เปลี่ยนเป็นตัวพิมพ์เล็กและตัดช่องว่าง

The simplest normalization is folding case and trimming spaces. Master these two and you already remove most of the noise that splits your word counts. ✨

Python strings carry a built-in lower method. It returns a fresh copy with every letter folded to lowercase, leaving the original untouched.

Once both sides are lowercased, the case difference vanishes and the comparison finally returns True. That is the whole point of case folding.

The strip method removes whitespace from both ends of a string. Leading and trailing spaces, tabs, and newlines all disappear in one call.

Sometimes you only want one edge cleaned. Use lstrip for the left side and rstrip for the right when you need that control.

Strip only touches the ends. To squash repeated spaces inside text, split on whitespace and rejoin, which collapses every gap to a single space.

Calling split with no argument breaks on any run of whitespace and drops the empties. Rejoining with one space gives you clean, even spacing.

Because each method returns a string, you can chain them. Here you lowercase and strip a value in a single readable pipeline.

These methods never change the original; they hand back a new string. Always capture the result in a variable or you lose the cleaned value.

Apply your two steps to every token at once with a comprehension. Now each word is lowercase and trimmed, ready for counting.

After folding case, the three messy entries for cat collapse into one matching token, so your frequency table tells the truth. 📊

Let's confirm how to clean spacing.

You learned to fold case with lower and trim edges with strip, then collapse inner gaps with split and join. Your tokens now match cleanly. Nice work! 🎉