How to drop columns by name pattern in R?

Question

I have this dataframe:

state county city  region  mmatrix  X1 X2 X3    A1     A2     A3      B1     B2     B3      C1      C2      C3

  1      1     1      1     111010   1  0  0     2     20    200       Push      8     12      NA      NA      NA
  1      2     1      1     111010   1  0  0     4     NA    400       Shove      9     NA 

Now I want to exclude columns whose names end with a certain string, say "1" (i.e. A1 and B1). I wrote this code:

df_redacted <- df[, -grep("\1$", colnames(df))]

However, this seems to delete every column. How can I modify the code so that it only deletes the columns that matches the pattern (i.e. ends with "3" or any other string)?

The solution has to be able to handle a dataframe with has both numerical and categorical values.

Answer 1

I found a simple answer using dplyr/tidyverse. If your colnames contain "This", then all variables containing "This" will be dropped.

library(dplyr) 
df_new <- df %>% select(-contains("This"))