Extracting part of names in a vector list-CodePudding

I have the following vector of directories.

c("", "Dia 04", "Dia 04/Basler_2020-11-04 13_08_41.568967_bg", 
"Dia 04/Basler_2020-11-04 13_08_41.568967_frames", "Dia 04/Basler_2020-11-04 13_38_46.380957_bg", 
"Dia 04/Basler_2020-11-04 13_38_46.380957_frames", "Dia 04/Basler_2020-11-04 14_08_51.133352_bg", 
"Dia 04/Basler_2020-11-04 14_08_51.133352_frames", "Dia 04/Basler_2020-11-04 14_38_55.875411_bg", 
"Dia 04/Basler_2020-11-04 14_38_55.875411_frames")

I would like to get the unique names that start after the name "Basler_" until the name "_bg" or "_frames".

I try to use pattern in list.dirs() but wont works list.dirs(path = ".", full.names = F, recursive = TRUE, pattern = '(?<=/Basler_).*(?=_bg)')

output desired:

c("2020-11-04 13_08_41.568967", "2020-11-04 13_38_46.380957", "Basler_2020-11-04 14_08_51.133352", "2020-11-04 14_38_55.875411")

Thanks all

CodePudding user response：

Given this data:

names <- c("", "Dia 04", "Dia 04/Basler_2020-11-04 13_08_41.568967_bg", 
           "Dia 04/Basler_2020-11-04 13_08_41.568967_frames", "Dia 04/Basler_2020-11-04 13_38_46.380957_bg", 
           "Dia 04/Basler_2020-11-04 13_38_46.380957_frames", "Dia 04/Basler_2020-11-04 14_08_51.133352_bg", 
           "Dia 04/Basler_2020-11-04 14_08_51.133352_frames", "Dia 04/Basler_2020-11-04 14_38_55.875411_bg", 
           "Dia 04/Basler_2020-11-04 14_38_55.875411_frames")

You can use str_extract:

base R:

unique(str_extract(names, "(?<=Basler_)[\\d_. -] (?=_bg)"))

tidyverse:

library(tidyverse)
data.frame(names) %>%
  mutate(name_0 = str_extract(names, "(?<=Basler_)[\\d_. -] (?=_bg)")) %>%
  pull(name_0) %>%
  unique(.)
[1] NA                           "2020-11-04 13_08_41.568967" "2020-11-04 13_38_46.380957" "2020-11-04 14_08_51.133352"
[5] "2020-11-04 14_38_55.875411"