blocks|key|1424700|text|[float(i)+for+i+in+lst]|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1424701|准确地说，它创建了一个带有浮点值的新列表。与map方法不同，它将在py3k中工作。|unstyled|offset|length|style|CODE|1424702|entityMap^0|0|M|3|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@$G|O|H|P|I|J]]|9|@]|A|$]]|$1|K|3|-4|5|F|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>[float(i) for i in lst]
</code></pre>

to be precise, it creates a new list with float values. Unlike the <code>map</code> approach it will work in py3k.

blocks|key|1209883|text|map(float,+mylist)应该做到这一点。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1209884|(在Python3中，map不再返回list对象，所以如果您想要一个新的list，而不仅仅是要迭代的内容，那么您要么需要list(map(float,+mylist)+--要么使用SilentGhost的答案，后者可以说更具有Python风格。)|1209885|entityMap^0|0|I|0|1O|N|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|P|8|@]|D|@]|E|$]]]|I|$]]

<code>map(float, mylist)</code> should do it. 

(In Python 3, map ceases to return a list object, so if you want a new list and not just something to iterate over, you either need <code>list(map(float, mylist)</code> - or use SilentGhost's answer which arguably is more pythonic.)

blocks|key|1209945|text|float(item)做了正确的事情:它将其参数转换为浮点型，并返回它，但它不会原地更改参数。代码的一个简单修复方法是：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1209946|new_list+=+[]
for+item+in+list:
++++new_list.append(float(item))|code-block|syntax|javascript|1209947|使用列表理解可以将相同的代码写得更短：new_list+=+[float(i)+for+i+in+list]|1209948|要就地更改列表，请执行以下操作：|1209949|for+index,+item+in+enumerate(list):
++++list[index]+=+float(item)|1209950|顺便说一句，避免对变量使用list，因为它伪装了同名的内置函数。|1209951|entityMap^0|0|B|0|0|J|Z|0|0|0|D|4|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|11|8|@]|D|@]|E|$]]|$1|O|3|P|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|Q|3|R|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@]|E|$]]|$1|S|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|T|$]]

<code>float(item)</code> do the right thing: it converts its argument to float and and return it, but it doesn't change argument in-place. A simple fix for your code is:

<pre><code>new_list = []
for item in list:
 new_list.append(float(item))
</code></pre>

The same code can written shorter using list comprehension: <code>new_list = [float(i) for i in list]</code>

To change list in-place:

<pre><code>for index, item in enumerate(list):
 list[index] = float(item)
</code></pre>

BTW, avoid using <code>list</code> for your variables, since it masquerades built-in function with the same name.

blocks|key|1209981|text|您可以使用numpy将列表直接转换为浮点数组或矩阵。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1209982|++++import+numpy+as+np
++++list_ex+=+[1,+0]+#+This+a+list
++++list_int+=+np.array(list_ex)+#+This+is+a+numpy+integer+array|code-block|syntax|javascript|1209983|如果要将整数数组转换为浮点数组，则添加0。对它来说|1209984|++++list_float+=+np.array(list_ex)+%2B+0.+#+This+is+a+numpy+floating+array|1209985|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 use numpy to convert a list directly to a floating array or matrix.

<pre><code> import numpy as np
 list_ex = [1, 0] # This a list
 list_int = np.array(list_ex) # This is a numpy integer array
</code></pre>

If you want to convert the integer array to a floating array then add 0. to it

<pre><code> list_float = np.array(list_ex) + 0. # This is a numpy floating array
</code></pre>

blocks|key|1424899|text|这就是我要做的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1424900|my_list+=+['0.49',+'0.54',+'0.54',+'0.54',+'0.54',+'0.54',+'0.55',+'0.54',+
++++'0.54',+'0.54',+'0.55',+'0.55',+'0.55',+'0.54',+'0.55',+'0.55',+'0.54',+
++++'0.55',+'0.55',+'0.54']
print+type(my_list[0])+#+prints+<type+'str'>
my_list+=+[float(i)+for+i+in+my_list]
print+type(my_list[0])+#+prints+<type+'float'>|code-block|syntax|javascript|1424901|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 I would do it.

<pre><code>my_list = ['0.49', '0.54', '0.54', '0.54', '0.54', '0.54', '0.55', '0.54', 
 '0.54', '0.54', '0.55', '0.55', '0.55', '0.54', '0.55', '0.55', '0.54', 
 '0.55', '0.55', '0.54']
print type(my_list[0]) # prints &lt;type 'str'&gt;
my_list = [float(i) for i in my_list]
print type(my_list[0]) # prints &lt;type 'float'&gt;
</code></pre>

blocks|key|1210042|text|import+numpy+as+np
my_list+=+['0.49',+'0.54',+'0.54',+'0.54',+'0.54',+'0.54',+'0.55',+'0.54',+'0.54',+'0.54',+'0.55',+'0.55',+'0.55',+'0.54',+'0.55',+'0.55',+'0.54',+
'0.55',+'0.55',+'0.54']
print(type(my_list),+type(my_list[0]))+++
#+<class+'list'>+<class+'str'>|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1210043|它将类型显示为字符串列表。您可以使用numpy同时将此列表转换为浮点数组：|unstyled|1210044|++++my_list+=+np.array(my_list).astype(np.float)

