Pados cara slicing gawe ing Python?

Question

Accepted Answer

**Slicing** ngrucut sebagian seko sequence (list, tuple, string) nganggo syntax `sequence[start:stop:step]`. Iki minangka feature sing kuwat lan ringkes, digunakake terus-terusan ing Python.

## Slicing dasar

```python
nums = [0, 1, 2, 3, 4, 5]

nums[1:4]     # [1, 2, 3]   — start at index 1, up to (NOT including) 4
nums[:3]      # [0, 1, 2]   — from the start (start defaults to 0)
nums[3:]      # [3, 4, 5]   — to the end (stop defaults to len)
nums[:]       # [0, 1, 2, 3, 4, 5] — a full (shallow) COPY
```

Aturan utama: `start` **kalebu**, `stop` **ora kalebu** (`nums[1:4]` menehi indeks 1, 2, 3 — dudu 4).

## Indeks negatif ditung seko mburi

```python
nums[-1]      # 5  — last element
nums[-2]      # 4  — second to last
nums[-3:]     # [3, 4, 5] — last three elements
nums[:-1]     # [0, 1, 2, 3, 4] — everything except the last
```

## Parameter step

```python
nums[::2]     # [0, 2, 4]      — every 2nd element
nums[1::2]    # [1, 3, 5]      — every 2nd, starting at index 1
nums[::-1]    # [5, 4, 3, 2, 1, 0] — REVERSE the sequence (a famous idiom)
```

`nums[::-1]` mbalikno sequence minangka salah sawijining idiom Python sing paling dikenal.

## Slicing string

```python
s = "Hello"
s[1:4]        # "ell"
s[::-1]       # "olleH" — reverse a string
s[0]          # "H"
```

## Slice assignment (kanggo list sing bisa diganti)

```python
nums = [0, 1, 2, 3, 4]
nums[1:3] = [10, 20, 30]   # replace a slice (can change length)
# nums → [0, 10, 20, 30, 3, 4]
```

## Slicing aman (ora ana IndexError)

```python
nums[10:20]   # [] — out-of-range slices return empty, don't crash (unlike nums[10])
```

Kabéh saka single-index access (sing ndang `IndexError`), slicing kanthi becik balik apa sing ana.

## Kenapa iku penting

Slicing minangka feature sing ngliyeng-liyeng, khas-Python kanggo ngrucut, nggandeng, lan mbalikno sequence kanthi resik.

Mangerteni syntax `start:stop:step` (utamane inclusive-start/exclusive-stop), indeks negatif (ditung seko mburi), idiom mbalik (`[::-1]`), lan slicing aman (ora rusak ing jangkauan ora bener) ngidini sampeyan manipulasi list lan string kanthi ringkes lan bener.

Iki ngganti loop sing cethak kanggo operasi umum lan katon ing seluruh kode Python sing idiomatis.