R select all columns matching vector of characters

Question

temp.df <- data.frame(abc_1 = rnorm(10),
                      abc_2 = rnorm(10),
                      abc_3 = rnorm(10),
                      xyz_1 = rnorm(10),
                      xyz_2 = rnorm(10),
                      xyz_3 = rnorm(10),
                      efg_1 = rnorm(10),
                      efg_2 = rnorm(10),
                      efg_3 = rnorm(10),
                      ID_1 = 12,
                      ID_2 = 121,
                      admin = 'a')

If I want to select a particular column with a matching string for eg abc , I would do this

temp.df %>% dplyr::select(names(temp.df)[grepl('abc', names(temp.df))])

However, what I want to do is to select all the columns which has any of the matching string defined in a vector

col.names <- c('abc', 'xyz', 'efg')

ie select columns that has either abc or xyz or efg in the column name

Answer 1

We can use matches

library(dplyr)
library(stringr)
temp.df %>%
          select(matches(str_c(col.names, collapse="|")))
# abc_1        abc_2      abc_3      xyz_1       xyz_2      xyz_3      efg_1      efg_2      efg_3
#1   0.1025701  0.038799612  0.2143873  0.5337834  1.59438881 -1.0237330  1.3720176 -0.8231706  2.4193997
#2  -0.5851774  0.216113597  0.1713179  0.1539639 -1.79143793 -1.0990128 -0.2140094 -0.7128861 -0.5546666
#3   1.4683254 -0.008827679 -0.3650205  0.8683394 -0.77935366 -1.2062593  0.2266538  0.4227441 -0.7425007
#4  -1.6439009  0.750848960 -0.3695533  0.8386111 -0.49404561  1.3429484 -0.5230127  0.4106772 -0.3306021
#5  -0.9025557  1.676054692 -0.2629903 -0.4582141 -1.86148990 -0.7110888 -0.7299364 -0.1007782 -1.0758988
#6  -0.1630221  0.089035672  0.7533968 -1.1604347 -0.02611652  1.8260824 -0.4772013 -0.3414501  2.0913372
#7   0.8977818 -1.558979020  1.5228160  0.7184697 -0.31214593  1.1601056  1.7896162 -1.7205771 -1.8526482
#8   0.5783191 -1.368062940 -0.9343600  1.0642994  0.99022968 -0.3304615 -0.8067144  0.1506883  0.8354455
#9  -0.7315967 -1.476859740 -0.9646872  0.1968119  0.12040511 -1.0855037  1.4778904  1.0592415  2.0147071
#10  0.2532087  0.063369835  0.3045794 -0.9092148  0.50390732  0.6157227  1.0895302 -1.2201279 -0.4196739

Answer 2

You can use col.names in matches :

library(dplyr)
temp.df %>% select(matches(col.names))

#     abc_1  abc_2   abc_3   xyz_1   xyz_2   xyz_3  efg_1   efg_2  efg_3
#1  -0.3262 -0.264 -1.0077  0.3889  0.2485  0.8088  0.499  0.0467 -0.412
#2   0.1485 -0.885  1.2058  0.5115  0.1815  1.7407 -0.474  0.9606 -0.172
#3  -0.3799 -0.500 -0.4928 -0.6404  0.5147 -0.6443  2.594 -0.4211 -0.76
#....

Or using grepl in base R:

temp.df[grepl(paste0(col.names, collapse = "|"), names(temp.df))]