假设我有一个包含以下内容的文本文件：
Dan
Warrior
500
1
0
有没有办法可以编辑该文本文件中的特定行？现在我有这个：
#!/usr/bin/env python
import io
myfile = open('stats.txt', 'r')
dan = myfile.readline()
print dan
print "Your name: " + dan.split('\n')[0]
try:
myfile = open('stats.txt', 'a')
myfile.writelines('Mage')[1]
except IOError:
myfile.close()
finally:
myfile.close()
是的，我知道myfile.writelines('Mage')[1]不正确。但是你明白了我的观点吧？我正在尝试用Mage替换Warrior来编辑第2行。但我能做到吗？
答案 0 :(得分：78)
你想做这样的事情：
# with is like your try .. finally block in this case
with open('stats.txt', 'r') as file:
# read a list of lines into data
data = file.readlines()
print data
print "Your name: " + data[0]
# now change the 2nd line, note that you have to add a newline
data[1] = 'Mage\n'
# and write everything back
with open('stats.txt', 'w') as file:
file.writelines( data )
原因是您不能直接在文件中执行“更改第2行”之类的操作。您只能覆盖（而不是删除）文件的某些部分 - 这意味着新内容仅涵盖旧内容。所以，如果你在第2行写“Mage”，那么结果就是'Mageior'。
答案 1 :(得分：18)
您可以使用fileinput进行就地编辑
import fileinput
for line in fileinput.FileInput("myfile", inplace=1):
if line .....:
print line
答案 2 :(得分：15)
def replace_line(file_name, line_num, text):
lines = open(file_name, 'r').readlines()
lines[line_num] = text
out = open(file_name, 'w')
out.writelines(lines)
out.close()
然后：
replace_line('stats.txt', 0, 'Mage')
答案 3 :(得分：2)
如果您的文字只包含一个人：
import re
# creation
with open('pers.txt','wb') as g:
g.write('Dan \n Warrior \n 500 \r\n 1 \r 0 ')
with open('pers.txt','rb') as h:
print 'exact content of pers.txt before treatment:\n',repr(h.read())
with open('pers.txt','rU') as h:
print '\nrU-display of pers.txt before treatment:\n',h.read()
# treatment
def roplo(file_name,what):
patR = re.compile('^([^\r\n]+[\r\n]+)[^\r\n]+')
with open(file_name,'rb+') as f:
ch = f.read()
f.seek(0)
f.write(patR.sub('\\1'+what,ch))
roplo('pers.txt','Mage')
# after treatment
with open('pers.txt','rb') as h:
print '\nexact content of pers.txt after treatment:\n',repr(h.read())
with open('pers.txt','rU') as h:
print '\nrU-display of pers.txt after treatment:\n',h.read()
如果您的文字包含多个人：
导入重新
# creation
with open('pers.txt','wb') as g:
g.write('Dan \n Warrior \n 500 \r\n 1 \r 0 \n Jim \n dragonfly\r300\r2\n10\r\nSomo\ncosmonaut\n490\r\n3\r65')
with open('pers.txt','rb') as h:
print 'exact content of pers.txt before treatment:\n',repr(h.read())
with open('pers.txt','rU') as h:
print '\nrU-display of pers.txt before treatment:\n',h.read()
# treatment
def ripli(file_name,who,what):
with open(file_name,'rb+') as f:
ch = f.read()
x,y = re.search('^\s*'+who+'\s*[\r\n]+([^\r\n]+)',ch,re.MULTILINE).span(1)
f.seek(x)
f.write(what+ch[y:])
ripli('pers.txt','Jim','Wizard')
# after treatment
with open('pers.txt','rb') as h:
print 'exact content of pers.txt after treatment:\n',repr(h.read())
with open('pers.txt','rU') as h:
print '\nrU-display of pers.txt after treatment:\n',h.read()
如果个人的“工作”在短信中具有恒定的长度，则您只能更改与所需个人的“工作”相对应的texte部分： 这和发送者的想法是一样的。
