Contare e individuare i valori

Before any analysis, you want a feel for what is inside a Series. A few quick methods summarize the contents in seconds. 🔍

Here is a Series of fruit names with some repeats. We will explore its contents with handy built-in methods.

The value_counts method tallies how often each value appears, sorted from most to least common. It is the fastest frequency check.

Call unique to get every distinct value just once, in the order first seen. It answers what kinds of values you have.

The nunique method returns the count of distinct values as a single number. Here it tells you how many fruit kinds exist.

Add normalize=True to value_counts and you get proportions instead of raw counts. Now each fruit's share sums to one.

The isna method flags each value that is missing as True. Summing those flags counts the gaps in your column at a glance.

Use isin with a list to test which values belong to a chosen set. It returns a boolean mask you can filter with later.

For numbers, max and min surface the largest and smallest values instantly, without sorting the whole Series yourself.

The describe method bundles count, unique, top, and frequency for text, giving a tidy snapshot in a single call. 📋

Together these methods are your first inspection pass on any column. A minute spent here saves hours of confused analysis later. 🧰

Pick the right tool for a frequency tally.

You can now profile a Series with value_counts, unique, nunique, isna, and isin. These quick checks reveal what your data holds. Well done! 🎉