openfile.py

#原始的方式

lines = [line.split(',') for line in open('iris.csv')]
df = [[float(x) for x in line[:4]] for line in lines[1:]]

#使用numpy包

import numpy as np
lines = np.loadtxt('iris.csv',delimiter=',',dtype='str')
df = lines[1:,:4].astype('float')

#使用pandas包

import pandas as pd
df = pd.read_csv('iris.csv')
df=df.ix[:,:4]