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How do I search and replace text in a file using Python 3?
Here is my code:
import os
import sys
import fileinput
print ("Text to search for:")
textToSearch = input( "> " )
print ("Text to replace it with:")
textToReplace = input( "> " )
print ("File to perform Search-Replace on:")
fileToSearch = input( "> " )
#fileToSearch = 'D:\dummy1.txt'
tempFile = open( fileToSearch, 'r+' )
for line in fileinput.input( fileToSearch ):
if textToSearch in line :
print('Match Found')
else:
print('Match Not Found!!')
tempFile.write( line.replace( textToSearch, textToReplace ) )
tempFile.close()
input( '\n\n Press Enter to exit...' )
Input file:
hi this is abcd hi this is abcd
This is dummy text file.
This is how search and replace works abcd
When I search and replace 'ram' by 'abcd' in above input file, it works as a charm. But when I do it vice-versa i.e. replacing 'abcd' by 'ram', some junk characters are left at the end.
Replacing 'abcd' by 'ram'
hi this is ram hi this is ram
This is dummy text file.
This is how search and replace works rambcd
As pointed out by michaelb958, you cannot replace in place with data of a different length because this will put the rest of the sections out of place. I disagree with the other posters suggesting you read from one file and write to another. Instead, I would read the file into memory, fix the data up, and then write it out to the same file in a separate step.
# Read in the file
with open('file.txt', 'r') as file :
filedata = file.read()
# Replace the target string
filedata = filedata.replace('abcd', 'ram')
# Write the file out again
with open('file.txt', 'w') as file:
file.write(filedata)
Unless you've got a massive file to work with which is too big to load into memory in one go, or you are concerned about potential data loss if the process is interrupted during the second step in which you write data to the file.
fileinput already supports inplace editing. It redirects stdout to the file in this case:
#!/usr/bin/env python3
import fileinput
with fileinput.FileInput(filename, inplace=True, backup='.bak') as file:
for line in file:
print(line.replace(text_to_search, replacement_text), end='')
As Jack Aidley had posted and J.F. Sebastian pointed out, this code will not work:
# Read in the file
filedata = None
with file = open('file.txt', 'r') :
filedata = file.read()
# Replace the target string
filedata.replace('ram', 'abcd')
# Write the file out again
with file = open('file.txt', 'w') :
file.write(filedata)`
But this code WILL work (I've tested it):
f = open(filein,'r')
filedata = f.read()
f.close()
newdata = filedata.replace("old data","new data")
f = open(fileout,'w')
f.write(newdata)
f.close()
Using this method, filein and fileout can be the same file, because Python 3.3 will overwrite the file upon opening for write.
You can do the replacement like this
f1 = open('file1.txt', 'r')
f2 = open('file2.txt', 'w')
for line in f1:
f2.write(line.replace('old_text', 'new_text'))
f1.close()
f2.close()
You can also use pathlib.
from pathlib2 import Path
path = Path(file_to_search)
text = path.read_text()
text = text.replace(text_to_search, replacement_text)
path.write_text(text)
(pip install python-util)
from pyutil import filereplace
filereplace("somefile.txt","abcd","ram")
Will replace all occurences of "abcd" with "ram".
The function also supports regex by specifying regex=True
from pyutil import filereplace
filereplace("somefile.txt","\\w+","ram",regex=True)
Disclaimer: I'm the author (https://github.com/MisterL2/python-util)
Open the file in read mode. Read the file in string format. Replace the text as intended. Close the file. Again open the file in write mode. Finally, write the replaced text to the same file.
try:
with open("file_name", "r+") as text_file:
texts = text_file.read()
texts = texts.replace("to_replace", "replace_string")
with open(file_name, "w") as text_file:
text_file.write(texts)
except FileNotFoundError as f:
print("Could not find the file you are trying to read.")
Late answer, but this is what I use to find and replace inside a text file:
with open("test.txt") as r:
text = r.read().replace("THIS", "THAT")
with open("test.txt", "w") as w:
w.write(text)
DEMO
With a single with block, you can search and replace your text:
with open('file.txt','r+') as f:
filedata = f.read()
filedata = filedata.replace('abc','xyz')
f.truncate(0)
f.write(filedata)
Your problem stems from reading from and writing to the same file. Rather than opening fileToSearch for writing, open an actual temporary file and then after you're done and have closed tempFile, use os.rename to move the new file over fileToSearch.
My variant, one word at a time on the entire file.
