Exploratory data analysis

The first step of any data analysis, unsupervised or supervised, is to familiarize yourself with the data.

The variables you created before, wisc.data and diagnosis, are still available in your workspace. Explore the data to answer the following questions:

1. How many observations are in this dataset?
2. How many variables/features in the data are suffixed with _mean?
3. How many of the observations have a malignant diagnosis?