Slicing inaondoa sehemu ya mlolongo (orodha, tuple, kamba) kwa kutumia sintaksia sequence[start:stop:step]. Ni sifa yenye nguvu na fupi inayotumiwa kila wakati katika Python.
nums = [, , , , , ]
nums[:]
nums[:]
nums[:]
nums[:]
Kanuni kuu: start ni kamata, stop ni haswa (nums[1:4] inatoa fahirisi 1, 2, 3 — si 4).
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
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] inayobadilisha mlolongo ni mojawapo ya idiom za Python zinazojulikana zaidi.
s = "Hello"
s[1:4] # "ell"
s[::-1] # "olleH" — reverse a string
s[0] # "H"
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]
nums[10:20] # [] — out-of-range slices return empty, don't crash (unlike nums[10])
Bila ya kufikia faharasa moja (ambayo huinuka IndexError), slicing kwa fadhaili inarudi kile kinachokuwepo.
Slicing ni sifa ya kila mahali, inayotsukuza Python kwa ajili ya kuondoa, kunakili, na kubadilisha mlolongo kwa nasi.
Kuelewa sintaksia start:stop:step (hasa kukamatia-mula/kupuuza-hadi), fahirisi hasi (kuhesabu kutoka mwisho), idiom ya reverse ([::-1]), na kwamba slices ni salama (hakuna kubomoka kwa nje ya eneo) hukuruhusu kuandaa orodha na kamba kwa njia fupi na sahihi.
Inabadilisha loops zenye kina kwa operesheni za kawaida na inaonekana katika kod yote ya idiomatiki ya Python.