blocks|key|1439837|text|您实际上并没有声明一些东西，但这就是在Python中创建数组的方式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1439838|from+array+import+array
intarray+=+array('i')|code-block|syntax|javascript|1439839|有关更多信息，请参阅数组模块：http://docs.python.org/library/array.html|offset|length|1439840|现在你可能不想要一个数组，而是一个列表，但是其他人已经回答了这个问题。:)|1439841|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/library/array.html^0|0|0|F|15|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@$I|X|J|Y|1|Z]]|A|$]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

You don't actually declare things, but this is how you create an array in Python:

<pre><code>from array import array
intarray = array('i')
</code></pre>

For more info see the array module: <a href="http://docs.python.org/library/array.html" rel="noreferrer">http://docs.python.org/library/array.html</a>

Now possible you don't want an array, but a list, but others have answered that already. :)

blocks|key|1225192|text|我想你(意思是)想要一个已经填满了前30个单元格的列表。所以|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1225193|+++f+=+[]

+++for+i+in+range(30):
+++++++f.append(0)|code-block|syntax|javascript|1225194|可以使用这种方法的一个例子是斐波那契数列。查看Project+Euler中的问题2|offset|length|1225195|entityMap|0|LINK|mutability|MUTABLE|url|http://projecteuler.net/^0|0|0|N|D|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

I think you (meant)want an list with the first 30 cells already filled.
So

<pre><code> f = []

 for i in range(30):
 f.append(0)
</code></pre>

An example to where this could be used is in Fibonacci sequence.
See problem 2 in <a href="http://projecteuler.net/" rel="noreferrer">Project Euler</a>

blocks|key|1439725|text|这是如何实现的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1439726|my_array+=+[1,+'rebecca',+'allard',+15]|code-block|syntax|javascript|1439727|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This is how:

<pre><code>my_array = [1, 'rebecca', 'allard', 15]
</code></pre>

blocks|key|1439988|text|对于计算，使用numpy数组，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1439989|import+numpy+as+np

a+=+np.ones((3,2))++++++++#+a+2D+array+with+3+rows,+2+columns,+filled+with+ones
b+=+np.array([1,2,3])+++++#+a+1D+array+initialised+using+a+list+[1,2,3]
c+=+np.linspace(2,3,100)++#+an+array+with+100+points+beteen+(and+including)+2+and+3

print(a*1.5)++#+all+elements+of+a+times+1.5
print(a.T%2Bb)++#+b+added+to+the+transpose+of+a|code-block|syntax|javascript|1439990|这些numpy数组可以保存并从磁盘加载(即使是压缩的)，具有大量元素的复杂计算速度类似于C。|1439991|在科学环境中经常使用。有关详细信息，请参阅here。|1439992|entityMap|0|LINK|mutability|MUTABLE|url|http://numpy.scipy.org/|1|http://docs.scipy.org/doc/numpy-1.6.0/user/whatisnumpy.html^0|7|5|0|0|0|0|L|4|1|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|11|8|@]|9|@]|C|$]]|$1|K|3|L|5|6|7|12|8|@]|9|@$A|13|B|14|1|15]]|C|$]]|$1|M|3|-4|5|6|7|16|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]|U|$5|P|Q|R|C|$S|V]]]]

For calculations, use <a href="http://numpy.scipy.org/" rel="noreferrer">numpy</a> arrays like this:

<pre><code>import numpy as np

a = np.ones((3,2)) # a 2D array with 3 rows, 2 columns, filled with ones
b = np.array([1,2,3]) # a 1D array initialised using a list [1,2,3]
c = np.linspace(2,3,100) # an array with 100 points beteen (and including) 2 and 3

print(a*1.5) # all elements of a times 1.5
print(a.T+b) # b added to the transpose of a
</code></pre>

these numpy arrays can be saved and loaded from disk (even compressed) and complex calculations with large amounts of elements are C-like fast. 

Much used in scientific environments. See <a href="http://docs.scipy.org/doc/numpy-1.6.0/user/whatisnumpy.html" rel="noreferrer">here</a> for more.

blocks|key|1225418|text|一些贡献表明，python中的数组由列表表示。这是不正确的。Python在标准库模块array+"array.array()“中有一个独立的array()实现，因此将两者混淆是不正确的。列表是python中的列表，所以要小心使用命名法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1225419|list_01+=+[4,+6.2,+7-2j,+'flo',+'cro']

list_01
Out[85]:+[4,+6.2,+(7-2j),+'flo',+'cro']|code-block|syntax|javascript|1225420|list和array.array()之间有一个非常重要的区别。虽然这两个对象都是有序序列，但array.array()是有序的同类序列，而列表是非同类序列。|1225421|entityMap^0|16|5|1D|D|1Y|7|0|0|5|D|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|N|$]]

A couple of contributions suggested that arrays in python are represented by lists. This is incorrect. Python has an independent implementation of <code>array()</code> in the standard library module <code>array</code> "<code>array.array()</code>" hence it is incorrect to confuse the two. Lists are lists in python so be careful with the nomenclature used. 

