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Added dict items() snippet. Tweaked a few snippets and comments.

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This commit is contained in:
Donne Martin 2015-01-26 12:58:58 -05:00
parent 5131bc8a46
commit c8a06dcd85
1 changed files with 35 additions and 34 deletions
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69
core/structs.ipynb
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@ -1,7 +1,7 @@
{ {
"metadata": { "metadata": {
"name": "", "name": "",
"signature": "sha256:6d8f33055bf348eb4c2871340e68a3f7577e0a027f5c83423e35757e01e8243a" "signature": "sha256:af3d280883daa542ff4a3cccb240979e6b7c05fbe40cac48675cc8ef613e3483"
}, },
"nbformat": 3, "nbformat": 3,
"nbformat_minor": 0, "nbformat_minor": 0,
@ -902,7 +902,7 @@
"cell_type": "markdown", "cell_type": "markdown",
"metadata": {}, "metadata": {},
"source": [ "source": [
"dict keys must be \"hashable\": immutable objects like scalars (int, float, string) or tuples whose objects are all immutable." "dict keys must be \"hashable\": immutable objects like scalars (int, float, string) or tuples whose objects are all immutable. Lists are mutable and therefore are not hashable, although you can convert the list portion to a tuple as a quick fix"
] ]
}, },
{ {
@ -926,35 +926,6 @@
], ],
"prompt_number": 32 "prompt_number": 32
}, },
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Lists are mutable and therefore are not hashable, although you can convert the list portion to a tuple as a quick fix"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"hash((1, 2, [3, 4]))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"ename": "TypeError",
"evalue": "unhashable type: 'list'",
"output_type": "pyerr",
"traceback": [
"\u001b[0;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[0;31mTypeError\u001b[0m Traceback (most recent call last)",
"\u001b[0;32m<ipython-input-33-94f25bbf31b2>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mhash\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m2\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m[\u001b[0m\u001b[0;36m3\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m4\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
"\u001b[0;31mTypeError\u001b[0m: unhashable type: 'list'"
]
}
],
"prompt_number": 33
},
{ {
"cell_type": "markdown", "cell_type": "markdown",
"metadata": {}, "metadata": {},
@ -974,13 +945,13 @@
{ {
"metadata": {}, "metadata": {},
"output_type": "pyout", "output_type": "pyout",
"prompt_number": 34, "prompt_number": 33,
"text": [ "text": [
"['a', 'b', 5, 'z']" "['a', 'b', 5, 'z']"
] ]
} }
], ],
"prompt_number": 34 "prompt_number": 33
}, },
{ {
"cell_type": "markdown", "cell_type": "markdown",
@ -1001,12 +972,42 @@
{ {
"metadata": {}, "metadata": {},
"output_type": "pyout", "output_type": "pyout",
"prompt_number": 35, "prompt_number": 34,
"text": [ "text": [
"['foo', [0, 1, 2, 3], 'bar', None]" "['foo', [0, 1, 2, 3], 'bar', None]"
] ]
} }
], ],
"prompt_number": 34
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Iterate through a dictionary's keys and values"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"for key, value in dict_1.items():\n",
" print key, value"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"a foo\n",
"b [0, 1, 2, 3]\n",
"5 bar\n",
"z None\n"
]
}
],
"prompt_number": 35 "prompt_number": 35
}, },
{ {