[英]Functionality of probability=TRUE in svm function of e1071 package in R
在R中, e1071
包的svm
函数中probability=TRUE
的功能是什么?
model <- svm (Type ~ ., data, probability=TRUE, cost = 100, gamma = 1)
Setting the probability
argument to TRUE
for both model fitting and prediction returns, for each prediction, the vector of probabilities of belonging to each class of the response variable. 对于每个预测,将模型拟合和预测返回的
probability
参数设置为TRUE
,属于响应变量的每个类的概率向量。 These are stored in a matrix, as an attribute of the prediction object. 它们存储在矩阵中,作为预测对象的属性。
For example: 例如:
library(e1071)
model <- svm(Species ~ ., data = iris, probability=TRUE)
# (below I'm just predicting to the training dataset - it could of course just
# as easily be a separate test dataset)
pred <- predict(model, iris, probability=TRUE)
head(attr(pred, "probabilities"))
# setosa versicolor virginica
# 1 0.9803339 0.01129740 0.008368729
# 2 0.9729193 0.01807053 0.009010195
# 3 0.9790435 0.01192820 0.009028276
# 4 0.9750030 0.01531171 0.009685342
# 5 0.9795183 0.01164689 0.008834838
# 6 0.9740730 0.01679643 0.009130620
Note, however, that it's important to set probability=TRUE
for the call to svm
, and not just the call to predict
, since the latter alone would produce: 但请注意,为
svm
调用设置probability=TRUE
很重要,而不仅仅是调用predict
,因为后者单独会产生:
# setosa versicolor virginica
# 1 0.3333333 0.3333333 0.3333333
# 2 0.3333333 0.3333333 0.3333333
# 3 0.3333333 0.3333333 0.3333333
# 4 0.3333333 0.3333333 0.3333333
# 5 0.3333333 0.3333333 0.3333333
# 6 0.3333333 0.3333333 0.3333333
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