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79 lines
1.2 KiB
Plaintext
79 lines
1.2 KiB
Plaintext
```{r}
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library(randomForest)
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library(MASS)
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library(tree)
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data(Boston)
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```
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## Sampling
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```{r}
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set.seed(123)
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appr = sample(1:nrow(Boston), nrow(Boston) / 2)
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```
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## Regression Tree
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```{r}
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arbre.boston = tree(medv ~ ., Boston, subset = appr)
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summary(arbre.boston)
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plot(arbre.boston)
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text(arbre.boston, pretty = 0)
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```
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```{r}
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cv.boston = cv.tree(arbre.boston)
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plot(cv.boston$size, cv.boston$dev, type = 'b')
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```
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```{r}
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yprev = predict(arbre.boston, newdata = Boston[-appr, ])
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boston.test = Boston[-appr, "medv"]
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plot(yprev, boston.test)
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abline(0, 1)
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mean((yprev - boston.test)^2)
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```
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## Bagging
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```{r}
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set.seed(123)
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bag.boston = randomForest(
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medv ~ .,
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data = Boston,
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subset = appr,
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mtry = 13,
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importance = TRUE
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)
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bag.boston
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yprev.bag = predict(bag.boston, newdata = Boston[-appr, ])
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plot(yprev.bag, boston.test)
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abline(0, 1)
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mean((yprev.bag - boston.test)^2)
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```
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## Random Forest
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```{r}
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set.seed(123)
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rf.boston = randomForest(
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medv ~ .,
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data = Boston,
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subset = appr,
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mtry = 6,
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importance = TRUE
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)
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yprev.rf = predict(rf.boston, newdata = Boston[-appr, ])
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mean((yprev.rf - boston.test)^2)
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```
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## Variable importance
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```{r}
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importance(rf.boston)
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varImpPlot(rf.boston)
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``` |