General
PromptBeginner5 minmarkdown
- `which = both` (default)
`left`
0
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119,274 skills indexed with the new KISS metadata standard.
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General
PromptBeginner5 minmarkdown
- Assignment form: `substr(x
1
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General
PromptBeginner5 minmarkdown
- `substring(x
first
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General
PromptBeginner5 minmarkdown
- Common mistake: unnamed arguments silently match `fixed`
`perl`
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General
PromptBeginner5 minmarkdown
- Returns a **list** (one element per input string)
even for a single string.
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General
PromptBeginner5 minmarkdown
- Three regex modes: POSIX extended (default)
`perl = TRUE`
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General
PromptBeginner5 minmarkdown
- **Name arguments explicitly** — unnamed args after `x`/`pattern` are matched positionally to `ignore.case`
`perl`
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General
PromptBeginner5 minmarkdown
- `read.csv` defaults differ from `read.table`: `header = TRUE`
`sep =
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General
PromptBeginner5 minmarkdown
- `sep = "` (default) means **any whitespace** (spaces
tabs
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General
PromptBeginner5 minmarkdown
- `file_test(-nt
f1
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General
PromptBeginner5 minmarkdown
- `file_test(-d
path)`: TRUE if directory exists.
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General
PromptBeginner5 minmarkdown
> Non-obvious behaviors
gotchas
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General
PromptBeginner5 minmarkdown
- `file_test(-f
path)`: TRUE if regular file exists.
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General
PromptBeginner5 minmarkdown
- On some filesystems
`ctime` is status-change time
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Data
PromptBeginner5 minmarkdown
- Returns data frame with `size`
`isdir`
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General
PromptBeginner5 minmarkdown
- `list.files(pattern = *.csv)` — `pattern` is a **regex**
not a glob! Use `glob2rx(*.csv)` or `\\.csv$`.
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General
PromptBeginner5 minmarkdown
- `file.path(a
b
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General
PromptBeginner5 minmarkdown
- `options(contrasts = c(contr.treatment
contr.poly))`: default contrasts for unordered/ordered factors.
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General
PromptBeginner5 minmarkdown
- `options(warn = n)`: -1 = ignore warnings
0 = collect (default)
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General
PromptBeginner5 minmarkdown
- `options(OutDec =
)`: change decimal separator in output (affects `format`
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General
PromptBeginner5 minmarkdown
- `options(digits.secs = n)`: max decimal digits for seconds in time formatting (0-6
default 0).
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General
PromptBeginner5 minmarkdown
- `options(digits = n)`: significant digits for printing (1-22
default 7). Suggestion only.
0
General
PromptBeginner5 minmarkdown
- `options(scipen = n)`: positive biases toward fixed notation
negative toward scientific. Default 0. Applies to `print`/`format`/`cat` but not `sprintf`.
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General
PromptBeginner5 minmarkdown
- `system.time(expr)` returns `user`
`system`
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