関連ワード:  create empty dataframe with columns r    create empty dataframe with x columns r    create empty dataframe with two columns r    create empty dataframe with named columns r    create empty data frame with column names r    create empty dataframe with column and row names    make empty dataframe with column names r    initialize empty dataframe with column names r    define empty dataframe with column names r    create empty dataframe with column names and append rows  
結果 : create empty dataframe with columns r