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[英]Is there an R function to extract data from a matrix with associated column and row headings?
[英]Extract data from column aggregate function in R
我有一個大型數據庫,使用聚合函數從中提取了數據值(x):
library(plotrix)
aggregate(mydataNC[,c(52)],by=list(patientNC, siteNC, supNC),max)
OUTPUT:
每個(x)值在此數據庫中標題為(dist)的列中都有一個對應的距離值。 提取值dist並將其添加到表中的最簡單方法是什么?
我可能先從merge()開始。 這是一個可復制的小示例,您可以用來查看發生了什么並對其進行修改以使用您的數據:
# generate bogus data and view it
x1 <- rep(c("A", "B", "C"), each = 4)
x2 <- rep(c("E", "E", "F", "F"), times = 3)
y1 <- rnorm(12)
y2 <- rnorm(12)
md <- data.frame(x1, x2, y1, y2)
> head(md)
x1 x2 y1 y2
1 A E -1.4603164 -0.9662473
2 A E -0.5247227 1.7970341
3 A F 0.8990502 1.7596285
4 A F -0.6791145 2.2900357
5 B E 1.2894863 0.1152571
6 B E -0.1981511 0.6388998
# aggregate by taking maximum of each unique (x1, x2) combination
md.agg <- with(md, aggregate(y1, by = list(x1, x2), FUN = max))
names(md.agg) <- c("x1", "x2", "y1")
> md.agg
x1 x2 y1
1 A E -0.5247227
2 B E 1.2894863
3 C E 0.9982510
4 A F 0.8990502
5 B F 2.5125956
6 C F -0.5916491
# merge y2 into the aggregated data
md.final <- merge(md, md.agg)
> md.final
x1 x2 y1 y2
1 A E -0.5247227 1.7970341
2 A F 0.8990502 1.7596285
3 B E 1.2894863 0.1152571
4 B F 2.5125956 -0.2217510
5 C E 0.9982510 0.6813261
6 C F -0.5916491 1.0348518
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