I am using a loop to rename columns using cbind. Every time I attempt to name the column using the loop indices (i), it does not use the indices and instead puts in i for the column names. I want it to display the actual names from the original
x <- seq(0, 50, by = 1)
y <- seq(50, 100, by = 1)
z <- seq(25, 75, by = 1)
df <- data.frame(cbind(x, y, z))
df_final <- NULL
for (i in colnames(df)){
#PROBLEM: Column names becomes i instead of the actual column names
df_final <- cbind(df_final, i = df[,i])
}
df_final
A simple solution will be to set the colname in the loop like:
df_final <- NULL
for (i in colnames(df)){
df_final <- cbind(df_final, df[,i])
colnames(df_final)[ncol(df_final)] <- i
}
colnames(df_final)
#[1] "x" "y" "z"
str(df_final)
# num [1:51, 1:3] 0 1 2 3 4 5 6 7 8 9 ...
# - attr(*, "dimnames")=List of 2
# ..$ : NULL
# ..$ : chr [1:3] "x" "y" "z"
For using the method x[[i]] <- value, x need to have rows:
df_final <- data.frame()[seq_len(nrow(df)),0] #Create empty data frame with rows
for (i in colnames(df)){
df_final[[i]] <- df[,i]
}
colnames(df_final)
#[1] "x" "y" "z"
str(df_final)
#'data.frame': 51 obs. of 3 variables:
# $ x: num 0 1 2 3 4 5 6 7 8 9 ...
# $ y: num 50 51 52 53 54 55 56 57 58 59 ...
# $ z: num 25 26 27 28 29 30 31 32 33 34 ...
otherwise it will create a list, which could be converted to a data.frame with list2DF.
df_final <- NULL
for (i in colnames(df)){
df_final[[i]] <- df[,i]
}
colnames(df_final)
#NULL
str(df_final)
#List of 3
# $ x: num [1:51] 0 1 2 3 4 5 6 7 8 9 ...
# $ y: num [1:51] 50 51 52 53 54 55 56 57 58 59 ...
# $ z: num [1:51] 25 26 27 28 29 30 31 32 33 34 ...
df_final <- list2DF(df_final)
colnames(df_final)
#[1] "x" "y" "z"
str(df_final)
#'data.frame': 51 obs. of 3 variables:
# $ x: num 0 1 2 3 4 5 6 7 8 9 ...
# $ y: num 50 51 52 53 54 55 56 57 58 59 ...
# $ z: num 25 26 27 28 29 30 31 32 33 34 ...
When the loop is done with sapply instead of for a solution would be:
df_final <- sapply(colnames(df), function(i) {df[,i]})
colnames(df_final)
#[1] "x" "y" "z"
str(df_final)
# num [1:51, 1:3] 0 1 2 3 4 5 6 7 8 9 ...
# - attr(*, "dimnames")=List of 2
# ..$ : NULL
# ..$ : chr [1:3] "x" "y" "z"
as.data.frame.matrix(df_final) # Convert it to data.frame
Or simply subsetting:
df_final <- df[colnames(df)]
colnames(df_final)
#[1] "x" "y" "z"
str(df_final)
#'data.frame': 51 obs. of 3 variables:
# $ x: num 0 1 2 3 4 5 6 7 8 9 ...
# $ y: num 50 51 52 53 54 55 56 57 58 59 ...
# $ z: num 25 26 27 28 29 30 31 32 33 34 ...