在循环中将项添加到数组

Question

我尝试在循环中向numpy.array添加一行，虽然我没有收到任何错误但它仍无法正常工作。我的总体目标是比较两个文件并创建第三个文件，总结比较。

ipython

import numpy as np

我的数组

aList1=np.array([['A','we'],['A','we'],['B','we'],['C','de']])
aList2=np.array([['A'],['B'],['D']])
aResult=np.array(['row1','occurence'])

我的功能

def coverageA(array,file1,name1,colum1,file2,name2,colum2):
     x=file1[1:,colum1]
     y=file2[1:,colum2]
     for f in x:
         if f in y:
             array=np.vstack((array,np.array([f,'shared'])))
         else:
             array=np.vstack((array,np.array([f,name1])))
     for f in y:
         if f not in x:
             array=np.vstack((array,np.array([f,name2])))
     return

并以这种方式使用

coverageA(aResult,alist1,'list1', 0,aList2,'list',0)

但aResult没有改变

print(aResult) output:(['row1','occurence'])

想

([['row1','occurence'],['A', 'shared'],['B', 'shared'],['C','list1'],['D','list2']])

Answer 1

<强>修复

import numpy as np

#my arrays

aList1=np.array([['A','we'],['A','we'],['B','we'],['C','de']])
aList2=np.array([['A'],['B'],['D']])
aResult=np.array(['row1','occurence'])

#my function

def coverageA(array,file1,name1,colum1,file2,name2,colum2):
    x=file1[1:,colum1]
    y=file2[1:,colum2]
    for f in x:
        if f in y:
            array=np.vstack((array,np.array([f,'shared'])))
        else:
            array=np.vstack((array,np.array([f,name1])))
    for f in y:
        if f not in x:
            array=np.vstack((array,np.array([f,name2])))
    print(array)
    return array

#and use it this way

aResult=coverageA(aResult,aList1,'list1', 0,aList2,'list2',0)
#but aResult didn't change

print(aResult) 
#output:(['row1','occurence'])
#wanted

#([['row1','occurence'],['A', 'shared'],['B', 'shared'],['C','list1'],['D','list2']])

解释是，在python参数中通过赋值传递，这很好地解释了here。在行array=np.vstack((array,np.array([f,'shared'])))中，在新的存储器内存中创建了一个新的numpy数组（数组指向此），但aResult仍指向其旧位置。您可以使用print(id(array))检查内存地址。