將列添加到二維數組

Question

我正在逐個讀取多個.csv文件，取一列並將這些列累積到一個數組中，最後想要將一個.csv文件從中取出。

enter code here 
import numpy as np 
import matplotlib.pyplot as plt 
import os, os.path 
for root, dirs, files in os.walk('C:\\Users\\me\\Desktop\\csvfiles'): 
    for f in files: 
    fullpath = os.path.join(root, f) 
    if os.path.splitext(fullpath)[1] == '.csv': 
     data = np.genfromtxt(fullpath, delimiter=',',names=['A', 'B', 'C', 'D']) 
     col_sel = np.array(data['B']) 
     col_sel = np.hstack([col_sel]) 
    np.savetxt('test.csv', col_sel, delimiter=',') 

不知何故，這不是將數據添加到列向列陣。如果這一切有效，其他一切可能都會落實到位有人能告訴我爲什麼嗎？

Answer 1

如果要垂直堆疊他們和他們在一個二維數組寫在最後列的數目等於CVS文件：

import numpy as np 
import matplotlib.pyplot as plt 
import os, os.path 
n=0 
for root, dirs, files in os.walk('/users/test'): 
    for f in files: 
    fullpath = os.path.join(root, f) 
    if os.path.splitext(fullpath)[1] == '.csv': 
     data = np.genfromtxt(fullpath, delimiter=',',names=['A', 'B', 'C', 'D']) 
     if(n==0): 
      col_sel = data['B'] 
     else: 
      col_sel = np.vstack((col_sel,data['B'])) 
     n+=1 
np.savetxt('/users/test.csv', col_sel, delimiter=',')