IndexError: too many indices for array

在练习机器学习的时候遇到了一个小问题，花费了挺长时间，故记录下
源码

from numpy import *
def file2matrix(filename):
    fr = open(filename)
    arrayOLines = fr.readlines()
    numberOFLines = len(arrayOLines)
    returnMat = zeros(numberOFLines)
    classLabelVector = []
    index = 0
    for line in arrayOLines:
        line = line.strip()
        listFromLine = line.split('\t')
        returnMat[index,:] = listFromLine[0:3]
        classLabelVector.append(int(listFromLine[-1]))
        index+=1
    return returnMat, classLabelVector

file2matrix('datingTestSet2.txt')

运行报错：IndexError: too many indices for array
在百度上找了半天错误，咋就索引太多了呢，索引多还不行了？然后在stackoverflow上看到了另一个人也遇到了这个错误，有大神在下面评论

You are getting this error because you are making target array ‘y’ 2-D which is actually needed to be 1-D to pass in cross validation function.
These two cases are different:
1. y=numpy.zeros(shape=(len(list),1))
2. y=numpy.zeros(shape=(len(list)))

果然问题在这里，初始化数组是一维的，应该是二维的（照着代码打都会错，汗！）将returnMat = zeros(numberOFLines)改成returnMat = zeros((numberOFLines,3))就OK了