R：拆分数据帧列中的字符串

我有一个数据框，其中一列包含字符串。我想把这些字符串分开，用一个点隔开，并始终保留第一部分

这将是我的数据帧：

                                             State
1             This is my string. I do not want this
2   This is other string. I do not want this either

我想得到这个：

                   State
1      This is my string
2   This is other string

我已经试过了，但现在可以用了：

df = df >%> dplyr::mutate(State= str_split(State,".")[1])

这是否有效：

library(dplyr)
library(stringr)
df
                                            State
1           This is my string. I do not want this
2 This is other string. I do not want this either
df %>% mutate(State = str_remove(State, '\\..*'))
                 State
1    This is my string
2 This is other string