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    <p>It's pretty simple really:</p> <pre><code>a[start:end] # items start through end-1 a[start:] # items start through the rest of the array a[:end] # items from the beginning through end-1 a[:] # a copy of the whole array </code></pre> <p>There is also the <code>step</code> value, which can be used with any of the above:</p> <pre><code>a[start:end:step] # start through not past end, by step </code></pre> <p>The key point to remember is that the <code>:end</code> value represents the first value that is <em>not</em> in the selected slice. So, the difference beween <code>end</code> and <code>start</code> is the number of elements selected (if <code>step</code> is 1, the default).</p> <p>The other feature is that <code>start</code> or <code>end</code> may be a <em>negative</em> number, which means it counts from the end of the array instead of the beginning. So:</p> <pre><code>a[-1] # last item in the array a[-2:] # last two items in the array a[:-2] # everything except the last two items </code></pre> <p>Similarly, <code>step</code> may be a negative number:</p> <pre><code>a[::-1] # all items in the array, reversed a[1::-1] # the first two items, reversed a[:-3:-1] # the last two items, reversed a[-3::-1] # everything except the last two items, reversed </code></pre> <p>Python is kind to the programmer if there are fewer items than you ask for. For example, if you ask for <code>a[:-2]</code> and <code>a</code> only contains one element, you get an empty list instead of an error. Sometimes you would prefer the error, so you have to be aware that this may happen.</p>
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    1. POUnderstanding Python's slice notation
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    1. USGreg Hewgill
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    1. COSlicing builtin types returns a copy but that's not universal. Notably, [slicing NumPy arrays](http://docs.scipy.org/doc/numpy/reference/arrays.indexing.html) returns a view that shares memory with the original.
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      1. USBeni Cherniavsky-Paskin
 

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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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