PYTHON将列表存储为csv文件以及从csv中提取数据

一、问题：从这个 https://blog.csdn.net/qq_42052864/article/details/81591511 中获得的灵感，但是我是要实现存储为2行n列的？怎么办呢？

import numpy as np
wab1 = [1,2,3,4,5,6,7]
wab2 = [7,6,5,4,3,2,1]

np.savetxt('new.csv',wab2, delimiter = ',') 

#结果：new.csv
7.00E+00
6.00E+00
5.00E+00
4.00E+00
3.00E+00
2.00E+00
1.00E+00

解决方法1：那我在存储一次不就行了？

import numpy as np
wab1 = [1,2,3,4,5,6,7]
wab2 = [7,6,5,4,3,2,1]

np.savetxt('new.csv',wab1, delimiter = ',') 

#结果：new.csv
1.00E+00
2.00E+00
3.00E+00
4.00E+00
5.00E+00
6.00E+00
7.00E+00   #被覆盖了，哈哈，以失败告终

 

解决方法2：np.array(my_matrix).reshape(7,2)

到后面才发现这个np.array是将将每个元素按顺序拿出来，然后重新行排列为想要的m*n

那么我们将两个列表交叉插入后就可以存储了，试试吧！

import numpy as np
wab1 = [1,2,3,4,5,6,7]
wab2 = [7,6,5,4,3,2,1]

list2 = []
for (i,j) in zip(wab1,wab2):
    list2.append(i)
    list2.append(j)
print(list2)
a = np.array(list2).reshape(7,2)

print(a)
np.savetxt('new.csv',a, delimiter = ',')

#output
[1, 7, 2, 6, 3, 5, 4, 4, 5, 3, 6, 2, 7, 1]
[[1 7]
 [2 6]
 [3 5]
 [4 4]
 [5 3]
 [6 2]
 [7 1]]

#new.csv
1.00E+00    7.00E+00
2.00E+00    6.00E+00
3.00E+00    5.00E+00
4.00E+00    4.00E+00
5.00E+00    3.00E+00
6.00E+00    2.00E+00
7.00E+00    1.00E+00

这样就可以了啊！嘻嘻！

 

中途遇到的小问题：

import numpy as np
wab1 = [1,2,3,4,5,6,7]
wab2 = [7,6,5,4,3,2,1]
    
#转换成列
Wab1 = np.array(wab1).reshape(-1,1)
Wab2 = np.array(wab2).reshape(-1,1)


my_matrix = [Wab1,Wab2] #这是一个矩阵7*1*2，不是 7*2 的

 

二。提取数据：

csv文件是这么操作的:

b = np.loadtxt(open("new.csv","rb"),delimiter=",",skiprows=0)
print(b)

#结果：
[[1. 7.]
 [2. 6.]
 [3. 5.]
 [4. 4.]
 [5. 3.]
 [6. 2.]
 [7. 1.]]

txt文件如下：

np.savetxt('new.txt',a, delimiter = ',')
c = np.loadtxt('new.txt',delimiter=",")
print(c)

#结果：
[[1. 7.]
 [2. 6.]
 [3. 5.]
 [4. 4.]
 [5. 3.]
 [6. 2.]
 [7. 1.]]

#new.txt
1.000000000000000000e+00,7.000000000000000000e+00
2.000000000000000000e+00,6.000000000000000000e+00
3.000000000000000000e+00,5.000000000000000000e+00
4.000000000000000000e+00,4.000000000000000000e+00
5.000000000000000000e+00,3.000000000000000000e+00
6.000000000000000000e+00,2.000000000000000000e+00
7.000000000000000000e+00,1.000000000000000000e+00

 

三、如果遇到这个（请把csv文件关闭）：

Traceback (most recent call last):
  File "C:\Users\Administrator\Desktop\矩阵导入csv导入数据-实验\import-data-exp.py", line 13, in <module>
    np.savetxt('new.csv',a, delimiter = ',')
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python37-32\lib\site-packages\numpy\lib\npyio.py", line 1359, in savetxt
    open(fname, 'wt').close()
PermissionError: [Errno 13] Permission denied: 'new.csv'

四、参考：

https://blog.csdn.net/vernice/article/details/50683637

https://blog.csdn.net/weixin_43593330/article/details/89882187?depth_1-utm_source=distribute.pc_relevant.none-task&utm_source=distribute.pc_relevant.none-task