I read it into memory.
def replace_word(infile,old_word,new_word):
if not os.path.isfile(infile):
print ("Error on replace_word, not a regular file: "+infile)
sys.exit(1)
f1=open(infile,'r').read()
f2=open(infile,'w')
m=f1.replace(old_word,new_word)
f2.write(m)
Using re.subn it is possible to have more control on the substitution process, such as word splitted over two lines, case-(in)sensitive match. Further, it returns the amount of matches which can be used to avoid waste of resources if the string is not found.
import re
file = # path to file
# they can be also raw string and regex
textToSearch = r'Ha.*O' # here an example with a regex
textToReplace = 'hallo'
# read and replace
with open(file, 'r') as fd:
# sample case-insensitive find-and-replace
text, counter = re.subn(textToSearch, textToReplace, fd.read(), re.I)
# check if there is at least a match
if counter > 0:
# edit the file
with open(file, 'w') as fd:
fd.write(text)
# summary result
print(f'{counter} occurence of "{textToSearch}" were replaced with "{textToReplace}".')
Some regex:
add the re.I flag, short form of re.IGNORECASE, for a case-insensitive match
for multi-line replacement re.subn(r'\n*'.join(textToSearch), textToReplace, fd.read()), depending on the data also '\n{,1}'. Notice that for this case textToSearch must be a pure string, not a regex!
Besides the answers already mentioned, here is an explanation of why you have some random characters at the end:
You are opening the file in r+ mode, not w mode. The key difference is that w mode clears the contents of the file as soon as you open it, whereas r+ doesn't.
This means that if your file content is "123456789" and you write "www" to it, you get "www456789". It overwrites the characters with the new input, but leaves any remaining input untouched.
You can clear a section of the file contents by using truncate(<startPosition>), but you are probably best off saving the updated file content to a string first, then doing truncate(0) and writing it all at once.
Or you can use my library :D
I got the same issue. The problem is that when you load a .txt in a variable you use it like an array of string while it's an array of character.
swapString = []
with open(filepath) as f:
s = f.read()
for each in s:
swapString.append(str(each).replace('this','that'))
s = swapString
print(s)
I tried this and used readlines instead of read
with open('dummy.txt','r') as file:
list = file.readlines()
print(f'before removal {list}')
for i in list[:]:
list.remove(i)
print(f'After removal {list}')
with open('dummy.txt','w+') as f:
for i in list:
f.write(i)
you can use sed or awk or grep in python (with some restrictions). Here is a very simple example. It changes banana to bananatoothpaste in the file. You can edit and use it. ( I tested it worked...note: if you are testing under windows you should install "sed" command and set the path first)
import os
file="a.txt"
oldtext="Banana"
newtext=" BananaToothpaste"
os.system('sed -i "s/{}/{}/g" {}'.format(oldtext,newtext,file))
#print(f'sed -i "s/{oldtext}/{newtext}/g" {file}')
print('This command was applied: sed -i "s/{}/{}/g" {}'.format(oldtext,newtext,file))
if you want to see results on the file directly apply: "type" for windows/ "cat" for linux:
####FOR WINDOWS:
os.popen("type " + file).read()
####FOR LINUX:
os.popen("cat " + file).read()
I have done this:
#!/usr/bin/env python3
import fileinput
import os
Dir = input ("Source directory: ")
os.chdir(Dir)
Filelist = os.listdir()
print('File list: ',Filelist)
NomeFile = input ("Insert file name: ")
CarOr = input ("Text to search: ")
CarNew = input ("New text: ")
with fileinput.FileInput(NomeFile, inplace=True, backup='.bak') as file:
for line in file:
print(line.replace(CarOr, CarNew), end='')
file.close ()
I modified Jayram Singh's post slightly in order to replace every instance of a '!' character to a number which I wanted to increment with each instance. Thought it might be helpful to someone who wanted to modify a character that occurred more than once per line and wanted to iterate. Hope that helps someone. PS- I'm very new at coding so apologies if my post is inappropriate in any way, but this worked for me.
f1 = open('file1.txt', 'r')
f2 = open('file2.txt', 'w')
n = 1
# if word=='!'replace w/ [n] & increment n; else append same word to
# file2
for line in f1:
for word in line:
if word == '!':
f2.write(word.replace('!', f'[{n}]'))
n += 1
else:
f2.write(word)
f1.close()
f2.close()
def word_replace(filename,old,new):
c=0
with open(filename,'r+',encoding ='utf-8') as f:
a=f.read()
b=a.split()
for i in range(0,len(b)):
if b[i]==old:
c=c+1
old=old.center(len(old)+2)
new=new.center(len(new)+2)
d=a.replace(old,new,c)
f.truncate(0)
f.seek(0)
f.write(d)
print('All words have been replaced!!!')
