下面应该让你开始。你基本上需要做两件事:子集和聚合。我将演示一个基本的R解决方案和一个data.table
解决方案。
首先,一些样本数据。
set.seed(1) # So you can reproduce my results
dat <- data.frame(KeyItem = rep(c("Pretax", "TotalAssets", "TotalLiabilities"),
times = 30),
Bank = rep(c("WellsFargo", "BankOfAmerica", "ICICI"),
each = 30),
Country = rep(c("UnitedStates", "India"), times = c(60, 30)),
Year = rep(c(2000:2009), each = 3, times = 3),
Value = runif(90, min=300, max=600))
让我们从“国家”和“年”“税前”值的总平均值,但只适用于2001年至2005年
aggregate(Value ~ Country + Year,
dat[dat$KeyItem == "Pretax" & dat$Year >= 2001 & dat$Year <=2005, ],
mean)
# Country Year Value
# 1 India 2001 399.7184
# 2 UnitedStates 2001 464.1638
# 3 India 2002 443.5636
# 4 UnitedStates 2002 560.8373
# 5 India 2003 562.5964
# 6 UnitedStates 2003 370.9591
# 7 India 2004 404.0050
# 8 UnitedStates 2004 520.4933
# 9 India 2005 567.6595
# 10 UnitedStates 2005 493.0583
下面是data.table
同样的事情
library(data.table)
DT <- data.table(dat, key = "Country,Bank,Year")
subset(DT, KeyItem == "Pretax")[Year %between% c(2001, 2005),
mean(Value), by = list(Country, Year)]
# Country Year V1
# 1: India 2001 399.7184
# 2: India 2002 443.5636
# 3: India 2003 562.5964
# 4: India 2004 404.0050
# 5: India 2005 567.6595
# 6: UnitedStates 2001 464.1638
# 7: UnitedStates 2002 560.8373
# 8: UnitedStates 2003 370.9591
# 9: UnitedStates 2004 520.4933
# 10: UnitedStates 2005 493.0583
欢迎来到SO,这个问题在此之前已经被询问了很多次。尝试http://stackoverflow.com/questions/8225621/faster-way-to-create-variable-that-aggregates-a-column-by-id例如 – mnel
欢迎来到SO。 @mnel是正确的 - 关于聚合的问题已经在这里多次提出。对于您的问题,您必须同时汇总和分类您的数据。您可以稍后汇总第一个和子集,或者,如果您的数据集非常大,则先选择子集,然后汇总(这是我在答案中演示的内容,但不是那么喜欢通过实验远离您学习的乐趣)。此外,作为您的必读书籍,这里的大多数用户通常会对[可重现的示例]做出更快速的响应(http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example)。 – A5C1D2H2I1M1N2O1R2T1