有条件地替换数据框中的值

Question

I have two dataframes with seven descriptive data columns and a variable number of additional analysis columns (based on earlier steps in the code). I want to replace some of the values in the analysis columns of dataframe1 with the corresponding values in dataframe2 based on a Boolean value in the first column of dataframe1 .

dataframe1 :

structure(list(compare = c(1, 1, 0, 1, 1, 1, 0, 1), ID_TREE = 29338:29345, 
    ID_PLOT = c(1068L, 1068L, 1068L, 1068L, 1068L, 1068L, 1068L, 
    1068L), ID_CATEGORY = c(3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L), 
    ID_WOOD_SPGR_GREENVOL_DRYWT = c(28L, 28L, 28L, 7L, 28L, 28L, 
    28L, 28L), ID_BARK_SPGR_GREENVOL_DRYWT = c(25L, 25L, 25L, 
    18L, 25L, 25L, 25L, 25L), ID_BARK_VOL_PCT = c(2L, 2L, 2L, 
    10L, 2L, 2L, 2L, 2L), VOLCFGRS = c(3.21875, 6.576453125, 
    12.2406407654729, 0.863593268246, 1.15809306543472, 0.755301358016, 
    13.6662694477056, 4.549483421824)), row.names = c(NA, -8L
), class = c("data.table", "data.frame"), .internal.selfref = <pointer: (nil)>)

dataframe2 :

structure(list(compare = c(1, 1, 0, 1, 1, 1, 0, 1), ID_TREE = 29338:29345, 
    ID_PLOT = c(1068L, 1068L, 1068L, 1068L, 1068L, 1068L, 1068L, 
    1068L), ID_CATEGORY = c(3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L), 
    ID_WOOD_SPGR_GREENVOL_DRYWT = c(28L, 28L, 28L, 7L, 28L, 28L, 
    28L, 28L), ID_BARK_SPGR_GREENVOL_DRYWT = c(25L, 25L, 25L, 
    18L, 25L, 25L, 25L, 25L), ID_BARK_VOL_PCT = c(2L, 2L, 2L, 
    10L, 2L, 2L, 2L, 2L), VOLCFGRS = c(-2.32258333333333, 5.81718680555556, 
    12.2406407654729, -32.9676545519935, -27.9506018960536, -38.5047101237694, 
    13.6662694477056, 1.9138577595677)), row.names = c(NA, -8L
), class = c("data.table", "data.frame"), .internal.selfref = <pointer: (nil)>)

So far I have gotten the following line of code to work for 1 column:

df1[df1$compare==0,8]<- df2[df1$compare==0,8]

but when I try to abstract it to work for any number of columns I get an error:

df1[df1$compare==0,-(1:7)]<- df2[df1$compare==0,-(1:7)]

I also this and got a similar error:

df1[,-(1:7)]<- ifelse(df1$compare==0, df2[,-(1:7)], df1[,-(1:7)])

the two dataframes will always have the same number of columns.

Answer 1

Most simply you can "invert" your subsetting:

df1[df1$compare==0,8:ncol(df1)] <- df2[df1$compare==0,8:ncol(df1)]

Another option would be to rbind the dijointed rows together.

rbind(df1[df1$compare!=0], df2[df1$compare==0])