I have worked this out as an exercise of a course: open file, find and replace string and write to a new file.
class Letter:
def __init__(self):
with open("./Input/Names/invited_names.txt", "r") as file:
# read the list of names
list_names = [line.rstrip() for line in file]
with open("./Input/Letters/starting_letter.docx", "r") as f:
# read letter
file_source = f.read()
for name in list_names:
with open(f"./Output/ReadyToSend/LetterTo{name}.docx", "w") as f:
# replace [name] with name of the list in the file
replace_string = file_source.replace('[name]', name)
# write to a new file
f.write(replace_string)
brief = Letter()
Like so:
def find_and_replace(file, word, replacement):
with open(file, 'r+') as f:
text = f.read()
f.write(text.replace(word, replacement))
def findReplace(find, replace):
import os
src = os.path.join(os.getcwd(), os.pardir)
for path, dirs, files in os.walk(os.path.abspath(src)):
for name in files:
if name.endswith('.py'):
filepath = os.path.join(path, name)
with open(filepath) as f:
s = f.read()
s = s.replace(find, replace)
with open(filepath, "w") as f:
f.write(s)
I'm making a program that takes text from an input file, then you input a file where it copies the already existing file text. Then, I need to replace a few words there and print the count of how many of these words were replaced. This is my code so far, but since with loops close the newly created file, I have no idea how to open it back again for reading and writing and counting. This is my awful code so far:
filename=input("Sisesta tekstifaili nimi: ")
inputFile=open(filename, "r")
b=input("Sisesta uue tekstifaili nimi: ")
uusFail=open(b+".txt", "w+")
f=uusFail
with inputFile as input:
with uusFail as output:
for line in input:
output.write(line)
lines[]
asendus = {'hello':'tere', 'Hello':'Tere'}
with uusFail as infile
for line in infile
for src, target in asendus
line = line, replace(src, target)
lines.append(line)
with uusFail as outfile:
for line in lines:
outfile.write(line)
There are a lot of unnecessary loops in your code. when you read the file, you can treat it as a whole and count the number of occurrences and replace them. Here is a modified version of your code:
infile = input('Enter file name: ')
outfile = input('enter out file: ')
with open(infile) as f:
content = f.read()
asendus = {'hello':'tere', 'Hello':'Tere'}
my_count = 0
for src, target in asendus.items():
my_count += content.count(src)
content = content.replace(src, target)
with open(f'{outfile}.txt','w+' ) as f:
f.write(content)
You need to reopen the file in the second block of code:
with open(b+".txt", "r") as infile:
I'm a bit new to Python and I am trying to simplify my existing code.
Right now, I have the code repeated 5 times with different strings. I'd like to have the code one time and have it run through a list of strings.
Currently what I have:
def wiScanFormat():
File = open("/home/pi/gpsMaster/WiScan.txt", "r")
data = File.read()
File.close()
MAC = data.replace("Address:", "\nAddress, ")
File = open("/home/pi/gpsMaster/WiScan.txt", "w")
File.write(MAC)
File.close()
File = open("/home/pi/gpsMaster/WiScan.txt", "r")
data = File.read()
File.close()
SSID = data.replace("ESSID:", "\nESSID, ")
File = open("/home/pi/gpsMaster/WiScan.txt", "w")
File.write(SSID)
File.close()
File = open("/home/pi/gpsMaster/WiScan.txt", "r")
data = File.read()
File.close()
FREQ = data.replace("Frequency:", "\nFrequency, ")
File = open("/home/pi/gpsMaster/WiScan.txt", "w")
File.write(FREQ)
File.close()
File = open("/home/pi/gpsMaster/WiScan.txt", "r")
data = File.read()
File.close()
QUAL = data.replace("Quality", "\nQuality, ")
File = open("/home/pi/gpsMaster/WiScan.txt", "w")
File.write(QUAL)
File.close()
File = open("/home/pi/gpsMaster/WiScan.txt", "r")
data = File.read()
File.close()
SIG = data.replace("Signal level", "\nSignal Level, ")
File = open("/home/pi/gpsMaster/WiScan.txt", "w")
File.write(SIG)
File.close()
What I'd like to have:
ORG = ['Address:', 'ESSID:'...etc]
NEW = ['\nAddress, ' , '\nESSID, ' , ... etc]
and run that through:
File = open("/home/pi/gpsMaster/WiScan.txt", "r")
data = File.read()
File.close()
ID = data.replace("ORG", "NEW")
File = open("/home/pi/gpsMaster/WiScan.txt", "w")
File.write(ID)
File.close()
I've tried running exactly what I put up, but it does not seem to format it the way I need to.
