Apa iku generator lan keyword yield?

Question

Accepted Answer

A **generator** yaiku fungsi sing ngasilake nilai **kanthi malas, siji-siji**, nggunakake keyword `yield` tinimbang `return`. Genarator nglakokno saben nilai nalika dijaluk tinimbang mbangun seluruh asil ing memori — ideal kanggo urutan gedhe utawa tanpa wates.

## yield vs return

```python
# a regular function builds the WHOLE list in memory
def get_squares(n):
    return [i ** 2 for i in range(n)]   # all n values created at once

# a generator yields values ONE AT A TIME, on demand
def gen_squares(n):
    for i in range(n):
        yield i ** 2                     # pause here, return one value, resume on next()

for sq in gen_squares(1_000_000):        # uses almost NO memory
    print(sq)
```

`yield` **mendheg** fungsi, ngasilake nilai, lan **nerusake** saka titik tepat iku ing iterasi sawise — njaga status lokal antarane nilai. Ora ana sing dihitung nganti ditjaluk.

## Manfaat memori

```python
sum(i ** 2 for i in range(10_000_000))   # generator expression — constant memory
sum([i ** 2 for i in range(10_000_000)]) # list — builds a huge list first (wasteful)
```

Wang data gedhe, generator tetep memori datar; list comprehension materialize kabeh ing sarangga.

## Urutan tanpa wates (ora bisa karo list)

```python
def count_up():
    n = 0
    while True:        # infinite — but lazy, so it's fine
        yield n
        n += 1

gen = count_up()
next(gen)   # 0
next(gen)   # 1  — only computes when asked
```

Amarga nilai dihasilake nalika dijaluk, generator bisa makili *tanpa wates* aliran — sampeyan mung njupuk sing sampeyan butuh.

## Cara iterasi gumana ing ing ngisor hood

```python
gen = gen_squares(3)
next(gen)   # 0  — runs until the first yield
next(gen)   # 1  — resumes, runs to the next yield
next(gen)   # 4
next(gen)   # StopIteration — generator exhausted
```

## Ekspresi generator

```python
(x ** 2 for x in range(10))   # like a list comprehension but lazy (parentheses)
```

## Kenapa iku penting

Generator penting kanggo **proses sing efisien memori** data gedhe utawa streaming — maca berkas ageng baris demi baris, proses dataset gedhe, pipeline, utawa urutan tanpa wates — kang mbangun list lengkap bakal ngobongi memori.

Nanggerti `yield` (stop/nerusake karo negara njaga) lan lazy evaluation ngidini sampeyan nulis kode proses data sing bisa dikembangake, lan ekspresi generator nyedhiyake manfaat padha kanthi ringkes.

Kabeh perangkat kunci nalika data gedhe banget kanggo lenggah ing memori utawa sampeyan kepingin proses item amarga dihasilake tinimbang kabeh ing ngarep.