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> dput(test)
structure(list(MEMORY1 = c(7.5, 6, 6, 3.5, 5, 5), MEMORY2 = c(5,
7.5, 3, 3.5, 5, 5), MEMORY3 = c(5, 3.5, 3, 3.5, 5, 2), MEMORY4 = c(2,
1.5, 3, 3.5, 1, 2), MEMORY5 = c(7.5, 3.5, 3, 3.5, 5, 7), MEMORY6 = c(2,
5, 7.5, 7.5, 5, 5), MEMORY7 = c(2, 1.5, 3, 3.5, 5, 2), MEMORY8 = c(5,
7.5, 7.5, 7.5, 5, 8)), .Names = c("MEMORY1", "MEMORY2", "MEMORY3",
"MEMORY4", "MEMORY5", "MEMORY6", "MEMORY7", "MEMORY8"), row.names = c(NA,
6L), class = "data.frame")
> test
MEMORY1 MEMORY2 MEMORY3 MEMORY4 MEMORY5 MEMORY6 MEMORY7 MEMORY8
1 7.5 5.0 5.0 2.0 7.5 2.0 2.0 5.0
2 6.0 7.5 3.5 1.5 3.5 5.0 1.5 7.5
3 6.0 3.0 3.0 3.0 3.0 7.5 3.0 7.5
4 3.5 3.5 3.5 3.5 3.5 7.5 3.5 7.5
5 5.0 5.0 5.0 1.0 5.0 5.0 5.0 5.0
6 5.0 5.0 2.0 2.0 7.0 5.0 2.0 8.0
I have a data.frame, and I would like to subset just the first row. If I do test[1, ], the result is
> test[1, ]
MEMORY1 MEMORY2 MEMORY3 MEMORY4 MEMORY5 MEMORY6 MEMORY7 MEMORY8
1 7.5 5 5 2 7.5 2 2 5
How do I subset the data.frame so that I get just a vector of the numbers without the column names?
940
The most easiest way to drop columns is by using subset() function. In the code below, we are telling R to drop variables x and z. The '-' sign indicates dropping variables. Make sure the variable names would NOT be specified in quotes when using subset() function.
How to subset the data frame (DataFrame) by column value and name in R? By using R base df[] notation, or subset() you can easily subset the R Data Frame (data. frame) by column value or by column name.
To pick out single or multiple columns use the select() function. The select() function expects a dataframe as it's first input ('argument', in R language), followed by the names of the columns you want to extract with a comma between each name.
What you want is a numeric vector instead of a data.frame. For this, you can just use as.numeric to do the conversion
> as.numeric(df[1,])
[1] 7.5 5.0 5.0 2.0 7.5 2.0 2.0 5.0
You can use unlist with option use.names=FALSE to return only vector without names.
unlist(test[1,], use.names=FALSE)
#[1] 7.5 5.0 5.0 2.0 7.5 2.0 2.0 5.0
test[1,] is still a data.frame with 8 columns. A data.frame can be regarded as a list having the same length for its list elements (or columns). So we can use unlist. This also works when you are creating a vector from more than one row.
unlist(test[1:2,], use.names=FALSE)
Or as @Frank suggested, if we are subsetting multiple rows by keeping the dimensions, we set the names to NULL and convert to matrix.
as.matrix(setNames(test[1:2,],NULL))
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