48 lines
1.8 KiB
Markdown
48 lines
1.8 KiB
Markdown
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---
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title: Python Slicestartstopstep
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---
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`slice(start:stop[:step])` is an object usually containing a portion of a sequence. A slice is created using the subscript notation, [] with colons between numbers when several are given, such as in variable_name[1:3:5].
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## Arguments
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This function can be used to slice tuples, arrays and lists.
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The value of the `start` parameter (or None if not provided)
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The value of the `stop` parameter (or last index of sequence)
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The value of the `step` parameter (or None if not provided). It cannot be 0.
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All three must be of integer type.
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## Return
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If only `stop` is provided, it generates portion of sequence from index `0` till `stop`.
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If only `start` is provided, it generates portion of sequence after index `start` till last element.
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If both `start` and `stop` are provided, it generates portion of sequence after index `start` till `stop`.
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If all three `start`, `stop` and `step` are provided, it generates portion of sequence after index `start` till `stop` with increment of index `step`.
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## Example
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a = [1, 2, 3, 4, 5, 6, 7, 8]
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print(a[:5]) # prints [1, 2, 3, 4, 5]
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print(a[2:]) # prints [3, 4, 5, 6, 7, 8]
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print(a[2:5]) # prints [3, 4, 5]
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print(a[2:7:2]) # prints [3, 5, 7]
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You can index the last index of a sequence by using `-1`:
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a = [1, 2, 3, 4, 5, 6]
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print(a[-1]) # prints 6
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print(a[2:-1]) # prints [3, 4, 5]
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You can flip a sequence by using the `[::-1]` slice notation:
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a = [1, 2, 3, 4, 5, 6]
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print(a[::-1]) # prints [6, 5, 4, 3, 2, 1]
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<a href='https://docs.python.org/3/library/functions.html#slice' target='_blank' rel='nofollow'>Official Documentation</a>
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 <a href='https://repl.it/CT5h' target='_blank' rel='nofollow'>Run Code</a>
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