StackOverflow Python 相关问题精选

# 基础语法

# str

如何在 Python 中检查一个字符串否可转化为数字？ (opens new window)

# list

# 🔗 (opens new window)
- Python 中的 appen 和 extend (opens new window)
- append 和 extend 的区别 (opens new window)
# 🔗 (opens new window)
- 获得 Python 的循环索引 (opens new window)
- 在循环中获取索引(数组下标) (opens new window)

# 🔗 (opens new window)

def foo(a=[]):        
    a.append(5)
    return a
# out
>>> foo()
[5]
>>> foo()
[5, 5]
>>> foo()
[5, 5, 5]
>>> foo()
[5, 5, 5, 5]
>>> foo()
# 改写

def foo(a=None):
    if a is None:
        a = list()        
    a.append(5)
    return a

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Python 中的"小震撼":变化的默认参数 (opens new window)

# 🔗 (opens new window)

l = [[1, 2, 3], [4, 5, 6], [7], [8, 9]]
flat_list = [item for sublist in l for item in sublist]
print(flat_list)

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在嵌套列表中获取 flat list|即：列表展开 (opens new window)

# 🔗 (opens new window)
- 怎么样获取一个列表的长度? (opens new window)
# 🔗 (opens new window)
```
tuple(l[i:i+n] for i in xrange(0, len(l), n))
```
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- 在 Python 怎么样才能把列表分割成同样大小的块? (opens new window)
# 🔗 (opens new window)
- 如何克隆或者 copy 一个 list ? (opens new window)
# 🔗 (opens new window)
- 获取列表最后一个元素 (opens new window)
# 🔗 (opens new window)
- 如何删除 list 中指定 index 的元素? (opens new window)
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- 合并两个列表 (opens new window)
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- 使用列表推导式的方式来创建字典 (opens new window)
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- 如何使打印的内容没有空格或换行 (opens new window)
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- 检查列表是否为空的最好方法 (opens new window)
# 🔗 (opens new window)
- 查找列表中某个元素的下标 (opens new window)

# dict

# 时间

# 🔗 (opens new window)
- 在 Python 里获取当前时间 (opens new window)
- 如何在 Python 中获取当前时间 (opens new window)

# 文件

#

# 基本数据结构

# 🔗 (opens new window)

list_to_be_sorted = [{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]   # >>> [{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
newlist = sorted(list_to_be_sorted, key=lambda k: k['name'])
# 或者用标准库中的方法:
from operator import itemgetter
newlist = sorted(list_to_be_sorted, key=itemgetter('name'))