学习笔记5—Python 将多维数据转为一维数组 （总结）

<code class="language-python">import operator
from functools import reduce
a = [[1,2,3], [4,6], [7,8,9,8]]
print(reduce(operator.add, a))
[1, 2, 3, 4, 6, 7, 8, 9, 8]</code>

1. a = [[1,2,3], [5, 8], [7,8,9]]
2. l=[]
3. for m in range(0,3):
4. for i in a[m]:
5. l.append(i)
6. print(l)
7. [1, 2, 3, 5, 8, 7, 8, 9]

1. from itertools import chain
2. b=[[1,2,3], [5,8], [7,8,9]]
3. c=list(chain(*b))
4. print(c)
5. [1, 2, 3, 5, 8, 7, 8, 9]

1. a=[[1,2,3], [5,8], [7,8,9]]
2. a= eval('['+str(a).replace(' ','').replace('[','').replace(']','')+']')
3. print(a)
4. [1, 2, 3, 5, 8, 7, 8, 9]

1. def flatten(a):
2. if not isinstance(a, (list, )):
3. return [a]
4. else:
5. b = []
6. for item in a:
7. b += flatten(item)
8. return b

1. if __name__ == '__main__':
2. a = [[[1,2],3],[4,[5,6]],[7,8,9]]
3. print(flatten(a))
4. [1, 2, 3, 4, 5, 6, 7, 8, 9]

1. ab = [[1,2,3], [5,8], [7,8,9]]
2. print([i for item in ab for i in item])
3. [1, 2, 3, 5, 8, 7, 8, 9]

2、矩阵转数组：data = [[1,2,3,]] 去掉外层----> data = data[0,:]--->[1,2,3]

3、数组：data = [[1],[2]] ---> data = data.flatten() ---> [1,2]

4、列表：list = [[1],[2]] ---> list1 = [x for [x] in list] ---> list1 = [1,2]

5、将dataframe转成list：  data = np.array(data).tolist() （先将dataframe转成矩阵，再将矩阵转成list）