General
PromptBeginner5 minmarkdown
- `sapply` can return a vector
matrix
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General
PromptBeginner5 minmarkdown
- Factors
raw vectors
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Data
PromptBeginner5 minmarkdown
- `subset` argument uses **non-standard evaluation** — column names are resolved in the data frame
which can silently pick up wrong variables in programmatic use. Use `[` with explicit logic in functions.
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Data
PromptBeginner5 minmarkdown
- On a **data frame**
`apply` coerces to matrix via `as.matrix` first — mixed types become character.
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Data
PromptBeginner5 minmarkdown
- Data frame `[` with single column: `df[
1]` returns a **vector** (drop=TRUE default for columns)
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Data
PromptBeginner5 minmarkdown
- Matrix indexing a data frame (`df[cbind(i
j)]`) coerces to matrix first — avoid.
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Coding & Debugging
PromptBeginner5 minmarkdown
- Factor indexing: `x[f]` uses integer codes of factor `f`
not its character labels. Use `x[as.character(f)]` for label-based indexing.
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General
PromptBeginner5 minmarkdown
> Non-obvious behaviors
gotchas
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General
PromptBeginner5 minmarkdown
- `m[j = 2
i = 1]` is `m[2
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General
PromptBeginner5 minmarkdown
- `stl` result components: `$time.series` matrix with columns `seasonal`
`trend`
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General
PromptBeginner5 minmarkdown
- `stl` requires `s.window` (seasonal window) — must be specified
no default. `s.window = periodic` assumes fixed seasonality.
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General
PromptBeginner5 minmarkdown
- `decompose`: simpler than `stl`
uses moving averages. `type = additive` or `multiplicative`.
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General
PromptBeginner5 minmarkdown
- `arima(x
order = c(p
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General
PromptBeginner5 minmarkdown
- `format(object.size(x)
units = MB)` for human-readable output.
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Data
PromptBeginner5 minmarkdown
- `ts(data
start
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General
PromptBeginner5 minmarkdown
- `vignette()` lists all vignettes; `vignette(name
package = pkg)` opens a specific one.
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General
PromptBeginner5 minmarkdown
- Update with `setTxtProgressBar(pb
value)`. Close with `close(pb)`.
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General
PromptBeginner5 minmarkdown
- Style 1: rotating `|/-\`
style 2: simple progress. Only style 3 shows percentage.
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General
PromptBeginner5 minmarkdown
- `txtProgressBar(min
max
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Data
PromptBeginner5 minmarkdown
- `relist(flesh
skeleton)` — `flesh` is the flat data
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General
PromptBeginner5 minmarkdown
- Works with factors
matrices
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General
PromptBeginner5 minmarkdown
- Inverse of `unlist`: given a flat vector and a skeleton list
reconstructs the nested structure.
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General
PromptBeginner5 minmarkdown
- `FUN` argument applies a function to each combination: `combn(5
3
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General
PromptBeginner5 minmarkdown
- **Does** add new names not in `x` — it uses `x[names(val)] <- val` internally
so any name in `val` gets added or replaced.
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