Fix lintrs, no group_by issues #1320

Job	Run time
R-CMD-check / macOS-latest (release)	8m 6s
R-CMD-check / windows-latest (devel)	22m 1s
R-CMD-check / windows-latest (release)	19m 54s
R-CMD-check / windows-latest (oldrel)	21m 38s
R-CMD-check / windows-latest (4.1)	4m 58s
R-CMD-check / ubuntu-latest (devel)	18m 33s
R-CMD-check / ubuntu-latest (release)	16m 44s
R-CMD-check / ubuntu-latest (4.3)	13m 54s
R-CMD-check / ubuntu-latest (4.2)	52s
R-CMD-check / ubuntu-latest (4.1)	1m 10s
R-CMD-check / ubuntu-latest (4.0)	50s
	2h 8m 40s

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