Как получить имена переменных двойного типа в R

Я пытаюсь просмотреть все имена переменных в данных двойного типа в виде списка в R. Я пытался использовать функцию просмотра, но получил выходные данные в виде фрейма данных, который имел 10571 столбец. Я также попробовал использовать colnames(), я получил результат ниже.

colnames(out.2013.TC_alt)
   [1] "time"      "DIC_1"     "DIC_2"     "DIC_3"     "DIC_4"     "DIC_5"     "DIC_6"     "DIC_7"    
   [9] "DIC_8"     "DIC_9"     "DIC_10"    "DIC_11"    "DIC_12"    "DIC_13"    "DIC_14"    "DIC_15"   
  [17] "DIC_16"    "DIC_17"    "DIC_18"    "DIC_19"    "DIC_20"    "DIC_21"    "DIC_22"    "DIC_23"   
  [25] "DIC_24"    "DIC_25"    "DIC_26"    "DIC_27"    "DIC_28"    "DIC_29"    "DIC_30"    "DIC_31"   
  [33] "DIC_32"    "DIC_33"    "DIC_34"    "DIC_35"    "DIC_36"    "DIC_37"    "DIC_38"    "DIC_39"   
  [41] "DIC_40"    "DIC_41"    "DIC_42"    "DIC_43"    "DIC_44"    "DIC_45"    "DIC_46"    "DIC_47"   
  [49] "DIC_48"    "DIC_49"    "DIC_50"    "DIC_51"    "DIC_52"    "DIC_53"    "DIC_54"    "DIC_55"   
  [57] "DIC_56"    "DIC_57"    "DIC_58"    "DIC_59"    "DIC_60"    "DIC_61"    "DIC_62"    "DIC_63"   
  [65] "DIC_64"    "DIC_65"    "DIC_66"    "DIC_67"    "DIC_68"    "DIC_69"    "DIC_70"    "DIC_71"   
  [73] "DIC_72"    "DIC_73"    "DIC_74"    "DIC_75"    "PhytoC_1"  "PhytoC_2"  "PhytoC_3"  "PhytoC_4" 
  [81] "PhytoC_5"  "PhytoC_6"  "PhytoC_7"  "PhytoC_8"  "PhytoC_9"  "PhytoC_10" "PhytoC_11" "PhytoC_12"
  [89] "PhytoC_13" "PhytoC_14" "PhytoC_15" "PhytoC_16" "PhytoC_17" "PhytoC_18" "PhytoC_19" "PhytoC_20"
  [97] "PhytoC_21" "PhytoC_22" "PhytoC_23" "PhytoC_24" "PhytoC_25" "PhytoC_26" "PhytoC_27" "PhytoC_28"
 [105] "PhytoC_29" "PhytoC_30" "PhytoC_31" "PhytoC_32" "PhytoC_33" "PhytoC_34" "PhytoC_35" "PhytoC_36"
 [113] "PhytoC_37" "PhytoC_38" "PhytoC_39" "PhytoC_40" "PhytoC_41" "PhytoC_42" "PhytoC_43" "PhytoC_44"
 [121] "PhytoC_45" "PhytoC_46" "PhytoC_47" "PhytoC_48" "PhytoC_49" "PhytoC_50" "PhytoC_51" "PhytoC_52"
 [129] "PhytoC_53" "PhytoC_54" "PhytoC_55" "PhytoC_56" "PhytoC_57" "PhytoC_58" "PhytoC_59" "PhytoC_60"
 [137] "PhytoC_61" "PhytoC_62" "PhytoC_63" "PhytoC_64" "PhytoC_65" "PhytoC_66" "PhytoC_67" "PhytoC_68"
