r - 动物园中的基本条件数据选择

Question

我有一个动物园“z”。有人可以解释一下为什么加载动物园库后我的请求which(z[2,]>0 & z[1,]>0)不再起作用吗？

> str(z)
 zoo [1:2, 1:12] 0 0 0 0 0 0 0 0 0 0 ...
 - attr(*, "dimnames")=List of 2
  ..$ : NULL
  ..$ : NULL
 - attr(*, "index")=Classes 'dates', 'times'  atomic [1:2] 17531 17562
  .. ..- attr(*, "format")= chr "m/d/y"
  .. ..- attr(*, "origin")= Named num [1:3] 1 1 1970
  .. .. ..- attr(*, "names")= chr [1:3] "month" "day" "year"

> which(z[2,]>0 & z[1,]>0)
[1] 12

> library(zoo)

Attaching package: ‘zoo’

The following objects are masked from ‘package:base’:

    as.Date, as.Date.numeric


> which(z[2,]>0 & z[1,]>0)
integer(0)

对于那些感兴趣的人：

> dput(z)
structure(c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
0, 0, 0, 0, 0, 0.00996714478550151, 0.00996009385006366), .Dim = c(2L, 
12L), .Dimnames = list(NULL, NULL), index = structure(c(17531, 
17562), format = "m/d/y", origin = structure(c(1, 1, 1970), .Names = c("month", 
"day", "year")), class = c("dates", "times")), class = "zoo")

Answer 1

它将尝试合并 z[1, ] 和 z[2, ] 以执行 & 但它们没有共同点。

您可以尝试以下方法之一：

library(zoo)

## 1
which(apply(z > 0, 2, all))

## 2 
which(pmin(z[1, ], z[2, ]) > 0)

## 3
which(colSums(z > 0) == nrow(z))

## 4
which(apply(z, 2, min) > 0)

## 5
cz <- coredata(z)
which(cz[1, ] > 0 & cz[2, ] > 0)

# 6
library(matrixStats)
which(colAlls(z > 0))