loadtxt()函數的糟心歷程

原計划：導入一個csv文件，然后算出平均值

 

import numpy as np

 

c=np.loadtxt('d:\python36\data.csv', delimiter=',', usecols=(2,), unpack=True)

 

print ("median =", np.median(c))

 

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報錯：OSerror: d:\python36\data.csv not found

 

找了半天原因：原來是data.csv應該是data_1.csv

 

 

 

后來以為編碼問題

 

import numpy as np

 

import codecs

 

myfile='d:\python36\data_1.csv'

 

filecp = codecs.open(myfile, encoding='utf-8')

 

c=np.loadtxt(filecp, skiprows=2,dtype=int)

 

print ("median =", np.median(c))

 

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報錯：ValueError:  could not convert string to float:’12,1,2,12’

 

搞了半天，沒找到原因

 

去掉dtype=int后，報錯IndexError:list index out of range

 

 

最終：

 

import numpy as np

 

import codecs

 

myfile='d:\python36\data_1.csv'

 

filecp = codecs.open(myfile, encoding='utf-8')

 

c=np.loadtxt(filecp, skiprows=2,delimiter=’,’, usecols=(2,),dtype=float)

 

print ("median =", np.median(c))

 

 

 

搞定，IndexError問題出在delimiter=’,’；而ValueError問題出在dtype=int和delimiter=’,’，因為沒有delimiter=’,’隔開，就沒法轉換數據類型