【发布时间】:2013-07-11 09:37:45
【问题描述】:
由于MASS 包中的stepAIC() 函数在函数中使用时出现问题,我将它与do.call() 一起使用(描述为here)。
我的问题听起来很简单,但我找不到解决方案:当我将do.call() 用于具有多个栅格图层的lm() 模型时,所有图层都保存在模型中。如果我想打印模型的summary(),它会在输出中写入所有层,它会变得非常混乱。如何获得“正常”summary 输出,就像不使用 do.call 一样?
这是一个简短的例子:
创建栅格图层列表:
xz.list <- lapply(1:5,function(x){
r1 <- raster(ncol=3, nrow=3)
values(r1) <- 1:ncell(r1)
r1
})
将它们转换为data.frame:
xz<-getValues(stack(xz.list))
xz <- as.data.frame(xz)
将do.call 用于lm 模型:
fit1<-do.call("lm", list(xz[,1] ~ . , data = xz))
summary() 输出如下所示:
summary(fit1)
Call:
lm(formula = xz[, 1] ~ ., data = structure(list(layer.1 = 1:9,
layer.2 = 1:9, layer.3 = 1:9, layer.4 = 1:9, layer.5 = 1:9), .Names = c("layer.1",
"layer.2", "layer.3", "layer.4", "layer.5"), row.names = c(NA,
-9L), class = "data.frame"))
Residuals:
Min 1Q Median 3Q Max
-9.006e-16 -2.472e-16 -2.031e-16 -1.370e-16 1.724e-15
Coefficients: (4 not defined because of singularities)
Estimate Std. Error t value Pr(>|t|)
(Intercept) 1.184e-15 5.784e-16 2.047e+00 0.0798 .
layer.1 1.000e+00 1.028e-16 9.729e+15 <2e-16 ***
layer.2 NA NA NA NA
layer.3 NA NA NA NA
layer.4 NA NA NA NA
layer.5 NA NA NA NA
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Residual standard error: 7.962e-16 on 7 degrees of freedom
Multiple R-squared: 1, Adjusted R-squared: 1
F-statistic: 9.465e+31 on 1 and 7 DF, p-value: < 2.2e-16
在这个小例子中这看起来还不错,但是当您使用 10 个或更多 raster 层,每个层大约有 32k 个值时,它就会变得一团糟。所以我想让输出看起来像我只使用没有do.call的summary(lm)函数:
fit<-lm(xz[,1] ~ . , data=xz)
summary(fit)
Call:
lm(formula = xz[, 1] ~ ., data = xz)
Residuals:
Min 1Q Median 3Q Max
-9.006e-16 -2.472e-16 -2.031e-16 -1.370e-16 1.724e-15
Coefficients: (4 not defined because of singularities)
Estimate Std. Error t value Pr(>|t|)
(Intercept) 1.184e-15 5.784e-16 2.047e+00 0.0798 .
layer.1 1.000e+00 1.028e-16 9.729e+15 <2e-16 ***
layer.2 NA NA NA NA
layer.3 NA NA NA NA
layer.4 NA NA NA NA
layer.5 NA NA NA NA
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Residual standard error: 7.962e-16 on 7 degrees of freedom
Multiple R-squared: 1, Adjusted R-squared: 1
F-statistic: 9.465e+31 on 1 and 7 DF, p-value: < 2.2e-16
【问题讨论】: