根据一列选择数据集的子集

Question

I have a dataset with 2 columns

                           text  created
    1                   cant do it with cards either 1/2/2014
    2                   cant do it with cards either 2/2/2014
    3                            Coming back home AK 2/2/2014
    4                            Coming back home AK 5/2/2014
    5                                 gotta try PNNL 1/2/2014
    6 Me and my Tart would love to flyLoveisintheAir 5/2/2014
    7 Me and my Tart would love to flyLoveisintheAir 6/2/2014

How can I get subset the dataset, based on the unique string of first column?

                           text  created
    1                   cant do it with cards either 1/2/2014
    3                            Coming back home AK 2/2/2014
    5                                 gotta try PNNL 1/2/2014
    6 Me and my Tart would love to flyLoveisintheAir 5/2/2014


structure(list(text = structure(c(1L, 1L, 2L, 2L, 3L, 4L, 4L), .Label = c("cant do it with cards either", 
"Coming back home AK", "gotta try PNNL", "Me and my Tart would love to flyLoveisintheAir"
), class = "factor"), created = structure(c(1L, 2L, 2L, 3L, 1L, 
3L, 4L), .Label = c("1/2/2014", "2/2/2014", "5/2/2014", "6/2/2014"
), class = "factor")), .Names = c("text", "created"), class = "data.frame", row.names =  c(NA, 
-7L))

Answer 1

Try using duplicated and ! . Consider df is your data.frame.

> df[!duplicated(df$text), ]
                                            text  created
1                   cant do it with cards either 1/2/2014
3                            Coming back home AK 2/2/2014
5                                 gotta try PNNL 1/2/2014
6 Me and my Tart would love to flyLoveisintheAir 5/2/2014

Answer 2

there is a lot of possibilities:

tab[!duplicated(tab$text),]
# with dplyr
filter(tab, !duplicated(text))

hth