The output from above looks like:
Cell 46 - Address: xx:xx:xx:xx:xx:xx ESSID:"MySSID" Frequency:2.412 GHz (Channel 1) Quality=47/100 Signal level=48/100 Quality=47/100 Signal level=48/100
But it is supposed to look like this (And it does when I run that same block over the strings separately):
xx:xx:xx:xx:xx:xx MySSID 5.18 GHz (Channel 36) 0.81 0.99
How should I go about looping this block of code through my list of strings?
There two strings that I would need for the find and replace, old and new, so they would have to work together. These lists will be the same size, obviously, and I need them to be in the correct order. Address with address, ESSID with ESSID, etc.
Thanks in advance!
Try something like this:
ORG = ['Address:', 'ESSID:'...etc]
NEW = ['\nAddress, ' , '\nESSID, ' , ... etc]
File = open("/home/pi/gpsMaster/WiScan.txt", "r")
data = File.read()
File.close()
for org, new in zip(ORG, NEW):
data = data.replace(org, new)
File = open("/home/pi/gpsMaster/WiScan.txt", "w")
File.write(data)
File.close()
(Note the way zip works: https://docs.python.org/2/library/functions.html#zip)
If I am reading your question right, you are opening the same file, making a small alteration, saving it, and then closing it again, five times. You could just open it once, make all the alterations, and then save it. For instance, like this:
filename = "/home/pi/gpsMaster/WiScan.txt"
with open(filename, 'r') as fin:
data = fin.read()
data = data.replace("Address:", "\nAddress, ")
data = data.replace("ESSID:", "\nESSID, ")
data = data.replace("Frequency:", "\nFrequency, ")
data = data.replace("Quality", "\nQuality, ")
data = data.replace("Signal level", "\nSignal Level, ")
with open(filename, 'w') as fout:
fout.write(data)
If you want to use lists (ORG and NEW) for your replacements, you could do this:
with open(filename, 'r') as fin:
data = fin.read()
for o,n in zip(ORG, NEW):
data = data.replace(o,n)
with open(filename, 'w') as fout:
fout.write(data)
Given your ORG and NEW, the simplest way to do this would be something like:
# Open once for both read and write; use with statement for guaranteed close at end of block
with open("/home/pi/gpsMaster/WiScan.txt", "r+") as f:
data = f.read() # Slurp file
f.seek(0) # Seek back to beginning of file
# Perform all replacements
for orig, repl in zip(ORG, NEW):
data = data.replace(orig, repl)
f.write(data) # Write new data over old
f.truncate() # If replacement shrunk file, truncate extra
You could just do this:
def wiScanFormat(path = "/home/pi/gpsMaster/WiScan.txt"):
# List of tuples with strings to find and strings to replace with
replacestr = [
("Address:", "\nAddress, "),
("ESSID:", "\nESSID, "),
("Frequency:", "\nFrequency, "),
("Quality", "\nQuality, "),
("Signal level", "\nSignal Level, ")
]
with open(path, "r") as file: # Open a file
data = file.read()
formated = data
for i in replacestr: # Loop over each element (tuple) in the list
formated = formated.replace(i[0], i[1]) # Replace the data
with open(path, "w") as file:
written = file.write(formated) # Write the data
return written
I am trying to append values to a json file. How can i append the data? I have been trying so many ways but none are working ?
Code:
def all(title,author,body,type):
title = "hello"
author = "njas"
body = "vgbhn"
data = {
"id" : id,
"author": author,
"body" : body,
"title" : title,
"type" : type
}
data_json = json.dumps(data)
#data = ast.literal_eval(data)
#print data_json
if(os.path.isfile("offline_post.json")):
with open('offline_post.json','a') as f:
new = json.loads(f)
new.update(a_dict)
json.dump(new,f)
else:
open('offline_post.json', 'a')
with open('offline_post.json','a') as f:
new = json.loads(f)
new.update(a_dict)
json.dump(new,f)
How can I append data to json file when this function is called?
