Description Usage Arguments Details Author(s) See Also Examples
Return the data.table with only the non-key columns.
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dt |
A data.table with (or without) a key |
usestrings |
TRUE or FALSE - If performance is poor with usestrings = TRUE, then try setting usestrings = FALSE |
Uses .SD and .SDcol to do the subsetting (by default). This can be slow, so there is also an option to use the strings to subset the the columns.
Gene Leynes
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | dt_longley <- data.table(year = as.integer(rownames(longley)),
GNP = longley$GNP,
Unemployed = longley$Unemployed)
dt_sunspots <- data.table(year = as.integer(time(sunspot.year)),
sunspots = as.integer(sunspot.year),
key = "year")
dt_model <- dt_sunspots[dt_longley]
## We don't want to regress on the key "year"!
summary(lm(GNP~., dt_model))$coef
# Estimate Std. Error t value Pr(>|t|)
# (Intercept) -4.320245e+04 845.45463019 -51.09966406 2.071517e-15
# year 2.232154e+01 0.43481740 51.33542936 1.960650e-15
# sunspots 2.491893e-03 0.02519022 0.09892303 9.228327e-01
# Unemployed -1.175555e-01 0.02253020 -5.21768359 2.155365e-04
## This makes more sense:
summary(lm(GNP~., nokey(dt_model)))$coef
# Estimate Std. Error t value Pr(>|t|)
# (Intercept) 198.4062549 78.6665975 2.5221156 0.02550192
# sunspots -0.2825965 0.3506266 -0.8059756 0.43475304
# Unemployed 0.6776781 0.2334579 2.9027853 0.01234176
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