Python_file_test7_190616

最新推荐文章于 2023-08-07 21:51:04 发布

Daria·Saira

最新推荐文章于 2023-08-07 21:51:04 发布

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分类专栏： Python OJ trick

本文链接：https://blog.youkuaiyun.com/qq_38985700/article/details/92199414

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本文深入探讨了Python中文件读写的各种方法，包括按字符读取、按行读取和逆序读取等，同时展示了如何使用字符串方法处理数据，如去除换行符、反转字符串和分割字符串。此外，还介绍了如何利用集合去重来计算文件中独特行的数量。

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conclusion

oj 1 重复行的题好玩
join : join() 方法用于将序列中的元素以指定的字符连接生成一个新的字符串。

str.join(sequence)
ls.remove()可以去掉某一个元素(一次)，如果该行是独特行，去掉该元素后将不在集合t中出现。
file_method

file
file.read()
file.readlines()

#coding:utf-8
f=open('D:/workspace/python/source/data.csv')
print(f)
print("-------------")
print(f.read())#read base on char & point at the end

f.seek(0)
print("-------------")
for char in f.read(5):
    print(char)
f.seek(0)#put point to the beginning 
print("-------------")
lines=f.readlines()#read base on column
# line = line.strip("\n")
# ls = line.split(",") 
print(lines)
print("-------------")
for line in lines:
    line=line[::-1]
    line=line.replace('\n','')
    print(line)

f.seek(0)
print("-------------")
for line in f:
    #in essence realize the method file.readlines()
    print(line)#with \n
    line = line.strip("\n")#drop out \n
    print(line)
    ls = line.split(",")
    #divide item by ',' and print with type list
    print(ls)
    ls = ls[::-1]
    print(",".join(ls)) #print with correct format(str) 
f.close()

<_io.TextIOWrapper name='D:/workspace/python/source/data.csv' mode='r' encoding='cp936'>
-------------
1,2,3,4,5,6,7
8, 3, 2, 7, 1, 4, 6, 5
6, 1, 3, 8, 5, 7, 4, 2
'a','b','c','x','y','z','i','j','k'
'k', 'b', 'j', 'c', 'i', 'y', 'z', 'a', 'x'
'z', 'c', 'b', 'a', 'k', 'i', 'j', 'y', 'x'
'a', 'y', 'b', 'x', 'z', 'c', 'i', 'j', 'k'
5, 2, 4, 7, 1, 6, 8, 3
-------------
1
,
2
,
3
-------------
['1,2,3,4,5,6,7\n', '8, 3, 2, 7, 1, 4, 6, 5\n', '6, 1, 3, 8, 5, 7, 4, 2\n', "'a','b','c','x','y','z','i','j','k'\n", "'k', 'b', 'j', 'c', 'i', 'y', 'z', 'a', 'x'\n", "'z', 'c', 'b', 'a', 'k', 'i', 'j', 'y', 'x'\n", "'a', 'y', 'b', 'x', 'z', 'c', 'i', 'j', 'k'\n", '5, 2, 4, 7, 1, 6, 8, 3']
-------------
7,6,5,4,3,2,1
5 ,6 ,4 ,1 ,7 ,2 ,3 ,8
2 ,4 ,7 ,5 ,8 ,3 ,1 ,6
'k','j','i','z','y','x','c','b','a'
'x' ,'a' ,'z' ,'y' ,'i' ,'c' ,'j' ,'b' ,'k'
'x' ,'y' ,'j' ,'i' ,'k' ,'a' ,'b' ,'c' ,'z'
'k' ,'j' ,'i' ,'c' ,'z' ,'x' ,'b' ,'y' ,'a'
3 ,8 ,6 ,1 ,7 ,4 ,2 ,5
-------------
1,2,3,4,5,6,7

1,2,3,4,5,6,7
['1', '2', '3', '4', '5', '6', '7']
7,6,5,4,3,2,1
8, 3, 2, 7, 1, 4, 6, 5

8, 3, 2, 7, 1, 4, 6, 5
['8', ' 3', ' 2', ' 7', ' 1', ' 4', ' 6', ' 5']
 5, 6, 4, 1, 7, 2, 3,8
6, 1, 3, 8, 5, 7, 4, 2

6, 1, 3, 8, 5, 7, 4, 2
['6', ' 1', ' 3', ' 8', ' 5', ' 7', ' 4', ' 2']
 2, 4, 7, 5, 8, 3, 1,6
'a','b','c','x','y','z','i','j','k'

