python两个列表合并

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本文介绍了如何使用Python将两个包含共同key的列表合并，当key不存在于其中一个列表时，用0填充缺失的值。通过示例代码展示了具体的合并过程，最终得到了期望的合并结果。

// python 两个列表合并

# by coco

# 20151231

需求是这样的：我有2个列表 ,其中列表中有一个公共key, 我想按照最长的公共key 合并这2个列表，没有值的补0 。如下例子：

a = [{"dateinfo":"20151220","pro_num":"100"}]

b= [{"dateinfo":"20151220","sep_num":"200"},{"dateinfo":"20151221","sep_num":"300"},{"dateinfo":"20151222","sep_num":"300"}]

最终我想要的合并列表结果如下：

c= [{"dateinfo":"20151220","sep_num":"200","pro_num":"100"},{"dateinfo":"20151221","sep_num":"300","pro_num":"0"},{"dateinfo":"20151222","sep_num":"300","pro_num":"0"}]

代码如下：

a = [{"dateinfo":"20151220","pro_num":"100"}]
{"20151220":"100"}
b= [{"dateinfo":"20151220","sep_num":"200"},{"dateinfo":"20151221","sep_num":"300"},{"dateinfo":"20151222","sep_num":"300"}]
#最终我想要的合并列表结果如下：
#c=  [{"dateinfo":"20151220","sep_num":"200","pro_num":"100"},{"dateinfo":"20151221","sep_num":"300","pro_num":"0"},{"dateinfo":"20151222","sep_num":"300","pro_num":"0"}]

#print a ,b
key_list = []
new_a = []
c = []
for i in b:
    dateinfo = i["dateinfo"]
    key_list.append(dateinfo)

print key_list
#想把a列表补齐 公共key 缺失的项目：
new_a=[({"dateinfo":i,"pro_num":0  if i not in dict([ j.values()  for  j in a ]).keys()  else dict([ j.values()  for  j in a ])[i] })         for i in key_list]
print new_a

#合并 new_a,b列表，组合成所需要的新列表c
c = [dict(i,**j)  for i,j in zip (new_a,b)]
print c

结果如下：

/System/Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7 /Users/coco/PycharmProjects/pyscript/py_test.py
['20151220', '20151221', '20151222']
[{'dateinfo': '20151220', 'pro_num': '100'}, {'dateinfo': '20151221', 'pro_num': 0}, {'dateinfo': '20151222', 'pro_num': 0}]
[{'dateinfo': '20151220', 'sep_num': '200', 'pro_num': '100'}, {'dateinfo': '20151221', 'sep_num': '300', 'pro_num': 0}, {'dateinfo': '20151222', 'sep_num': '300', 'pro_num': 0}]

Process finished with exit code 0