9.Python读取-写入文本文件

1.读取文本文件 

vi file_to_read.txt 
I'm 
already 
much 
better 
at
Python 


vi first_script.py 
import sys 
input_file=sys.argv[1]    #第二个传输参数
filereader=open(input_file,'r')  #读取方式打开
for row in filereader:
	print(row.strip())
filereader.close() 

#结果 
[root@mysql51 ~]# python first_script.py file_to_read.txt 
I'm
already
much
better
at
Python

[root@mysql51 ~]# python first_script.py "/root/file_to_read.txt" 
I'm
already
much
better
at
Python

2.读取文件的新型语法

#with open(input_file,'r',newline='') as filereader: (语法错误) 
#修改为:with open(input_file,'rb') as filereader: 
import sys 
from math import exp,log,sqrt 
import re 
from datetime import date,time,datetime,timedelta 
from operator import itemgetter 
input_file=sys.argv[1]
with open(input_file,'rb') as filereader:   #newline无法识别,语法错误
	for row in filereader:
		print("{}".format(row.strip()))

#结果 
[root@mysql51 ~]# python first_script.py "/root/file_to_read.txt" 
I'm
already
much
better
at
Python

3.使用glob读取多个文本文件

vi another_file_to_read.txt 
This 
text 
comes 
from 
a 
differenct 
text 
file.

 
vi first_script.py 
#encoding:utf-8
#导入os 模块使用 os.path.join 
from math import exp,log,sqrt 
import re 
from datetime import date,time,datetime,timedelta 
from operator import itemgetter 
import sys 
import glob 
import os 
inputPath=sys.argv[0]
for input_file in glob.glob(os.path.join(inputPath,'*.txt')):
	with open(input_file,'rb') as filereader: 
		for row in filereader: 
			print("{}".format(row.strip()))
			
#结果 
[root@mysql51 python_scripts]# python first_script2.py /root/python_scripts/
I'm
already
much
better
at
Python
This
text
comes
from
a
differenct
text
file.
[root@mysql51 python_scripts]# ll
total 16
-rw-r--r--. 1 root root  52 Mar 11 13:58 another_file_to_read.txt
-rw-r--r--. 1 root root  39 Mar 11 13:39 file_to_read.txt
-rw-r--r--. 1 root root 367 Mar 11 14:02 first_script2.py
-rw-r--r--. 1 root root 275 Mar 11 13:52 first_script.py

4.将结果写入到文件中。

#encoding:utf-8
from math import exp,log,sqrt 
import re 
from datetime import date,time,datetime,timedelta 
from operator import itemgetter 
import sys 
import glob 
import os 
my_letters=['a','b','c','d','e','f','g','h','i','j']
max_index=len(my_letters)
output_file=sys.argv[1]
filewriter=open(output_file,'w')
for index_value in range(len(my_letters)):
	if index_value<(max_index-1):
		filewriter.write(my_letters[index_value]+'\t')  #没到最后就输入制表符
	else:
		filewriter.write(my_letters[index_value]+'\n')  #到了末尾就回车
filewriter.close() 
print("Output written to file")

#结果 
[root@mysql51 python_scripts]# python first_script.py /root/python_scripts/file_to_write.txt
Output written to file
[root@mysql51 python_scripts]# more file_to_write.txt
a	b	c	d	e	f	g	h	i	j

5.写入CSV文件

vi first_script3.py
#encoding:utf-8
from math import exp,log,sqrt 
import re 
from datetime import date,time,datetime,timedelta 
from operator import itemgetter 
import sys 
import glob 
import os 
my_numbers=[0,1,2,3,4,6,6,7,8,9]
max_index=len(my_numbers)
output_file=sys.argv[1]
filewriter=open(output_file,'a')   #a 追加模式,r 读取模式,w 写入模式 
for index_value in range(len(my_numbers)):
	if index_value<(max_index-1):  #出来最后一位。
		filewriter.write(str(my_numbers[index_value])+',')  #未到末尾写逗号
	else: 
		filewriter.write(str(my_numbers[index_value])+'\n') #最后一个后面写回车 
filewriter.close() 
print("Output appended to file")

#结果 
[root@mysql51 python_scripts]# python first_script3.py first_script3.out 
Output appended to file
[root@mysql51 python_scripts]# 
[root@mysql51 python_scripts]# 
[root@mysql51 python_scripts]# more first_script3.out 
0,1,2,3,4,6,6,7,8,9

6.总结

输入文件名需要sys模块。导入sys后可以使用argv[0]等表示参数。