 [145] "PhytoC_69" "PhytoC_70" "PhytoC_71" "PhytoC_72" "PhytoC_73" "PhytoC_74" "PhytoC_75" "DiatC_1"  
 [153] "DiatC_2"   "DiatC_3"   "DiatC_4"   "DiatC_5"   "DiatC_6"   "DiatC_7"   "DiatC_8"   "DiatC_9"  
 [161] "DiatC_10"  "DiatC_11"  "DiatC_12"  "DiatC_13"  "DiatC_14"  "DiatC_15"  "DiatC_16"  "DiatC_17" 
 [169] "DiatC_18"  "DiatC_19"  "DiatC_20"  "DiatC_21"  "DiatC_22"  "DiatC_23"  "DiatC_24"  "DiatC_25" 
 [177] "DiatC_26"  "DiatC_27"  "DiatC_28"  "DiatC_29"  "DiatC_30"  "DiatC_31"  "DiatC_32"  "DiatC_33" 
 [185] "DiatC_34"  "DiatC_35"  "DiatC_36"  "DiatC_37"  "DiatC_38"  "DiatC_39"  "DiatC_40"  "DiatC_41" 
 [193] "DiatC_42"  "DiatC_43"  "DiatC_44"  "DiatC_45"  "DiatC_46"  "DiatC_47"  "DiatC_48"  "DiatC_49" 
 [201] "DiatC_50"  "DiatC_51"  "DiatC_52"  "DiatC_53"  "DiatC_54"  "DiatC_55"  "DiatC_56"  "DiatC_57" 
 [209] "DiatC_58"  "DiatC_59"  "DiatC_60"  "DiatC_61"  "DiatC_62"  "DiatC_63"  "DiatC_64"  "DiatC_65" 
 [217] "DiatC_66"  "DiatC_67"  "DiatC_68"  "DiatC_69"  "DiatC_70"  "DiatC_71"  "DiatC_72"  "DiatC_73" 
 [225] "DiatC_74"  "DiatC_75"  "DiatSi_1"  "DiatSi_2"  "DiatSi_3"  "DiatSi_4"  "DiatSi_5"  "DiatSi_6" 
 [233] "DiatSi_7"  "DiatSi_8"  "DiatSi_9"  "DiatSi_10" "DiatSi_11" "DiatSi_12" "DiatSi_13" "DiatSi_14"
 [241] "DiatSi_15" "DiatSi_16" "DiatSi_17" "DiatSi_18" "DiatSi_19" "DiatSi_20" "DiatSi_21" "DiatSi_22"
 [249] "DiatSi_23" "DiatSi_24" "DiatSi_25" "DiatSi_26" "DiatSi_27" "DiatSi_28" "DiatSi_29" "DiatSi_30"
 [257] "DiatSi_31" "DiatSi_32" "DiatSi_33" "DiatSi_34" "DiatSi_35" "DiatSi_36" "DiatSi_37" "DiatSi_38"
 [265] "DiatSi_39" "DiatSi_40" "DiatSi_41" "DiatSi_42" "DiatSi_43" "DiatSi_44" "DiatSi_45" "DiatSi_46"
 [273] "DiatSi_47" "DiatSi_48" "DiatSi_49" "DiatSi_50" "DiatSi_51" "DiatSi_52" "DiatSi_53" "DiatSi_54"
 [281] "DiatSi_55" "DiatSi_56" "DiatSi_57" "DiatSi_58" "DiatSi_59" "DiatSi_60" "DiatSi_61" "DiatSi_62"
 [289] "DiatSi_63" "DiatSi_64" "DiatSi_65" "DiatSi_66" "DiatSi_67" "DiatSi_68" "DiatSi_69" "DiatSi_70"
 [297] "DiatSi_71" "DiatSi_72" "DiatSi_73" "DiatSi_74" "DiatSi_75" "ZooC_1"    "ZooC_2"    "ZooC_3"   
 [305] "ZooC_4"    "ZooC_5"    "ZooC_6"    "ZooC_7"    "ZooC_8"    "ZooC_9"    "ZooC_10"   "ZooC_11"  
 [313] "ZooC_12"   "ZooC_13"   "ZooC_14"   "ZooC_15"   "ZooC_16"   "ZooC_17"   "ZooC_18"   "ZooC_19"  
