124D"), c("B1182", "B124D"
), c("B1182", "B124D"), c("B1182", "B124D"), NULL, NULL, c("B1182", 
"B124D"), c("B1182", "B124D"), c("B1182", "B124D"), NULL, NULL, 
    NULL, NULL, c("P2000", "P2000", "U3003", "P2000"), c("P2000", 
    "P2000", "U3003", "P2000"), NULL)

在这个更复杂的情况下我们该如何处理？

Answer 1

由于名称很大，我们可以删除名称，然后将 NULL 元素替换为 NA 并行绑定数据。

names(df) <- NULL
df[sapply(df, is.null)] <- NA
dplyr::bind_rows(lapply(df, function(x) 
         as.data.frame(t(x), stringsAsFactors = FALSE)))

#      V1    V2    V3    V4
#1  B1182 B124D  <NA>  <NA>
#2  B1182 B124D  <NA>  <NA>
#3  B1182 B124D  <NA>  <NA>
#4  B1182 B124D  <NA>  <NA>
#5  B1182 B124D  <NA>  <NA>
#6  B1182 B124D  <NA>  <NA>
#...