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我正在使用:Ubuntu 12.04 64 位、R 3.0.2、RStudio 0.98.312、knitr 1.5、markdown 0.6.3、mgcv1.​​7-27

我有一个包含多个代码块的 Rmarkdown 文档。在一个块的中间有一些代码,我适合 GAM,总结适合度并绘制适合度。问题是第一个图渲染到输出文件中,但第二个图没有。这是来自该块的经过清理的代码片段:

fit <- gam(y ~ s(x), data=j0, subset= !is.na(x))
summary(fit) # look at non-missing only
plot(fit)

fit <- gam(y ~ s(sqrt(x)), data=j0, subset= !is.na(x))
summary(fit)
plot(fit)

mean(y[is.na(x)]) - mean(y[!is.na(x)])

一切都按预期呈现,除了输出直接从回显第二个绘图语句到回显下面的均值计算。均值计算的结果正确呈现。

如果我稍后在块中注释掉另一个绘图调用 7 行,则丢失的绘图将正确呈现。

有人对这里发生的事情有任何建议吗?

下面更新

总结 - 在调用 Plot 2 之后的几行,有一些 R 代码会生成执行错误(未找到变量),之后几行调用 Plot 3。如果代码错误得到修复,则渲染 Plot 2。如果代码错误未修复并且对 Plot 3 的调用被注释掉,则渲染 Plot 2。问题取决于用于存储不同拟合结果的相同变量“拟合”。如果我将每个拟合分配给不同的变量 Plot 2 呈现 OK。

我不明白在成功执行多行代码后所做的更改如何(显然是回顾性地)阻止 Plot 2 呈现。

可重现的例子:

Some text.

```{r setup}
require(mgcv)

mkdata <- function(n=100) {
  x <- rnorm(n) + 5
  y <- x + 0.3 * rnorm(n)
  x[sample(ceiling(n/2), ceiling(n/10))] <- NA
  x <- x^2
  data.frame(x, y)  
} 
```

Example 1
=========

Plot 2 fails to render. (Using the same fit object for each fit.)

```{r example_1}
j0 <- mkdata()
attach(j0)
mx <- min(x, na.rm=TRUE)

fit <- gam(y ~ s(x), data=j0, subset= !is.na(x))
summary(fit)
plot(fit) # plot 1

fit <- gam(y ~ s(sqrt(x)), data=j0, subset= !is.na(x))
summary(fit)
plot(fit) #plot 2

mean(y[is.na(x)]) - mean(y[!is.na(x)]) # means calculation

# recode the missing values
j0$x.na <- is.na(x)
j0$x.c <- ifelse(x.na, mx, x) # ERROR in recode
detach()

attach(j0)
fit <- gam(y ~ s(sqrt(x.c)) + x.na, data=j0) # doesn't run because of error in recode
summary(fit) # this is actually fit 2
plot(fit) # plot 3 (this is actually fit 2)
detach()
```

Example 2
=========

Use separate fit objects for each fit. Plot 2 renders OK.

```{r example_2}
j0 <- mkdata()
attach(j0)
mx <- min(x, na.rm=TRUE)

fit1 <- gam(y ~ s(x), data=j0, subset= !is.na(x))
summary(fit1)
plot(fit1) # plot 1

fit2 <- gam(y ~ s(sqrt(x)), data=j0, subset= !is.na(x))
summary(fit2)
plot(fit2) #plot 2

mean(y[is.na(x)]) - mean(y[!is.na(x)]) # means calculation

# recode the missing values
j0$x.na <- is.na(x)
j0$x.c <- ifelse(x.na, mx, x) # ERROR in recode
detach()

attach(j0)
fit3 <- gam(y ~ s(sqrt(x.c)) + x.na, data=j0) # doesn't run because of error in recode
summary(fit3)
plot(fit3) # plot 3
detach()
```

Example 3
=========

Revert to using the same fit object for each fit. Plot 2 renders because plot 3 is commented out.

```{r example_3}
j0 <- mkdata()
attach(j0)
mx <- min(x, na.rm=TRUE)

fit <- gam(y ~ s(x), data=j0, subset= !is.na(x))
summary(fit)
plot(fit) # plot 1

fit <- gam(y ~ s(sqrt(x)), data=j0, subset= !is.na(x))
summary(fit)
plot(fit) #plot 2

mean(y[is.na(x)]) - mean(y[!is.na(x)]) # means calculation

# recode the missing values
j0$x.na <- is.na(x)
j0$x.c <- ifelse(x.na, mx, x) # ERROR in recode
detach()

attach(j0)
fit <- gam(y ~ s(sqrt(x.c)) + x.na, data=j0)
summary(fit) # this is actually fit 2
# plot(fit) # plot 3 (this is actually fit 2)
detach()
```

Example 4
=========

Plot 2 renders because later recode error is fixed.

```{r example_4}
j0 <- mkdata()
attach(j0)
mx <- min(x, na.rm=TRUE)

fit <- gam(y ~ s(x), data=j0, subset= !is.na(x))
summary(fit)
plot(fit) # plot 1

fit <- gam(y ~ s(sqrt(x)), data=j0, subset= !is.na(x))
summary(fit)
plot(fit) #plot 2

mean(y[is.na(x)]) - mean(y[!is.na(x)]) # means calculation

# recode the missing values
j0$x.na <- is.na(x)
j0$x.c <- ifelse(j0$x.na, mx, x) # error in recode fixed
detach()

attach(j0)
fit <- gam(y ~ s(sqrt(x.c)) + x.na, data=j0)
summary(fit)
plot(fit) # plot 3
detach()
```

日志文件:

> require(knitr); knit('reproduce.Rmd', encoding='UTF-8');
Loading required package: knitr


processing file: reproduce.Rmd
  |......                                                           |   9%
  ordinary text without R code

  |............                                                     |  18%
label: setup
  |..................                                               |  27%
  ordinary text without R code

  |........................                                         |  36%
label: example_1
  |..............................                                   |  45%
  ordinary text without R code

  |...................................                              |  55%
label: example_2
  |.........................................                        |  64%
  ordinary text without R code

  |...............................................                  |  73%
label: example_3
  |.....................................................            |  82%
  ordinary text without R code

  |...........................................................      |  91%
label: example_4
  |.................................................................| 100%
  ordinary text without R code


output file: reproduce.md

[1] "reproduce.md"
4

1 回答 1

9

你只是另一个受害者attach(),尽管人们一直在警告不要使用attach(). 太容易搞砸了attach()。你在你之后做了这个attach(j0)

j0$x.na <- is.na(x)
j0$x.c <- ifelse(x.na, mx, x) # ERROR in recode

当然,R 找不到对象x.na,因为它在任何地方都不存在。是的,它现在就在其中,但除非您分离并重新连接它,j0否则它不会暴露给 R。j0换句话说,attach()当您将更多变量添加到j0. 所以简单的解决方法是:

j0$x.c <- ifelse(j0$x.na, mx, x)

我理解你为什么要使用attach()——你可以在任何地方避免尴尬的j0$前缀,但你需要非常小心。除了我提到的问题,detach()也不好,因为你没有指定要分离哪个环境,默认情况下,搜索路径上的第二个是分离的,不一定是你附加的那个,例如你可能已经加载了其他包进入搜索路径。因此,您必须明确:detach('j0').

回到knitr:如果您想知道,我可以解释发生了什么,但首先,您必须确保您的代码在传递给knitr. 随着错误的消除,您观察到的奇怪现象也将消失。

于 2013-10-12T05:36:40.937 回答