Introduction to file-related processing operations in Python (with code)

open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None)
参数说明:
file: 必需，文件路径（相对或者绝对路径）。
mode: 可选，文件打开模式
buffering: 设置缓冲
encoding: 一般使用utf8
errors: 报错级别
newline: 区分换行符
closefd: 传入的file参数类型
opener:

>>> with open('F://lixu.txt','r') as f:
...     print(f.read())
...
大家好，我叫李*！

>>> try:
...     f = open('F://lixu.txt',mode='r')
...     print(f.read())
... finally:
...     if f:
...         f.close()
...
大家好，我叫李*！

def readData(self,datafile = None):
        """
        read the data from the data file which is a data set
        """
        self.datafile = datafile or self.datafile
        self.data = []
        for line in open(self.datafile):
            userid,itemid,record,_ = line.split()
            self.data.append((userid,itemid,int(record)))

>>> with open('F://lixu.txt','r') as f:
...     print(f.read())
...
大家好，我叫李*！

文件内容：
1:www.runoob.com
2:www.runoob.com
3:www.runoob.com
4:www.runoob.com
5:www.runoob.com

# 打开文件
fo = open("runoob.txt", "rw+")
print "文件名为: ", fo.name

line = fo.readline()
print "读取第一行 %s" % (line)

line = fo.readline(5)
print "读取的字符串为: %s" % (line)

# 关闭文件
fo.close()

文件名为:  runoob.txt
读取第一行 1:www.runoob.com
读取的字符串为: 2:www

def file2matrix(filename):
    """
    从文件中读入训练数据，并存储为矩阵
    """
    fr = open(filename)
    arrayOlines = fr.readlines()
    numberOfLines = len(arrayOlines)   #获取 n=样本的行数
    returnMat = zeros((numberOfLines,3))   #创建一个2维矩阵用于存放训练样本数据，一共有n行，每一行存放3个数据
    classLabelVector = []    #创建一个1维数组用于存放训练样本标签。  
    index = 0
    for line in arrayOlines:
        # 把回车符号给去掉
        line = line.strip()    
        # 把每一行数据用\t分割
        listFromLine = line.split('\t')
        # 把分割好的数据放至数据集，其中index是该样本数据的下标，就是放到第几行
        returnMat[index,:] = listFromLine[0:3]
        # 把该样本对应的标签放至标签集，顺序与样本集对应。
        classLabelVector.append(int(listFromLine[-1]))
        index += 1
    return returnMat,classLabelVector

>>> f = open('F://lixu.txt',mode='r')
>>> line2 = f.readline()
>>> print(line2)
大家好，我叫李*！

>>> f = open('F://lixu.txt',mode='r')
>>> line = f.read()
>>> print(line)
大家好，我叫李*！

啦啦啦



>>> f = open('F://lixu.txt',mode='r')
>>> line = f.readlines()
>>> print(line)
['大家好，我叫李*！\n', '\n', '啦啦啦\n', '\n', '\n']