This linter checks for 1:length(...), 1:nrow(...), 1:ncol(...),
1:NROW(...) and 1:NCOL(...) expressions in base-R, or their usage in
conjunction with seq() (e.g., seq(length(...)), seq(nrow(...)), etc.).
Details
Additionally, it checks for 1:n() (from {dplyr}) and 1:.N (from {data.table}).
These often cause bugs when the right-hand side is zero.
It is safer to use base::seq_len() or base::seq_along() instead.
See also
linters for a complete list of linters available in lintr.
Tags
best_practices, consistency, default, efficiency, robustness
Examples
# will produce lints
lint(
text = "seq(length(x))",
linters = seq_linter()
)
#> ::warning file=<text>,line=1,col=1::file=<text>,line=1,col=1,[seq_linter] seq(length(...)) is likely to be wrong in the empty edge case. Use seq_along(...) instead.
lint(
text = "1:nrow(x)",
linters = seq_linter()
)
#> ::warning file=<text>,line=1,col=1::file=<text>,line=1,col=1,[seq_linter] 1:nrow(...) is likely to be wrong in the empty edge case. Use seq_len(nrow(...)) instead.
lint(
text = "dplyr::mutate(x, .id = 1:n())",
linters = seq_linter()
)
#> ::warning file=<text>,line=1,col=24::file=<text>,line=1,col=24,[seq_linter] 1:n() is likely to be wrong in the empty edge case. Use seq_len(n()) instead.
# okay
lint(
text = "seq_along(x)",
linters = seq_linter()
)
lint(
text = "seq_len(nrow(x))",
linters = seq_linter()
)
lint(
text = "dplyr::mutate(x, .id = seq_len(n()))",
linters = seq_linter()
)