但据我所知，更好的方法是将个人的特征记录在cPickle文件中的字典中：
from cPickle import dump, load
with open('cards','wb') as f:
dump({'Dan':['Warrior',500,1,0],'Jim':['dragonfly',300,2,10],'Somo':['cosmonaut',490,3,65]},f)
with open('cards','rb') as g:
id_cards = load(g)
print 'id_cards before change==',id_cards
id_cards['Jim'][0] = 'Wizard'
with open('cards','w') as h:
dump(id_cards,h)
with open('cards') as e:
id_cards = load(e)
print '\nid_cards after change==',id_cards
答案 4 :(得分：1)
您可以通过两种方式完成，选择适合您需求的方式：
方法I。）使用行号替换。在这种情况下，您可以使用内置函数enumerate()：
首先，在读取模式中获取变量中的所有数据
with open("your_file.txt",'r') as f:
get_all=f.readlines()
其次，写入文件（枚举开始行动）
with open("your_file.txt",'w') as f:
for i,line in enumerate(get_all,1): ## STARTS THE NUMBERING FROM 1 (by default it begins with 0)
if i == 2: ## OVERWRITES line:2
f.writelines("Mage\n")
else:
f.writelines(line)
方法II。）使用您要替换的关键字：
以读取模式打开文件并将内容复制到列表
with open("some_file.txt","r") as f:
newline=[]
for word in f.readlines():
newline.append(word.replace("Warrior","Mage")) ## Replace the keyword while you copy.
“战士”已被“法师”取代，因此请将更新的数据写入文件：
with open("some_file.txt","w") as f:
for line in newline:
f.writelines(line)
输出就是这两种情况：
Dan Dan
Warrior ------> Mage
500 500
1 1
0 0
答案 5 :(得分：1)
我今晚一直在练习文件，并意识到我可以在Jochen的答案基础上为重复/多次使用提供更多功能。不幸的是，我的答案并没有解决处理大文件的问题，但确实在较小的文件中使生活更轻松。
with open('filetochange.txt', 'r+') as foo:
data = foo.readlines() #reads file as list
pos = int(input("Which position in list to edit? "))-1 #list position to edit
data.insert(pos, "more foo"+"\n") #inserts before item to edit
x = data[pos+1]
data.remove(x) #removes item to edit
foo.seek(0) #seeks beginning of file
for i in data:
i.strip() #strips "\n" from list items
foo.write(str(i))
答案 6 :(得分：0)
这是最简单的方法。
cout << "The value of num1 =" << num1 << " and the value of num2 " << num2 << ".";
我希望它对您有用。
答案 7 :(得分：0)
写入初始数据，打印一个空的str以将其更新为新数据
这里我们在代码的最后一行插入一个空的str，这个代码可以用于交互更新，换句话说就是在文本.txt文件中附加数据
with open("data.txt", 'w') as f:
f.write('first line\n'
'second line\n'
'third line\n'
'fourth line\n'
' \n')
更新文本文件最后一行的数据
my_file=open('data.txt')
string_list = my_file.readlines()
string_list[-1] = "Edit the list of strings as desired\n"
my_file = open("data.txt", "w")
new_file_contents = "". join(string_list)
my_file. write(new_file_contents)
答案 8 :(得分：-1)
1.06 => 1.1
1.03 => 1.1
1.02 => 1.0
答案 9 :(得分：-2)
假设我有一个名为file_name的文件，如下所示：
this is python
it is file handling
this is editing of line
我们必须将第2行替换为“修改完成”：
f=open("file_name","r+")
a=f.readlines()
for line in f:
if line.startswith("rai"):
p=a.index(line)
#so now we have the position of the line which to be modified
a[p]="modification is done"
f.seek(0)
f.truncate() #ersing all data from the file
f.close()
#so now we have an empty file and we will write the modified content now in the file
o=open("file_name","w")
for i in a:
o.write(i)
o.close()
#now the modification is done in the file