I suspect you left out that you're getting a TypeError in the blocks where you're trying to write the file. Here's where you're trying to write:
with open('offline_post.json','a') as f:
new = json.loads(f)
new.update(a_dict)
json.dump(new,f)
There's a couple of problems here. First, you're passing a file object to the json.loads command, which expects a string. You probably meant to use json.load.
Second, you're opening the file in append mode, which places the pointer at the end of the file. When you run the json.load, you're not going to get anything because it's reading at the end of the file. You would need to seek to 0 before loading (edit: this would fail anyway, as append mode is not readable).
Third, when you json.dump the new data to the file, it's going to append it to the file in addition to the old data. From the structure, it appears you want to replace the contents of the file (as the new data contains the old data already).
You probably want to use r+ mode, seeking back to the start of the file between the read and write, and truncateing at the end just in case the size of the data structure ever shrinks.
with open('offline_post.json', 'r+') as f:
new = json.load(f)
new.update(a_dict)
f.seek(0)
json.dump(new, f)
f.truncate()
Alternatively, you can open the file twice:
with open('offline_post.json', 'r') as f:
new = json.load(f)
new.update(a_dict)
with open('offline_post.json', 'w') as f:
json.dump(new, f)
This is a different approach, I just wanted to append without reloading all the data. Running on a raspberry pi so want to look after memory. The test code -
import os
json_file_exists = 0
filename = "/home/pi/scratch_pad/test.json"
# remove the last run json data
try:
os.remove(filename)
except OSError:
pass
count = 0
boiler = 90
tower = 78
while count<10:
if json_file_exists==0:
# create the json file
with open(filename, mode = 'w') as fw:
json_string = "[\n\t{'boiler':"+str(boiler)+",'tower':"+str(tower)+"}\n]"
fw.write(json_string)
json_file_exists=1
else:
# append to the json file
char = ""
boiler = boiler + .01
tower = tower + .02
while(char<>"}"):
with open(filename, mode = 'rb+') as f:
f.seek(-1,2)
size=f.tell()
char = f.read()
if char == "}":
break
f.truncate(size-1)
with open(filename, mode = 'a') as fw:
json_string = "\n\t,{'boiler':"+str(boiler)+",'tower':"+str(tower)+"}\n]"
fw.seek(-1, os.SEEK_END)
fw.write(json_string)
count = count + 1
I've seen really complex answers on this website as how to edit a specific line on a file but I was wondering if there was a simple way to do it?
I want to search for a name in a file, and on the line that I find that name on, I want to add an integer to the end of the line (as it is a score for a quiz). Or could you tell me how I can replace the entirety of the line with new data?
I have tried a lot of coding but either no change is made, or all of the data in the file gets deleted.
I tried this....
with open ('File.py', 'r') as class_file:
for number, line in enumerate(class_file):
if name in line:
s=open('File.py', 'r').readlines()
s[number]=str(data)
class_file=open('File.py', 'w')
class_file.writelines(new_score)
class_file.close()
As well as this function....
def replace (file, line_number, add_score):
s=open(file, 'w')
new_data=line[line_number].replace(line, add_score)
s.write(str(new_data))
s.close()
As well as this...
def replace_score(file_name, line_num, text):
new = open(file_name, 'r').readlines()
new[line_num] = text
adding_score= open(file_name, 'w')
adding_score.writelines(new)
adding_score.close()
But I still can't get it to work.
The last code works if I'm trying to replace the first line, but not the others.
You need to get the content of the file. Close the file. Modify the content and rewrite the file with the modified content. Try the following:
def replace_score(file_name, line_num, text):
f = open(file_name, 'r')
contents = f.readlines()
f.close()
contents[line_num] = text+"\n"
f = open(file_name, "w")
contents = "".join(contents)
f.write(contents)
f.close()
replace_score("file_path", 10, "replacing_text")
This is Tim Osadchiy's code:
def replace_score(file_name, line_num, text):
f = open(file_name, 'r')
contents = f.readlines()
f.close()
contents[line_num] = text+"\n"
f = open(file_name, "w")
contents = "".join(contents)
f.write(contents)
f.close()
replace_score("file_path", 10, "replacing_text")
This code does work but just remember that the line_num will always be one above the actual line number (as it is an index). So if you wanted line 9 then enter 8, not 9. Also, do not forget to put .txt at the end of the file path (I would've commented but do not have a high enough reputation)