 [321] "ZooC_20"   "ZooC_21"   "ZooC_22"   "ZooC_23"   "ZooC_24"   "ZooC_25"   "ZooC_26"   "ZooC_27"  
 [329] "ZooC_28"   "ZooC_29"   "ZooC_30"   "ZooC_31"   "ZooC_32"   "ZooC_33"   "ZooC_34"   "ZooC_35"  
 [337] "ZooC_36"   "ZooC_37"   "ZooC_38"   "ZooC_39"   "ZooC_40"   "ZooC_41"   "ZooC_42"   "ZooC_43"  
 [345] "ZooC_44"   "ZooC_45"   "ZooC_46"   "ZooC_47"   "ZooC_48"   "ZooC_49"   "ZooC_50"   "ZooC_51"  
 [353] "ZooC_52"   "ZooC_53"   "ZooC_54"   "ZooC_55"   "ZooC_56"   "ZooC_57"   "ZooC_58"   "ZooC_59"  
 [361] "ZooC_60"   "ZooC_61"   "ZooC_62"   "ZooC_63"   "ZooC_64"   "ZooC_65"   "ZooC_66"   "ZooC_67"  
 [369] "ZooC_68"   "ZooC_69"   "ZooC_70"   "ZooC_71"   "ZooC_72"   "ZooC_73"   "ZooC_74"   "ZooC_75"  
 [377] "DetC_1"    "DetC_2"    "DetC_3"    "DetC_4"    "DetC_5"    "DetC_6"    "DetC_7"    "DetC_8"   
 [385] "DetC_9"    "DetC_10"   "DetC_11"   "DetC_12"   "DetC_13"   "DetC_14"   "DetC_15"   "DetC_16"  
 [393] "DetC_17"   "DetC_18"   "DetC_19"   "DetC_20"   "DetC_21"   "DetC_22"   "DetC_23"   "DetC_24"  
 [401] "DetC_25"   "DetC_26"   "DetC_27"   "DetC_28"   "DetC_29"   "DetC_30"   "DetC_31"   "DetC_32"  
 [409] "DetC_33"   "DetC_34"   "DetC_35"   "DetC_36"   "DetC_37"   "DetC_38"   "DetC_39"   "DetC_40"  
 [417] "DetC_41"   "DetC_42"   "DetC_43"   "DetC_44"   "DetC_45"   "DetC_46"   "DetC_47"   "DetC_48"  
 [425] "DetC_49"   "DetC_50"   "DetC_51"   "DetC_52"   "DetC_53"   "DetC_54"   "DetC_55"   "DetC_56"  
 [433] "DetC_57"   "DetC_58"   "DetC_59"   "DetC_60"   "DetC_61"   "DetC_62"   "DetC_63"   "DetC_64"  
 [441] "DetC_65"   "DetC_66"   "DetC_67"   "DetC_68"   "DetC_69"   "DetC_70"   "DetC_71"   "DetC_72"  
 [449] "DetC_73"   "DetC_74"   "DetC_75"   "DetN_1"    "DetN_2"    "DetN_3"    "DetN_4"    "DetN_5"   
 [457] "DetN_6"    "DetN_7"    "DetN_8"    "DetN_9"    "DetN_10"   "DetN_11"   "DetN_12"   "DetN_13"  
 [465] "DetN_14"   "DetN_15"   "DetN_16"   "DetN_17"   "DetN_18"   "DetN_19"   "DetN_20"   "DetN_21"  
 [473] "DetN_22"   "DetN_23"   "DetN_24"   "DetN_25"   "DetN_26"   "DetN_27"   "DetN_28"   "DetN_29"  
 [481] "DetN_30"   "DetN_31"   "DetN_32"   "DetN_33"   "DetN_34"   "DetN_35"   "DetN_36"   "DetN_37"  
 [489] "DetN_38"   "DetN_39"   "DetN_40"   "DetN_41"   "DetN_42"   "DetN_43"   "DetN_44"   "DetN_45"  
