Convert a row of a data frame to vector

Question

I want to create a vector out of a row of a data frame  But I don t want to have to row and column names  I tried several things    but had no luck   This is my data frame    gt  df  lt - data frame a c 1 2 4 2  b c 2 6 2 1  c c 2 6 8 2 7 5 3    gt  df   a b   c 1 1 2 2 6 2 2 6 8 2 3 4 2 7 5 4 2 1 3 0   I tried    gt  newV  lt - as vector df 1     gt  newV   a b   c 1 1 2 2 6   But I really want something looking like this    gt  newV  lt - c  1 2 2 6   gt  newV  1  1 0 2 0 2 6

User · Accepted Answer

When you extract a single row from a data frame you get a one-row data frame. Convert it to a numeric vector:

as.numeric(df[1,])

As @Roland suggests, unlist(df[1,]) will convert the one-row data frame to a numeric vector without dropping the names. Therefore unname(unlist(df[1,])) is another, slightly more explicit way to get to the same result.

As @Josh comments below, if you have a not-completely-numeric (alphabetic, factor, mixed ...) data frame, you need as.character(df[1,]) instead.

User · Answer

If you don t want to change to numeric you can try this    gt  as vector t df   1    1  1 0 2 0 2 6

User · Answer

Here is a dplyr based option   newV   df   gt   slice 1    gt   unlist use names   FALSE     or slightly different  newV   df   gt   slice 1    gt   unlist     gt   unname

User · Answer

Columns of data frames are already vectors  you just have to pull them out  Note that you place the column you want after the comma  not before it    gt  newV  lt - df  1   gt  newV  1  1 2 4 2   If you actually want a row  then do what Ben said and please use words correctly in the future

User · Answer

Note that you have to be careful if your row contains a factor  Here is an example   df 1   data frame V1   factor 11 15                     V2   21 25  df 1 1     gt   as numeric     you expect 11 21 but it returns   1  1 21   Here is another example  by default data frame   converts characters to factors    df 2   data frame V1   letters 1 5                     V2   1 5  df 2 3     gt   as numeric     you expect to obtain c 3 but it returns  1  3 3 df 2 3     gt   as character     this won t work neither  1   3   3    To prevent this behavior  you need to take care of the factor  before extracting it   df 1 V1   df 1 V1   gt   as character     gt   as numeric   df 2 V1   df 2 V1   gt   as character   df 1 1     gt   as numeric    1  11  21 df 2 3     gt   as character    1   c   3

User · Answer

I recommend unlist  which keeps the names   unlist df 1      a   b   c  1 0 2 0 2 6   is vector unlist df 1      1  TRUE   If you don t want a named vector   unname unlist df 1      1  1 0 2 0 2 6

[r] Convert a row of a data frame to vector

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