Select multiple columns with dplyr::select() with numbers as names
Column names starting with a number, such as "1" and "8" in your data, are not syntactically valid names (see ?make.names). Then see the 'Names and Identifiers' section in ?Quoutes: "other [syntactically invalid] names can be used provided they are quoted. The preferred quote is the backtick".
Thus, wrap the invalid column names in backticks (`):
dd %>% dplyr::select(a:f, `1`:`8`)# a a2 b b2 f 1 4 8# 1 0.2510023 0.4109819 0.6787226 0.4974859 0.01828614 0.7449878 0.1648462 0.5875638Another option is to use the SE-version of select, select_:
dd %>% dplyr::select_(.dots = c("a", "a2", ..., "1", "4", "8"))
We can select columns a:f, and add index of numeric columns by converting colnames to numeric:
dd %>% select(a:f, which(!is.na(as.numeric(colnames(dd)))))