Data
PromptBeginner5 minmarkdownQuality: 22
- rbind on data frames matches columns by name
not position. Missing columns get NA.
0
Explore
Find agent skills by outcome
17,478 skills indexed with the new KISS metadata standard.
Showing 24 of 17,478Categories: Data, Cursor-rules, Coding & Debugging, Education
Data
PromptBeginner5 minmarkdownQuality: 26
- cbind on data frames calls data.frame(...)
not cbind.matrix. Mixing matrices and data frames can give unexpected results.
0
Data
PromptBeginner5 minmarkdownQuality: 26
- Default by is `intersect(names(x)
names(y))` — can silently merge on unintended columns if data frames share column names.
0
Data
PromptBeginner5 minmarkdownQuality: 26
- Returns an array (not a data frame). Class info on return values is discarded (e.g.
Date objects become numeric).
0
Data
PromptBeginner5 minmarkdownQuality: 26
- On a data frame
apply coerces to matrix via as.matrix first — mixed types become character.
0
Data
PromptBeginner5 minmarkdownQuality: 26
- 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.
0
Data
PromptBeginner5 minmarkdownQuality: 22
- Matrix indexing a data frame (`df[cbind(i
j)]`) coerces to matrix first — avoid.
0
Data
PromptBeginner5 minmarkdownQuality: 26
- Data frame [ with single column: `df[
1]` returns a vector (drop=TRUE default for columns)
0
Coding & Debugging
PromptBeginner5 minmarkdownQuality: 26
- Factor indexing: x[f] uses integer codes of factor f
not its character labels. Use x[as.character(f)] for label-based indexing.
0
Data
PromptBeginner5 minmarkdownQuality: 22
- `ts(data
start
0
Data
PromptBeginner5 minmarkdownQuality: 22
- `relist(flesh
skeleton) — flesh` is the flat data
0
Data
PromptBeginner5 minmarkdownQuality: 22
- Useful pattern: `do.call(rbind
listofdfs)` to combine a list of data frames.
0
Data
PromptBeginner5 minmarkdownQuality: 26
- io-and-text.md — Read when: read.table silently drops data or misparses columns
regex behaves differently than expected
0
Data
PromptBeginner5 minmarkdownQuality: 26
- visualization.md — Read when: par settings reset unexpectedly
layout/mfrow interaction is confusing
0
Data
PromptBeginner5 minmarkdownQuality: 26
- statistics.md — Read when: hypothesis test gives surprising result
need to choose correct p.adjust method
0
Data
PromptBeginner5 minmarkdownQuality: 26
- data-wrangling.md — Read when: subsetting returns wrong type
apply on data frame gives unexpected coercion
0
Data
PromptBeginner5 minmarkdownQuality: 22
fit <- aov(value ~ group
data = df)
0
Data
PromptBeginner5 minmarkdownQuality: 22
fit <- lm(y ~ x1 + x2
data = df)
0
Data
PromptBeginner5 minmarkdownQuality: 22
predict(fit
newdata = new_df)
0
Data
PromptBeginner5 minmarkdownQuality: 22
boxplot(value ~ group
data = df
0
Data
PromptBeginner5 minmarkdownQuality: 22
saveRDS(obj
data.rds)
0
Data
PromptBeginner5 minmarkdownQuality: 22
df <- read.table(data.txt
header = TRUE
0
Data
PromptBeginner5 minmarkdownQuality: 22
df <- read.csv(data.csv
stringsAsFactors = FALSE)
0
Data
PromptBeginner5 minmarkdownQuality: 22
aggregate(value ~ group
data = df
0