问题描述
我正在处理自定义R程序包(它是私有的，不在任何地方托管).在此程序包中，我有一个函数，该函数接受xgboost，RandomForest(来自Ranger函数)和glmnet模型，并使用它们对新数据集进行预测.
I'm working on a custom R package (it is private, not hosted anywhere). In this package, I have a function that takes xgboost, RandomForest (from the ranger function), and glmnet models and uses them to predict on a new dataset.
每次进行预测时，我都使用相同的广义预测功能.如果我没有为函数命名空间，则R不知道要使用哪个库进行预测.
Each time I'm predicting, I use the same generalized predict function. If I don't namespace the function, R doesn't know which library to use for the predict.
我得到的错误是:
Error in UseMethod("predict") :
no applicable method for 'predict' applied to an object of class "c('lognet', 'glmnet')"
如果我手动加载功能，它可以工作，但是我知道在R库中手动加载软件包是禁忌.
If I load the functions manually, it works, but I know that loading packages manually within an R library is a taboo.
我尝试使用glmnet :: glmnet.predict等，但这也给了我错误.为了避免手动加载库，对这些预测函数进行命名空间的正确方法是什么?
I tried using glmnet::glmnet.predict, etc. but this is giving me errors, as well. What would be the proper way to namespace these predict functions to avoid loading the libraries manually?
推荐答案
例如，在可行的情况下，我自己遇到了这个问题:
I've run into this myself on occasion where, for example, this works:
ranger::predictions(predict(model, data))
但这在相同情况下不会:
but this does not, under identical circumstances:
predict(model, data)
您的程序包大概是Import所必需的依赖项，但是各种S3方法(包括predict.<class>())都不会注册使用，除非您告诉R在程序中的某个早些时候使用它们..您可以通过在给定函数的顶部或.onLoad()中添加requireNamespace(<package name>, quietly = TRUE)来解决此问题.这会导致R注册适当的S3方法等，您可以通过前后检查methods(predict)来确认.重要的是，这对于不允许使用roxygen2声明(例如#' @importFrom <package name> <predict.class>)的 non-exported 方法是正确的.
Your package presumably Imports the necessary dependency, but the various S3 methods, including predict.<class>(), are never registered for use unless you tell R to use them at some point earlier in your program. You can fix this by adding requireNamespace(<package name>, quietly = TRUE) either at the top of the given function or in .onLoad(). This causes R to register the appropriate S3 methods, etc., and you can confirm this by checking methods(predict) before and after. Importantly, this is true for non-exported methods that disallow roxygen2 declarations like #' @importFrom <package name> <predict.class>.
在上面的特定示例中，:: 导致R加载ranger 及其各种S3方法(包括predict.ranger())，因此predict()可以很好地进行分派.
In my particular example above, :: causes R to load ranger along with its various S3 methods, including predict.ranger(), so predict() dispatches just fine.
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