Python-“无法使用灵活类型执行归约"尝试使用numpy.mean时 [英] Python - "cannot perform reduce with flexible type" when trying to use numpy.mean
问题描述
我精疲力尽,因为当我尝试计算列的平均值时,我不断收到无法使用弹性类型执行归约"的操作,文件读取得很好(任何行/列中都没有缺失值)但是当我加入以下内容时: Brain_wt_mean = np.mean(ifile axis = 0),那么Python 2.7.5不喜欢它.我在Spyder IDE中使用它.非常感谢您的帮助.
I'm at my wit's end as I keep getting "cannot perform reduce with flexible type" when I try to compute the mean of a column, the file is read in just fine (no missing values in any rows/column) but when I put in the line: Brain_wt_mean = np.mean(ifile axis=0) then Python 2.7.5 does not like it. I am using this within the Spyder IDE. Thanks much for any help.
import os
import numpy as np
if __name__ == "__main__":
try:
curr_dir = os.getcwd()
file_path = curr_dir + '\\brainandbody.csv'
ifile = np.loadtxt('brainandbody.csv', delimiter=',', skiprows=1, dtype=[('brainwt', 'f8'), ('bodywt', 'f8')])
except IOError:
print "The file does not exist, exiting gracefully"
Brain_wt_mean = np.mean(ifile axis=0)
### BELOW is a sample of the csv file ######
Brain Weight Body Weight
3.385 44.5
0.48 15.5
1.35 8.1
465 423
36.33 119.5
27.66 115
14.83 98.2
1.04 5.5
推荐答案
在使用结构化数组时,您将失去原本会拥有的一些灵活性.不过,您可以在选择适当的片段后取均值:
When you're working with structured arrays like that you lose some of the flexibility you'd otherwise have. You can take the mean after selecting the appropriate piece, though:
>>> ifile
array([(3.385, 44.5), (0.48, 15.5), (1.35, 8.1), (465.0, 423.0),
(36.33, 119.5), (27.66, 115.0), (14.83, 98.2), (1.04, 5.5)],
dtype=[('brainwt', '<f8'), ('bodywt', '<f8')])
>>> ifile["brainwt"].mean()
68.759375000000006
>>> ifile["bodywt"].mean()
103.66249999999999
我几乎每天都使用numpy
,但是在处理我想为列命名的数据时,我认为 pandas
库使事情变得更加方便,并且可以很好地互操作.值得一看.示例:
I use numpy
almost every day, but when working with data of the sort where I want to name columns, I think the pandas
library makes things much more convenient, and it interoperates very well. It's worth a look. Example:
>>> import pandas as pd
>>> df = pd.read_csv("brainandbody.csv", skipinitialspace=True)
>>> df
Brain Weight Body Weight
0 3.385 44.5
1 0.480 15.5
2 1.350 8.1
3 465.000 423.0
4 36.330 119.5
5 27.660 115.0
6 14.830 98.2
7 1.040 5.5
>>> df.mean()
Brain Weight 68.759375
Body Weight 103.662500
dtype: float64
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