<pre><code>list_01 = [4, 6.2, 7-2j, 'flo', 'cro']

list_01
Out[85]: [4, 6.2, (7-2j), 'flo', 'cro']
</code></pre>

There is one very important difference between list and <code>array.array()</code>. While both of these objects are ordered sequences, array.array() is an ordered homogeneous sequences whereas a list is a non-homogeneous sequence.

blocks|key|1440205|text|JohnMachin's+comment应该是真正的答案。在我看来，所有其他的答案都只是权宜之计！所以：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1440206|array=[0]*element_count|code-block|syntax|javascript|1440207|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/1514553/how-to-declare-an-array-in-python#comment4894793_4476624^0|0|K|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

<a href="https://stackoverflow.com/questions/1514553/how-to-declare-an-array-in-python#comment4894793_4476624">JohnMachin's comment</a> should be the real answer.
All the other answers are just workarounds in my opinion!
So:

<pre><code>array=[0]*element_count
</code></pre>

blocks|key|1439769|text|在Python中不需要声明任何东西。你只需要使用它。我建议你从像http://diveintopython.net这样的东西开始。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1439770|entityMap|0|LINK|mutability|MUTABLE|url|http://diveintopython.net/^0|W|P|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

You don't declare anything in Python. You just use it. I recommend you start out with something like <a href="http://diveintopython.net" rel="noreferrer">http://diveintopython.net</a>.

blocks|key|1439803|text|我通常只使用a+=+[1,2,3]，它实际上是一个list，但是对于arrays，请看这个正式的definition|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1439804|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/library/array.html^0|6|B|P|4|Y|6|1C|A|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]|$9|S|A|T|B|C]]|D|@$9|U|A|V|1|W]]|E|$]]|$1|F|3|-4|5|6|7|X|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

I would normally just do <code>a = [1,2,3]</code> which is actually a <code>list</code> but for <code>arrays</code> look at this formal <a href="http://docs.python.org/library/array.html" rel="noreferrer">definition</a>

blocks|key|1225263|text|这个怎么样..。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1225264|>>>+a+=+range(12)
>>>+a
[0,+1,+2,+3,+4,+5,+6,+7,+8,+9,+10,+11]
>>>+a[7]
6|code-block|syntax|javascript|1225265|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

How about this...

<pre><code>&gt;&gt;&gt; a = range(12)
&gt;&gt;&gt; a
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
&gt;&gt;&gt; a[7]
6
</code></pre>

blocks|key|1439866|text|继Lennart之后，还有实现同构多维数组的numpy。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1439867|entityMap|0|LINK|mutability|MUTABLE|url|http://numpy.scipy.org/^0|M|5|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Following on from Lennart, there's also <a href="http://numpy.scipy.org/" rel="noreferrer">numpy</a> which implements homogeneous multi-dimensional arrays.

blocks|key|1440041|text|Python称它们为lists。您可以使用方括号和逗号编写列表文字：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1440042|>>>+[6,28,496,8128]
[6,+28,+496,+8128]|code-block|syntax|javascript|1440043|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/2/tutorial/introduction.html#lists^0|A|5|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Python calls them <a href="http://docs.python.org/2/tutorial/introduction.html#lists" rel="noreferrer">lists</a>. You can write a list literal with square brackets and commas:

<pre><code>&gt;&gt;&gt; [6,28,496,8128]
[6, 28, 496, 8128]
</code></pre>

blocks|key|1440092|text|我有一个字符串数组，并且需要一个初始化为True的相同长度的布尔值数组。我就是这么做的|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1440093|strs+=+["Hi","Bye"]+
bools+=+[+True+for+s+in+strs+]|code-block|syntax|javascript|1440094|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I had an array of strings and needed an array of the same length of booleans initiated to True. This is what I did

<pre><code>strs = ["Hi","Bye"] 
bools = [ True for s in strs ]
</code></pre>

blocks|key|1225483|text|您可以创建列表并将其转换为数组，也可以使用numpy模块创建数组。下面是几个例子来说明这一点。Numpy还使得处理多维数组变得更容易。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1225484|import+numpy+as+np
a+=+np.array([1,+2,+3,+4])

#For+custom+inputs
a+=+np.array([int(x)+for+x+in+input().split()])|code-block|syntax|javascript|1225485|您还可以使用重塑函数将此数组重塑为2X2矩阵，该函数接受输入作为矩阵的维度。|1225486|mat+=+a.reshape(2,+2)|1225487|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You can create lists and convert them into arrays or you can create array using numpy module. Below are few examples to illustrate the same. Numpy also makes it easier to work with multi-dimensional arrays.

<pre><code>import numpy as np
a = np.array([1, 2, 3, 4])

#For custom inputs
a = np.array([int(x) for x in input().split()])
</code></pre>

You can also reshape this array into a 2X2 matrix using reshape function which takes in input as the dimensions of the matrix.

<pre><code>mat = a.reshape(2, 2)
</code></pre>

blocks|key|1440272|text|#+This+creates+a+list+of+5000+zeros
a+=+[0]+*+5000++|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1440273|您可以使用与数组相同的表示法来读写此列表中的任何元素。|unstyled|1440274|它似乎确实具有与数组相同的随机访问性能。我不能说它是如何分配内存的，因为如果您需要的话，它还支持不同类型的混合，包括字符串和对象。|1440275|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code># This creates a list of 5000 zeros
a = [0] * 5000 
</code></pre>
You can read and write to any element in this list with a[n] notation in the same as you would with an array.
It does seem to have the same random access performance as an array. I cannot say how it allocates memory because it also supports a mix of different types including strings and objects if you need it to.

How do I declare an array in <a href="http://en.wikipedia.org/wiki/Python_%28programming_language%29" rel="noreferrer">Python</a>?

I can't find any reference to arrays in the documentation.

How to declare an array in Python?

Python

如何在中声明数组我在文档中找不到任何对数组的引用。

问如何在Python中声明数组？
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