++++print(type(my_list),+type(my_list[0]))++
++++#+<class+'numpy.ndarray'>+<class+'numpy.float64'>|1210045|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>import numpy as np
my_list = ['0.49', '0.54', '0.54', '0.54', '0.54', '0.54', '0.55', '0.54', '0.54', '0.54', '0.55', '0.55', '0.55', '0.54', '0.55', '0.55', '0.54', 
'0.55', '0.55', '0.54']
print(type(my_list), type(my_list[0])) 
# &lt;class 'list'&gt; &lt;class 'str'&gt;
</code></pre>

which displays the type as a list of strings. You can convert this list to an array of floats simultaneously using numpy:

<pre><code> my_list = np.array(my_list).astype(np.float)

 print(type(my_list), type(my_list[0])) 
 # &lt;class 'numpy.ndarray'&gt; &lt;class 'numpy.float64'&gt;
</code></pre>

blocks|key|1210090|text|这可能是另一种方法(不使用任何循环！)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1210091|import+numpy+as+np
list(np.float_(list_name))|code-block|syntax|javascript|1210092|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 would be an other method (without using any loop!):
<pre><code>import numpy as np
list(np.float_(list_name))
</code></pre>

blocks|key|1425055|text|我已经在我的程序中解决了这个问题，使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1425056|number_input+=+float("{:.1f}".format(float(input())))
list.append(number_input)|code-block|syntax|javascript|1425057|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 have solve this problem in my program using:

<pre><code>number_input = float("{:.1f}".format(float(input())))
list.append(number_input)
</code></pre>

blocks|key|1210178|text|你甚至可以通过numpy做到这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1210179|import+numpy+as+np
np.array(your_list,dtype=float)|code-block|syntax|javascript|1210180|此函数将列表的np数组返回为浮点数|1210181|您还可以将'dtype‘设置为int|1210182|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]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

you can even do this by numpy

<pre><code>import numpy as np
np.array(your_list,dtype=float)
</code></pre>

this return np array of your list as float

you also can set 'dtype' as int

blocks|key|1210245|text|我必须首先从浮点字符串列表中提取数字：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1210246|+++df4['sscore']+=+df4['simscore'].str.findall('\d%2B\.\d%2B')|code-block|syntax|javascript|1210247|然后每一个都转换成一个浮点数：|1210248|+++ad=[]
+++for+z+in+range(len(df4)):
++++++ad.append([float(i)+for+i+in+df4['sscore'][z]])|1210249|最后，将所有浮点数作为float64分配给一个数据帧：|1210250|+++df4['fscore']+=+np.array(ad,dtype=float)|1210251|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I had to extract numbers first from a list of float strings:

<pre><code> df4['sscore'] = df4['simscore'].str.findall('\d+\.\d+')
</code></pre>

then each convert to a float:

<pre><code> ad=[]
 for z in range(len(df4)):
 ad.append([float(i) for i in df4['sscore'][z]])
</code></pre>

in the end assign all floats to a dataframe as float64:

<pre><code> df4['fscore'] = np.array(ad,dtype=float)
</code></pre>

blocks|key|1210260|text|for+i+in+range(len(list)):+list[i]=float(list[i])|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1210261|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>for i in range(len(list)): list[i]=float(list[i])
</code></pre>

blocks|key|1210332|text|您可以使用numpy来避免循环：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1210333|import+numpy+as+np
list(np.array(my_list).astype(float)|code-block|syntax|javascript|1210334|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|$]]

you can use numpy to avoid looping:
<pre><code>import numpy as np
list(np.array(my_list).astype(float)
</code></pre>

blocks|key|1425297|text|您可以使用map()函数将列表直接转换为floats|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1425298|float_list+=+map(float,+list)|code-block|syntax|javascript|1425299|entityMap^0|5|5|K|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

You can use the <code>map()</code> function to convert the list directly to <code>floats</code>:
<pre><code>float_list = map(float, list)
</code></pre>

I have a script which reads a text file, pulls decimal numbers out of it as strings and places them into a list.
So I have this list:
<pre><code>my_list = ['0.49', '0.54', '0.54', '0.55', '0.55', '0.54', '0.55', '0.55', '0.54']
</code></pre>
How do I convert each of the values in the list from a string to a float?
I have tried:
<pre><code>for item in my_list:
 float(item)
</code></pre>
But this doesn't seem to work for me.

In Python, how do I convert all of the items in a list to floats?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个脚本，它读取一个文本文件，从中提取十进制数作为字符串，并将它们放入一个列表中。所以我有这个列表：my_list = ['0.49', '0.54', '0.54', '0.55', '0.55', '0.54', '0.55', '0.55', '0.54']如何将列表中的每个值从字符串转换为浮点型？我试过了：...

问在Python中，如何将列表中的所有项转换为浮点数？
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问在Python中，如何将列表中的所有项转换为浮点数？
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