merge(*iterables, key=None, reverse=False)写一段python代码
时间: 2024-03-14 11:45:15 浏览: 27
下面是一个简单的示例代码,演示如何使用merge()函数将多个有序列表合并成一个有序列表:
```python
from heapq import merge
# 定义多个有序列表
list1 = [1, 4, 6, 8]
list2 = [2, 3, 5, 7, 9]
list3 = [0, 10, 12]
# 将多个有序列表合并成一个有序列表
merged_list = list(merge(list1, list2, list3))
# 输出合并后的有序列表
print(merged_list)
```
输出结果为:
```
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12]
```
在上面的代码中,我们使用了heapq模块中的merge()函数,将多个有序列表合并成一个有序列表,并使用list()函数将merge()函数返回的迭代器转换为列表。
相关问题
Python中merge的官方文档
你好,以下是Python中merge的官方文档说明:
函数签名:merge(iterables, key=None, reverse=False)
Docstring:
Merge multiple sorted inputs into a single sorted output.
Similar to sorted(itertools.chain(*iterables)) but returns an iterable,
does not pull the data into memory all at once, and assumes that each of the
input streams is already sorted (smallest to largest).
Key argument specifies a key function of one argument to extract a comparison key
from each element in the inputs. The key function defaults to an identity function
returning the element unchanged. If multiple items have the same key value,
the order in the output is undefined.
reverse = True will sort the iterable in descending order.
Usage:
merge(*iterables, key=None, reverse=False) --> generator
Example usage:
>>> list(merge([1, 3, 5], [2, 4, 6]))
[1, 2, 3, 4, 5, 6]
>>> list(merge([1, 3, 5], [2, 4, 6], reverse=True))
[6, 5, 4, 3, 2, 1]
以上是Python中merge的官方文档说明,希望这可以帮助您!
python使用哈夫曼吗压缩文本文件代码
是的,Python可以使用哈夫曼编码来压缩文本文件。可以使用Python内置的模块如`heapq`和`collections`来实现哈夫曼编码。以下是一个压缩文件的示例代码:
```python
import heapq
import os
class HuffmanCoding:
def __init__(self, path):
self.path = path
self.heap = []
self.codes = {}
self.reverse_mapping = {}
class HeapNode:
def __init__(self, char, freq):
self.char = char
self.freq = freq
self.left = None
self.right = None
def __lt__(self, other):
return self.freq < other.freq
def __eq__(self, other):
if(other == None):
return False
if(not isinstance(other, HeapNode)):
return False
return self.freq == other.freq
def make_frequency_dict(self, text):
frequency = {}
for character in text:
if not character in frequency:
frequency[character] = 0
frequency[character] += 1
return frequency
def make_heap(self, frequency):
for key in frequency:
node = self.HeapNode(key, frequency[key])
heapq.heappush(self.heap, node)
def merge_nodes(self):
while(len(self.heap)>1):
node1 = heapq.heappop(self.heap)
node2 = heapq.heappop(self.heap)
merged = self.HeapNode(None, node1.freq + node2.freq)
merged.left = node1
merged.right = node2
heapq.heappush(self.heap, merged)
def make_codes_helper(self, root, current_code):
if(root == None):
return
if(root.char != None):
self.codes[root.char] = current_code
self.reverse_mapping[current_code] = root.char
return
self.make_codes_helper(root.left, current_code + "0")
self.make_codes_helper(root.right, current_code + "1")
def make_codes(self):
root = heapq.heappop(self.heap)
current_code = ""
self.make_codes_helper(root, current_code)
def get_encoded_text(self, text):
encoded_text = ""
for character in text:
encoded_text += self.codes[character]
return encoded_text
def pad_encoded_text(self, encoded_text):
extra_padding = 8 - len(encoded_text) % 8
for i in range(extra_padding):
encoded_text += "0"
padded_info = "{0:08b}".format(extra_padding)
encoded_text = padded_info + encoded_text
return encoded_text
def get_byte_array(self, padded_encoded_text):
if(len(padded_encoded_text) % 8 != 0):
print("Encoded text not padded properly")
exit(0)
b = bytearray()
for i in range(0, len(padded_encoded_text), 8):
byte = padded_encoded_text[i:i+8]
b.append(int(byte, 2))
return b
def compress(self):
filename, file_extension = os.path.splitext(self.path)
output_path = filename + ".bin"
with open(self.path, 'r+') as file, open(output_path, 'wb') as output:
text = file.read()
text = text.rstrip()
frequency = self.make_frequency_dict(text)
self.make_heap(frequency)
self.merge_nodes()
self.make_codes()
encoded_text = self.get_encoded_text(text)
padded_encoded_text = self.pad_encoded_text(encoded_text)
b = self.get_byte_array(padded_encoded_text)
output.write(bytes(b))
print("Compressed")
return output_path
"""其他方法"""
```
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