Question

我无法理解这个R代码有什么问题，我有几行和col有一个测量或NA我基本上想要得到每行中的最小值和最大值看几个cols：

require(plyr)

census <- read.csv("sps_census.csv")
info <- read.csv("sps_info.csv")


for (i in 1: nrow(census)) {
  trans <- census[i,c("dbh1","dbh2","dbh3","dbh4","dbh5","dbh6","dbh7","dbh8", "dbh9")]
  index.1 <- which (trans != "NA") #some NAs are in the data
  census$min.dbh <- min(trans[1,index.1])
  census$min.dbh.index <- min(index.1)
  census$max.dbh <- max(trans[1,index.1])
  census$max.dbh.index  <- max(index.1)
}

Answer 1

在这一行（和其他三个相似的行）中：

census$min.dbh <- min(trans[1,index.1])

您要将整个列分配给所有相同的值。显然不是你想要的。

也许你想要这样的东西：

census$min.dbh[i] <- min(trans[1,index.1])

请注意，您可以使用apply执行此类操作。如果您提供示例数据（即，使您的问题成为可重现的示例），那么某人编写一个有效的apply示例会容易得多。

Answer 2

您可以使用apply：

index <- c"dbh1","dbh2","dbh3","dbh4","dbh5","dbh6","dbh7","dbh8", "dbh9") #or paste("dbh",1:9,sep="")

census$min.dbh <- apply(census[index], 1, min, na.rm=T)
census$min.db.index <- apply(census[index], 1, function(x){ min(which(!is.na(x))) })
census$max.dbh <- apply(census[index], 1, max, na.rm=T)
census$max.db.index <- apply(census[index], 1, function(x){ max(which(!is.na(x))) })

请注意，我使用is.na(x)代替x != "NA"。

这个循环有什么问题？

2 个答案: