Performing PCA
The next step in your analysis is to perform PCA on wisc.data.
You saw in the last chapter that it's important to check if the data need to be scaled before performing PCA. Recall two common reasons for scaling data:
- The input variables use different units of measurement.
- The input variables have significantly different variances.
Questo esercizio fa parte del corso
Unsupervised Learning in R
Istruzioni dell'esercizio
The variables you created before, wisc.data and diagnosis, are still available in your workspace.
- Check the mean and standard deviation of the features of the data to determine if the data should be scaled. Use the
colMeans()andapply()functions like you've done before. - Execute PCA on the
wisc.data, scaling if appropriate, and assign the model towisc.pr. - Inspect a summary of the results with the
summary()function.
Esercizio pratico interattivo
Prova a risolvere questo esercizio completando il codice di esempio.
# Check column means and standard deviations
# Execute PCA, scaling if appropriate: wisc.pr
# Look at summary of results