'a','b','c','x','y','z','i','j','k'
["'a'", "'b'", "'c'", "'x'", "'y'", "'z'", "'i'", "'j'", "'k'"]
'k','j','i','z','y','x','c','b','a'
'k', 'b', 'j', 'c', 'i', 'y', 'z', 'a', 'x'

'k', 'b', 'j', 'c', 'i', 'y', 'z', 'a', 'x'
["'k'", " 'b'", " 'j'", " 'c'", " 'i'", " 'y'", " 'z'", " 'a'", " 'x'"]
 'x', 'a', 'z', 'y', 'i', 'c', 'j', 'b','k'
'z', 'c', 'b', 'a', 'k', 'i', 'j', 'y', 'x'

'z', 'c', 'b', 'a', 'k', 'i', 'j', 'y', 'x'
["'z'", " 'c'", " 'b'", " 'a'", " 'k'", " 'i'", " 'j'", " 'y'", " 'x'"]
 'x', 'y', 'j', 'i', 'k', 'a', 'b', 'c','z'
'a', 'y', 'b', 'x', 'z', 'c', 'i', 'j', 'k'

'a', 'y', 'b', 'x', 'z', 'c', 'i', 'j', 'k'
["'a'", " 'y'", " 'b'", " 'x'", " 'z'", " 'c'", " 'i'", " 'j'", " 'k'"]
 'k', 'j', 'i', 'c', 'z', 'x', 'b', 'y','a'
5, 2, 4, 7, 1, 6, 8, 3
5, 2, 4, 7, 1, 6, 8, 3
['5', ' 2', ' 4', ' 7', ' 1', ' 6', ' 8', ' 3']
 3, 8, 6, 1, 7, 4, 2,5

OJ practice example

main idea : 重复行(多行)和独特行(单行)对 去重后行数 贡献度 均为 1
		    删除独特行后仅剩重复行贡献度,贡献度差值即为number of unique

          set()=3     after remove    set()=1 =>  **unique =3-1=2**
333                            
333  ----> 333   =>     333             333
333      
2    ----> 2            null                
1    ----> 1            null

#coding:utf-8
#统计附件文件中与其他任何其他行都不同的行的数量，
#即独特行的数量。
f=open("D:/workspace/python/source/123.txt")
txt=f.readlines()
a=set(txt)#no repetition text
#! but not unique line set 
for i in a:
    txt.remove(i)
    #ls.remove()可以去掉某一个元素，如果该行是独特行，去掉该元素后将不在集合t中出现。
clear=set(txt)
print("去重后行数(非独特行){}行".format(len(a)))
print("共{}独特行".format(len(a)-len(clear)))

去重后行数(非独特行)18行
共12独特行

#coding:utf-8
#统计附件文件中与其他任何其他行都不同的行的数量，
#即独特行的数量。
f=open("D:/workspace/python/source/123.txt")
txt=f.readlines()
a=set(txt)#no repetition text
#! but not unique line set 
for i in a:
    txt.remove(i)
    #ls.remove()可以去掉某一个元素，如果该行是独特行，去掉该元素后将不在集合t中出现。
clear=set(txt)
print("共{}独特行".format(len(a)-len(clear)))

#coding:utf-8

f=open("C:/Users/UMR/Desktop/123.txt","rt")
lines=f.readlines()#test find read with the space ('\n')
lines.reverse()
#print(f)
#print(lines)
for line in lines:
    line=line.replace('\n','')
    #print(line)
    line=line.split(',')
    line=line[::-1]
    print(';'.join(line))

<_io.TextIOWrapper name='C:/Users/UMR/Desktop/123.txt' mode='rt' encoding='cp936'>
['7,8,9\n', '4,5,6\n', '1,2,3\n']
7,8,9
9;8;7
4,5,6
6;5;4
1,2,3
3;2;1
--------------------------------
9;8;7
6;5;4
3;2;1

#coding:utf-8
f1=open("C:/Users/UMR/Desktop/123.txt","rt")
row=0
col=0
lines1=f1.readlines()#print in type list
print(lines1)
f1.seek(0)
for line in f1:#print in type str
    print(line)
    if len(line) != 1 and line[-1] =='\n':#value+\n at least 2
        row+=1
        col+=len(line)-1#discard the '\n'
print(int(col/row+0.5))#rounding off (四舍五入)

['1,2,3\n', '4,5,6\n', '7,8,9\n']
1,2,3

4,5,6

7,8,9

5