深度复制 Booster 对象

创建一个 'xgb.Booster' 对象的深度副本，使其包含的 C 对象指针指向一个不同的对象，因此诸如 xgb.attr() 之类的函数不会影响被复制的原始对象。

用法

xgb.copy.Booster(model)

参数

model

一个 'xgb.Booster' 对象。

返回值

model 的深度副本 - 它在各方面都完全相同，但对该副本调用的 C 级别函数不会影响原始 model 变量。

示例

library(xgboost)

data(mtcars)

y <- mtcars$mpg
x <- mtcars[, -1]

dm <- xgb.DMatrix(x, label = y, nthread = 1)

model <- xgb.train(
  data = dm,
  params = xgb.params(nthread = 1),
  nrounds = 3
)

# Set an arbitrary attribute kept at the C level
xgb.attr(model, "my_attr") <- 100
print(xgb.attr(model, "my_attr"))

# Just assigning to a new variable will not create
# a deep copy - C object pointer is shared, and in-place
# modifications will affect both objects
model_shallow_copy <- model
xgb.attr(model_shallow_copy, "my_attr") <- 333
# 'model' was also affected by this change:
print(xgb.attr(model, "my_attr"))

model_deep_copy <- xgb.copy.Booster(model)
xgb.attr(model_deep_copy, "my_attr") <- 444
# 'model' was NOT affected by this change
# (keeps previous value that was assigned before)
print(xgb.attr(model, "my_attr"))

# Verify that the new object was actually modified
print(xgb.attr(model_deep_copy, "my_attr"))