我试图处理保存在CSV中的数据,这些数据可能在未知数量的列(最多约30列)中缺少值。我试图使用genfromtxt
的filling_missing
参数将这些缺失的值设置为“0”。以下是针对在Win 7上运行的ActiveState ActivePython 2.7 32位中numpy 1.6.2的最小工作示例。
import numpy
text = "a,b,c,d\n1,2,3,4\n5,,7,8"
a = numpy.genfromtxt('test.txt',delimiter=',',names=True)
b = open('test.txt','w')
b.write(text)
b.close()
a = numpy.genfromtxt('test.txt',delimiter=',',names=True)
print "plain",a
a = numpy.genfromtxt('test.txt',delimiter=',',names=True,filling_values=0)
print "filling_values=0",a
a = numpy.genfromtxt('test.txt',delimiter=',',names=True,filling_values={1:0})
print "filling_values={1:0}",a
a = numpy.genfromtxt('test.txt',delimiter=',',names=True,filling_values={0:0})
print "filling_values={0:0}",a
a = numpy.genfromtxt('test.txt',delimiter=',',names=True,filling_values={None:0})
print "filling_values={None:0}",a
结果如下:
plain [(1.0, 2.0, 3.0, 4.0) (5.0, nan, 7.0, 8.0)]
filling_values=0 [(1.0, 2.0, 3.0, 4.0) (5.0, nan, 7.0, 8.0)]
filling_values={1:0} [(1.0, 2.0, 3.0, 4.0) (5.0, 0.0, 7.0, 8.0)]
filling_values={0:0} [(1.0, 2.0, 3.0, 4.0) (5.0, nan, 7.0, 8.0)]
Traceback (most recent call last):
File "C:\Users\tolivo.EE\Documents\active\eng\python\sizer\testGenfromtxt.py", line 20, in <module>
a = numpy.genfromtxt('test.txt',delimiter=',',names=True,filling_values={None:0})
File "C:\Users\tolivo.EE\AppData\Roaming\Python\Python27\site-packages\numpy\lib\npyio.py", line 1451, in genfromtxt
filling_values[key] = val
TypeError: list indices must be integers, not NoneType
从NumPy用户指南中,我期望
filling_values=0
和filling_values={None:0}
可以正常工作,但实际上它们不起作用,并分别抛出错误。当你指定正确的列(filling_values={1:0}
)时,它可以工作,但由于我有大量未知数量的列在用户选择之前,我正在寻找一种自动设置填充值的方法,就像用户指南所提示的那样。我想我可能可以提前计算列数并创建一个字典作为填充值传递,但是否有更好的方法?