I have a dataframe with only one row. How can I find which column contains the same value as another specified column in the same dataframe?
For example, I want to find which flavour is the favorite flavor in this df. The answer should be the column name flavour2 since it coincides with 'Apple':
df <- data.frame(flavour1 = c("Grape"),
flavour2 = c("Apple"),
flavour3 = c("Strawberry"),
favourite = c("Apple"))
Thank you!
If you want to check which column has the same value as favourite, this might do the trick:
colnames(df)[grep(df$favourite, df[1:3])]
Output:
> colnames(df)[grep(df$favourite, df[1:3])]
[1] "flavour2"
grep(df$favourite, df[1:3]) returns the column index of df[1:3] that matches the value of df$favourite. Then, using this index, colnames(df)[] select the right column name.
You can compare all the values in df with favourite column and return the corresponding column name.
names(which(df$favourite == unlist(df[-ncol(df)])))
#[1] "flavour2"
We can also use
names(df)[df$favourite == df[-length(df)]]
#[1] "flavour2"
Or using match
names(df)[match(df$favourite, unlist(df[-length(df)]))]
#[1] "flavour2"
colnames(df)[grep(df$favourite, df[1:3])]The output:[1] "flavour2"