假设我有一个包含以下内容的文本文件：
Dan
Warrior
500
1
0
有没有一种方法可以编辑文本文件中的特定行？现在我有以下代码：
#!/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]是不正确的。但你懂我的意思，对吧？我想通过将第二行中的Warrior替换为Mage来进行编辑。但我能这样做吗？
# 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 )
with 语句块会更加简洁。 - Gabrieldef 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')
你可以使用 fileinput 来进行原地编辑
import fileinput
for line in fileinput.FileInput("myfile", inplace=1):
if line .....:
print line
有两种方法可以完成，选择适合您要求的：
方法 I.) 使用行号进行替换。在这种情况下，您可以使用内置函数 enumerate()：
首先，在读取模式 下将所有数据存储在一个变量中。
with open("your_file.txt",'r') as f:
get_all=f.readlines()
其次，写入文件（这是枚举发挥作用的地方）
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)
方法二.) 使用您想要替换的关键字:
以读模式打开文件，并将其内容复制到列表中。
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"已被替换为"法师"，因此请将更新后的数据写入文件：
with open("some_file.txt","w") as f:
for line in newline:
f.writelines(line)
这是两种情况下输出的结果:
Dan Dan
Warrior ------> Mage
500 500
1 1
0 0
如果您的文本只包含一个个体：
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()
# 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()
如果一个人的“工作”在文本中是固定长度的，那么您只需更改与所需个人对应的“工作”部分的文本即可：这与senderle的想法相同。
但是我认为更好的方法是将个人特征记录在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
今晚我一直在练习文件处理，发现可以在Jochen的答案基础上提供更多的重复/多次使用功能。不幸的是，我的答案没有解决处理大文件的问题，但确实可以使小文件的处理变得更加容易。
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))
我曾经有同样的需求，最终采用了Jinja模板。将您的文本文件更改为以下内容，并添加一个姓氏变量，然后通过传递lastname='Meg'来渲染模板，这是我能想到的最有效和最快速的方法。
Dan
{{ lastname }}
Warrior
500
1
0
file_name的文件，如下所示：this is python
it is file handling
this is editing of line
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
编写初始数据，打印一个空的str以便更新为新数据。
在代码的最后一行插入一个空的str，这段代码可以用于迭代更新，也就是将数据附加到文本.txt文件中。
with open("data.txt", 'w') as f:
f.write('first line\n'
'second line\n'
'third line\n'
'fourth line\n'
' \n')
更新文本文件中的最后一行数据
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)
#read file lines and edit specific item
file=open("pythonmydemo.txt",'r')
a=file.readlines()
print(a[0][6:11])
a[0]=a[0][0:5]+' Ericsson\n'
print(a[0])
file=open("pythonmydemo.txt",'w')
file.writelines(a)
file.close()
print(a)