行の値と列の名前を一致させ、各列の最後の値を抽出します

Question

... merge()または他の基底R関数を使用します。

は、例えば、ここでは2つのデータフレームです：

私は V1の行に対応する列の最後の値で V4を持ちたい

V1 V2 V3 
1 DDPC 1747 57.19 
2 DDSG 1466 68.16 
3 DDG 2312 43.2 
4 DDL 2058 48.56 
5 DDUR 1779 56.14 
6 DDTH 1883 53.06 
7 DDAC 2020 49.47 

      DDG DDL DDO DDUR DDAC DDMG DDSG DDTH DDPC DDSUP 
2014-08-05 56.49 61.96 43.81 46.975 51.070 52.27 36.320 NA 1920.21 1364.44 
2014-08-06 56.40 61.88 43.50 46.860 50.850 52.01 36.305 NA 1920.24 1352.94 
2014-08-07 55.79 61.53 43.30 46.310 50.880 51.79 36.105 NA 1909.57 1343.21 
2014-08-08 56.29 61.71 43.78 46.530 50.800 52.27 36.545 NA 1931.59 1334.40 
2014-08-11 56.40 61.95 44.41 46.920 51.190 52.89 36.725 NA 1936.92 1352.42 

：

 V1 V2 V3 V4 
1 DDPC 1747 57.19 1936.92 
2 DDSG 1466 68.16 36.725 
3 DDG 2312 43.2 56.40 
4 DDL 2058 48.56 61.95 
5 DDUR 1779 56.14 46.92 
6 DDTH 1883 53.06 NA 
7 DDAC 2020 49.47 51.19 

thisに見えたが、適切に適用できませんでした。

編集 - また、V3をdf1から取得し、df2の対応する列名の下に割り当てます。V1？

Answer 1

これを試してみてください -

dfa <- data.frame(V1 = letters[1:4], V2 = sample(10,4), V3 = sample(10,4)) 
dfb <- data.frame(a = sample(10,4),b = sample(10,4), c=sample(10,4), d=sample(10,4)) 
dfa['V4'] = unlist(sapply(dfa['V1'],function(x){dfb[nrow(dfb),x]})) 

Answer 2

> dput(A) 
structure(list(V1 = c("DDPC", "DDSG", "DDG", "DDL", "DDUR", "DDTH", 
"DDAC"), V2 = c("1747", "1466", "2312", "2058", "1779", "1883", 
"2020"), V3 = c("57.19", "68.16", "43.2", "48.56", "56.14", "53.06", 
"49.47")), row.names = c(NA, -7L), .Names = c("V1", "V2", 
"V3"), class = "data.frame") 

> dput(B) 
structure(list(Date = c("2014-08-05", "2014-08-06", "2014-08-07", 
"2014-08-08", "2014-08-11"), DDG = c("56.49", "56.4", "55.79", 
"56.29", "56.4"), DDL = c("61.96", "61.88", "61.53", "61.71", 
"61.95"), DDO = c("43.81", "43.5", "43.3", "43.78", "44.41"), 
    DDUR = c("46.975", "46.86", "46.31", "46.53", "46.92"), DDAC = c ("51.07", 
"50.85", "50.88", "50.8", "51.19"), DDMG = c("52.27", "52.01", 
"51.79", "52.27", "52.89"), DDSG = c("36.32", "36.305", "36.105", 
"36.545", "36.725"), DDTH = c(NA_character_, NA_character_, 
NA_character_, NA_character_, NA_character_), DDPC = c("1920.21", 
"1920.24", "1909.57", "1931.59", "1936.92"), DDSUP = c("1364.44", 
"1352.94", "1343.21", "1334.4", "1352.42")), .Names = c("Date", 
"DDG", "DDL", "DDO", "DDUR", "DDAC", "DDMG", "DDSG", "DDTH", 
"DDPC", "DDSUP"), row.names = c(NA, -5L), class = "data.frame") 

コード：

A[,"V4"]=unlist(B[nrow(B),match(A[,1],names(B))]) 
    A 
     V1 V2 V3  V4 
    1 DDPC 1747 57.19 1936.92 
    2 DDSG 1466 68.16 36.725 
    3 DDG 2312 43.2 56.4 
    4 DDL 2058 48.56 61.95 
    5 DDUR 1779 56.14 46.92 
    6 DDTH 1883 53.06 <NA> 
    7 DDAC 2020 49.47 51.19