 [497] "DetN_46"   "DetN_47"   "DetN_48"   "DetN_49"   "DetN_50"   "DetN_51"   "DetN_52"   "DetN_53"  
 [505] "DetN_54"   "DetN_55"   "DetN_56"   "DetN_57"   "DetN_58"   "DetN_59"   "DetN_60"   "DetN_61"  
 [513] "DetN_62"   "DetN_63"   "DetN_64"   "DetN_65"   "DetN_66"   "DetN_67"   "DetN_68"   "DetN_69"  
 [521] "DetN_70"   "DetN_71"   "DetN_72"   "DetN_73"   "DetN_74"   "DetN_75"   "DetP_1"    "DetP_2"   
 [529] "DetP_3"    "DetP_4"    "DetP_5"    "DetP_6"    "DetP_7"    "DetP_8"    "DetP_9"    "DetP_10"  
 [537] "DetP_11"   "DetP_12"   "DetP_13"   "DetP_14"   "DetP_15"   "DetP_16"   "DetP_17"   "DetP_18"  
 [545] "DetP_19"   "DetP_20"   "DetP_21"   "DetP_22"   "DetP_23"   "DetP_24"   "DetP_25"   "DetP_26"  
 [553] "DetP_27"   "DetP_28"   "DetP_29"   "DetP_30"   "DetP_31"   "DetP_32"   "DetP_33"   "DetP_34"  
 [561] "DetP_35"   "DetP_36"   "DetP_37"   "DetP_38"   "DetP_39"   "DetP_40"   "DetP_41"   "DetP_42"  
 [569] "DetP_43"   "DetP_44"   "DetP_45"   "DetP_46"   "DetP_47"   "DetP_48"   "DetP_49"   "DetP_50"  
 [577] "DetP_51"   "DetP_52"   "DetP_53"   "DetP_54"   "DetP_55"   "DetP_56"   "DetP_57"   "DetP_58"  
 [585] "DetP_59"   "DetP_60"   "DetP_61"   "DetP_62"   "DetP_63"   "DetP_64"   "DetP_65"   "DetP_66"  
 [593] "DetP_67"   "DetP_68"   "DetP_69"   "DetP_70"   "DetP_71"   "DetP_72"   "DetP_73"   "DetP_74"  
 [601] "DetP_75"   "DetSi_1"   "DetSi_2"   "DetSi_3"   "DetSi_4"   "DetSi_5"   "DetSi_6"   "DetSi_7"  
 [609] "DetSi_8"   "DetSi_9"   "DetSi_10"  "DetSi_11"  "DetSi_12"  "DetSi_13"  "DetSi_14"  "DetSi_15" 
 [617] "DetSi_16"  "DetSi_17"  "DetSi_18"  "DetSi_19"  "DetSi_20"  "DetSi_21"  "DetSi_22"  "DetSi_23" 
 [625] "DetSi_24"  "DetSi_25"  "DetSi_26"  "DetSi_27"  "DetSi_28"  "DetSi_29"  "DetSi_30"  "DetSi_31" 
 [633] "DetSi_32"  "DetSi_33"  "DetSi_34"  "DetSi_35"  "DetSi_36"  "DetSi_37"  "DetSi_38"  "DetSi_39" 
 [641] "DetSi_40"  "DetSi_41"  "DetSi_42"  "DetSi_43"  "DetSi_44"  "DetSi_45"  "DetSi_46"  "DetSi_47" 
 [649] "DetSi_48"  "DetSi_49"  "DetSi_50"  "DetSi_51"  "DetSi_52"  "DetSi_53"  "DetSi_54"  "DetSi_55" 
 [657] "DetSi_56"  "DetSi_57"  "DetSi_58"  "DetSi_59"  "DetSi_60"  "DetSi_61"  "DetSi_62"  "DetSi_63" 
 [665] "DetSi_64"  "DetSi_65"  "DetSi_66"  "DetSi_67"  "DetSi_68"  "DetSi_69"  "DetSi_70"  "DetSi_71" 
