I have following two sample dataframes:
df1 <- data.frame(EVI_GT=c(0.23, 0.54, 0.36, 0.92), EVI_GNT=c(0.33, 0.65, 0.42, 0.73), EVI_GGT=c(0.43, 0.34, 0.22, 0.98))
df2 <- data.frame(T_ET_GT=c(0.56, 0.23, 0.95, 0.82), T_ET_GNT=c(0.10, 0.74, 0.36, 0.35), T_ET_GGT=c(0.52, 0.31, 0.65, 0.58))
I have to extract values from df2 corresponding to min and max of df1 (each row). For example, min (max) value of first row in df1 is 0.23 (0.43) i.e., column 1 (column 3) so the values that should be extracted from df2 will be 0.56 and 0.52 for the first row. Similar for row 2 and so on. Below is my desired output dataframe:
df3 <- data.frame(column1=c(0.56, 0.31, 0.65, 0.35), column2=c(0.52, 0.74, 0.36, 0.58))
How can we get df3 from df2 using conditions on df1?
You can use which.min and which.max to get index of minimum and maximum value respectively. Use apply to perform rowwise operation and subset the data from df2.
data.frame(column1 = df2[cbind(1:nrow(df1), apply(df1, 1, which.min))],
column2 = df2[cbind(1:nrow(df1), apply(df1, 1, which.max))])
# column1 column2
#1 0.56 0.52
#2 0.31 0.74
#3 0.65 0.36
#4 0.35 0.58