Hi James,
I don't know how to solve it with "tapply" (something with split I
think..), but you could use "plyr" (from Hadley Wickham).
library(plyr)
# Generate some data
set.seed(321)
myD <- data.frame(
Place = sample(c("AWQ","DFR", "WEQ"), 10, replace=T),
Light = sample(LETTERS[1:2], 15, replace=T),
value=rnorm(30)
)
myD[c(3,12,29), "value"] <- NA
# data.frame to data.frame
ddply(myD, .(Place, Light), summarise,
quan_value = quantile(value, na.rm=TRUE))
# data.frame to list
quant <- function(df) quantile(df$value, na.rm=TRUE)
dlply(myD, .(Place, Light), quant)
Cheers
Patrick
Am 09.04.2010 03:24, schrieb James Rome:
I am trying to calculate quantiles of a data frame column split up by
two factors:
# Calculate the quantiles
quarts = tapply(gdf$tt, list(gdf$Runway, gdf$OnHour), FUN=quantile,
na.rm = TRUE)
This does not work:
quarts
04L 04R 15R 22L 22R 27 32
33L 33R
0 NULL Numeric,5 NULL Numeric,5 NULL Numeric,5 NULL
Numeric,5 NULL
1 NULL Numeric,5 NULL Numeric,5 NULL NULL NULL
Numeric,5 NULL
2 NULL NULL NULL Numeric,5 NULL NULL NULL
NULL NULL
3 NULL NULL NULL NULL NULL NULL NULL
Numeric,5 NULL
4 NULL NULL NULL NULL NULL NULL NULL
NULL NULL
5 NULL NULL NULL NULL NULL NULL NULL
NULL NULL
6 NULL NULL NULL NULL NULL NULL NULL
NULL NULL
7 NULL Numeric,5 NULL NULL NULL Numeric,5 NULL
Numeric,5 NULL
8 NULL Numeric,5 NULL Numeric,5 NULL Numeric,5 NULL
Numeric,5 NULL
. . .
But if I leave out either of the two factors, it does work
quarts = tapply(gdf$tt, list(gdf$Runway), FUN=quantile, na.rm = TRUE)
quarts
$`04L`
0% 25% 50% 75% 100%
4 8 9 10 20
$`04R`
0% 25% 50% 75% 100%
0 9 10 11 28
. . . .
How can I get this to work?
Thanks,
Jim Rome
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