 [673] "DetSi_72"  "DetSi_73"  "DetSi_74"  "DetSi_75"  "NH4_1"     "NH4_2"     "NH4_3"     "NH4_4"    
 [681] "NH4_5"     "NH4_6"     "NH4_7"     "NH4_8"     "NH4_9"     "NH4_10"    "NH4_11"    "NH4_12"   
 [689] "NH4_13"    "NH4_14"    "NH4_15"    "NH4_16"    "NH4_17"    "NH4_18"    "NH4_19"    "NH4_20"   
 [697] "NH4_21"    "NH4_22"    "NH4_23"    "NH4_24"    "NH4_25"    "NH4_26"    "NH4_27"    "NH4_28"   
 [705] "NH4_29"    "NH4_30"    "NH4_31"    "NH4_32"    "NH4_33"    "NH4_34"    "NH4_35"    "NH4_36"   
 [713] "NH4_37"    "NH4_38"    "NH4_39"    "NH4_40"    "NH4_41"    "NH4_42"    "NH4_43"    "NH4_44"   
 [721] "NH4_45"    "NH4_46"    "NH4_47"    "NH4_48"    "NH4_49"    "NH4_50"    "NH4_51"    "NH4_52"   
 [729] "NH4_53"    "NH4_54"    "NH4_55"    "NH4_56"    "NH4_57"    "NH4_58"    "NH4_59"    "NH4_60"   
 [737] "NH4_61"    "NH4_62"    "NH4_63"    "NH4_64"    "NH4_65"    "NH4_66"    "NH4_67"    "NH4_68"   
 [745] "NH4_69"    "NH4_70"    "NH4_71"    "NH4_72"    "NH4_73"    "NH4_74"    "NH4_75"    "NO3_1"    
 [753] "NO3_2"     "NO3_3"     "NO3_4"     "NO3_5"     "NO3_6"     "NO3_7"     "NO3_8"     "NO3_9"    
 [761] "NO3_10"    "NO3_11"    "NO3_12"    "NO3_13"    "NO3_14"    "NO3_15"    "NO3_16"    "NO3_17"   
 [769] "NO3_18"    "NO3_19"    "NO3_20"    "NO3_21"    "NO3_22"    "NO3_23"    "NO3_24"    "NO3_25"   
 [777] "NO3_26"    "NO3_27"    "NO3_28"    "NO3_29"    "NO3_30"    "NO3_31"    "NO3_32"    "NO3_33"   
 [785] "NO3_34"    "NO3_35"    "NO3_36"    "NO3_37"    "NO3_38"    "NO3_39"    "NO3_40"    "NO3_41"   
 [793] "NO3_42"    "NO3_43"    "NO3_44"    "NO3_45"    "NO3_46"    "NO3_47"    "NO3_48"    "NO3_49"   
 [801] "NO3_50"    "NO3_51"    "NO3_52"    "NO3_53"    "NO3_54"    "NO3_55"    "NO3_56"    "NO3_57"   
 [809] "NO3_58"    "NO3_59"    "NO3_60"    "NO3_61"    "NO3_62"    "NO3_63"    "NO3_64"    "NO3_65"   
 [817] "NO3_66"    "NO3_67"    "NO3_68"    "NO3_69"    "NO3_70"    "NO3_71"    "NO3_72"    "NO3_73"   
 [825] "NO3_74"    "NO3_75"    "PO4_1"     "PO4_2"     "PO4_3"     "PO4_4"     "PO4_5"     "PO4_6"    
 [833] "PO4_7"     "PO4_8"     "PO4_9"     "PO4_10"    "PO4_11"    "PO4_12"    "PO4_13"    "PO4_14"   
 [841] "PO4_15"    "PO4_16"    "PO4_17"    "PO4_18"    "PO4_19"    "PO4_20"    "PO4_21"    "PO4_22"   
 [849] "PO4_23"    "PO4_24"    "PO4_25"    "PO4_26"    "PO4_27"    "PO4_28"    "PO4_29"    "PO4_30"   
 [857] "PO4_31"    "PO4_32"    "PO4_33"    "PO4_34"    "PO4_35"    "PO4_36"    "PO4_37"    "PO4_38"   
 [865] "PO4_39"    "PO4_40"    "PO4_41"    "PO4_42"    "PO4_43"    "PO4_44"    "PO4_45"    "PO4_46"   
 [873] "PO4_47"    "PO4_48"    "PO4_49"    "PO4_50"    "PO4_51"    "PO4_52"    "PO4_53"    "PO4_54"   
 [881] "PO4_55"    "PO4_56"    "PO4_57"    "PO4_58"    "PO4_59"    "PO4_60"    "PO4_61"    "PO4_62"   
 [889] "PO4_63"    "PO4_64"    "PO4_65"    "PO4_66"    "PO4_67"    "PO4_68"    "PO4_69"    "PO4_70"   
 [897] "PO4_71"    "PO4_72"    "PO4_73"    "PO4_74"    "PO4_75"    "DSi_1"     "DSi_2"     "DSi_3"    
 [905] "DSi_4"     "DSi_5"     "DSi_6"     "DSi_7"     "DSi_8"     "DSi_9"     "DSi_10"    "DSi_11"   
 [913] "DSi_12"    "DSi_13"    "DSi_14"    "DSi_15"    "DSi_16"    "DSi_17"    "DSi_18"    "DSi_19"   
 [921] "DSi_20"    "DSi_21"    "DSi_22"    "DSi_23"    "DSi_24"    "DSi_25"    "DSi_26"    "DSi_27"   
 [929] "DSi_28"    "DSi_29"    "DSi_30"    "DSi_31"    "DSi_32"    "DSi_33"    "DSi_34"    "DSi_35"   
 [937] "DSi_36"    "DSi_37"    "DSi_38"    "DSi_39"    "DSi_40"    "DSi_41"    "DSi_42"    "DSi_43"   
 [945] "DSi_44"    "DSi_45"    "DSi_46"    "DSi_47"    "DSi_48"    "DSi_49"    "DSi_50"    "DSi_51"   
 [953] "DSi_52"    "DSi_53"    "DSi_54"    "DSi_55"    "DSi_56"    "DSi_57"    "DSi_58"    "DSi_59"   
 [961] "DSi_60"    "DSi_61"    "DSi_62"    "DSi_63"    "DSi_64"    "DSi_65"    "DSi_66"    "DSi_67"   
 [969] "DSi_68"    "DSi_69"    "DSi_70"    "DSi_71"    "DSi_72"    "DSi_73"    "DSi_74"    "DSi_75"   
 [977] "O2_1"      "O2_2"      "O2_3"      "O2_4"      "O2_5"      "O2_6"      "O2_7"      "O2_8"     
 [985] "O2_9"      "O2_10"     "O2_11"     "O2_12"     "O2_13"     "O2_14"     "O2_15"     "O2_16"    
 [993] "O2_17"     "O2_18"     "O2_19"     "O2_20"     "O2_21"     "O2_22"     "O2_23"     "O2_24"    
 [ reached getOption("max.print") -- omitted 9571 entries ]

Этот out.2013.TC_alt имеет двойной тип.

typeof(out.2013.TC_alt)
"double"

Я ожидал список переменных, таких как O2, DSi, NH4, NO3, DiatC, DetN, DetP, DetSi, PO4, Sal, DIC, PhytoC, DiatSi, DetC, ZooC.