I'm trying to replace each "zzz" with a number. There is no output at execution and the file content remains the same. Here's what I have:
n = 0
file = open("filename", "a")
for line in file:
if "zzz" in line:
line.replace("zzz", n, 1)
n += 1
There are a few issues here. First, the replace method doesn't alter the string in place but rather creates a new string. Therefore, if you don't assign the new value to something, you're going to lose it.
Second, you're trying to read from the file but you're opening it in append mode. You need to open it with "r" instead of "a".
Third, you can't pass an integer (n) as the second argument to replace. You need to convert it to a string.
Finally, you're not writing the contents back to the file. That's why it's unchanged. I recommend reading all of the data in, altering it, and then re-opening the file in write mode.
n = 0
with open("filename", "r") as f:
lines = f.readlines()
for k, line in enumerate(lines):
if "zzz" in line:
lines[k] = line.replace("zzz", str(n), 1)
n += 1
with open("filename", "w") as f:
f.write("".join(lines))
Related
The text file is "ics2o.txt" and I don't know how to print numbers next to the lines
import random
print ("----------------------------------------------------------")
print ("Student Name Student Mark")
print ("----------------------------------------------------------")
f = open("ics2o.txt")
for line in f:
x = len(f.readlines())
for i in range (x):
contents = f.read()
print(str(contents) + str(random.randint(75,100)))
for line in f:
x = len(f.readlines())
for i in range (x):
contents = f.read()
print(str(contents) + str(random.randint(75,100)))
The problem is that you are reading the file in at least 3 different ways which causes none of them to work the way you want. In particular, f.readlines() consumes the entire file buffer, so when you next do f.read() there is nothing left to read. Don't mix and match these. Instead, you should use line since you are iterating over the file already:
for line in f:
print(line + str(random.randint(75,100)))
The lesson here is don't make things any more complicated than they need to be.
Firstly, doing print("----...") is a bad practice, at least use string multiplication:print("-"*10)
Secondly, always open files using 'with' keyword. (u can google it up why)
Thirdly, the code:
with open("ics2o.txt") as f:
for i,j in enumerate(f):
print(i,j)
I want to be able to open the file i have, and append it so that if i want to subtract the number in the file by 2, it would print out the answer in the console by opening the file and reading it.
e.g. if the number in the file was 156, i would have to subtract it by 2, which is 154, this will then be displayed on the console!
this is all i have so far:
a = file.open("xp.txt", "r")
a.read()
a.close()
How would i update it so that if i wanted to subtract it by an integer, that integer would be displayed on console?
Thanks in advance!
Use readline instead of read so that you won't get an error when the file for example contains another empty line. Then, call strip on the result to eliminate possible whitespace. Finally, use int to convert the string to a number. Now you can do all the math you want with it:
with open("xp.txt", "r") as infile:
value = infile.readline()
stripped = value.strip()
number = int(stripped)
newNumber = number - 2
print(newNumber)
Or shorter:
with open("xp.txt", "r") as infile:
print(int(infile.readline().strip()) - 2)
To write the number to the same file, convert the number back to a string:
with open("xp.txt", "r") as infile:
result = int(infile.readline().strip()) - 2
print(result)
with open("xp.txt" , "w") as outfile:
outfile.write(str(result))
Assuming the file just contained that single value and nothing else, you could accomplish this using the following
with open('xp.txt', 'r') as f_in:
value = int(a.read())
value -= 2
print(f'New value is {value}')
with open('xp.txt', 'w') as f_out:
f_out.write(str(value))
Basically you open the file for reading, read the value into an integer, modify the value and display it, then re-open the file for writing to write the value back out.
I am currently keeping high scores into a text file called "score.txt". The prgoram works fine, updating the file with the new high scores as normal. Except that every time the program updates the file, there is always one blank line before the first high score, creating an error when I try to save the scores the next time. The code:
scores_list = []
score = 10
def take_score():
# Save old scores into list
f = open("score.txt", "r")
lines = f.readlines()
for line in lines:
scores_list.append(line)
print scores_list
f.close()
take_score()
def save_score():
# Clear file
f = open("score.txt", "w")
print >> f, ""
f.close()
# Rewrite scores into text files
w = open("score.txt", "a")
for i in range(0, len(scores_list)):
new_string = scores_list[i].replace("\n", "")
scores_list[i] = int(new_string)
if score > scores_list[i]:
scores_list[i] = score
for p in range(0, len(scores_list)):
print >> w, str(scores_list[p])
print repr(str(scores_list[p]))
save_score()
The problem mentioned happens in the save_score() function. I have tried this related question: Removing spaces and empty lines from a file Using Python, but it requires I open the file in "r" mode. Is there a way to accomplish the same thing except when the file is opened in "a" mode (append)?
You are specifically printing an empty line as soon as you create the file.
print >> f, ""
You then append to it, keeping the empty line.
If you just want to clear the contents every time you run this, get rid of this:
# Clear file
f = open("score.txt", "w")
print >> f, ""
f.close()
And modify the opening to this:
w = open("score.txt", "w")
The 'w' mode truncates already, as you were already using. There's no need to truncate, write an empty line, close, then append lines. Just truncate and write what you want to write.
That said, you should use the with construct and file methods for working with files:
with open("score.txt", "w") as output: # here's the with construct
for i in xrange(len(scores_list)):
# int() can handle leading/trailing whitespace
scores_list[i] = int(scores_list[i])
if score > scores_list[i]:
scores_list[i] = score
for p in xrange(len(scores_list)):
output.write(str(scores_list[p]) + '\n') # writing to the file
print repr(str(scores_list[p]))
You will then not need to explicitly close() the file handle, as with takes care of that automatically and more reliably. Also note that you can simply send a single argument to range and it will iterate from 0, inclusive, until that argument, exclusive, so I've removed the redundant starting argument, 0. I've also changed range to the more efficient xrange, as range would only be reasonably useful here if you wanted compatibility with Python 3, and you're using Python 2-style print statements anyway, so there isn't much point.
print appends a newline to what you print. In the line
print >> f, ""
You're writing a newline to the file. This newline still exists when you reopen in append mode.
As #Zizouz212 mentions, you don't need to do all this. Just open in write mode, which'll truncate the file, then write what you need.
Your opening a file, clearing it, but then you open the same file again unnecessarily. When you open the file, you print a newline, even if you don't think so. Here is the offending line:
print >> f, ""
In Python 2, it really does this.
print "" + "\n"
This is because Python adds a newline at the end of the string to each print statement. To stop this, you could add a comma to the end of the statement:
print "",
Or just write directly:
f.write("my data")
However, if you're trying to save a Python data type, and it does not have to be human-readable, you may have luck using pickle. It's really simple to use:
def save_score():
with open('scores.txt', 'w') as f:
pickle.dump(score_data, f):
It is not really answer for question.
It is my version of your code (not tested). And don't avoid rewriting everything ;)
# --- functions ---
def take_score():
'''read values and convert to int'''
scores = []
with open("score.txt", "r") as f
for line in f:
value = int(line.strip())
scores.append(value)
return scores
def save_score(scores):
'''save values'''
with open("score.txt", "w") as f
for value in scores:
write(value)
write("\n")
def check_scores(scores, min_value):
results = []
for value in scores:
if value < min_value:
value = min_value
results.append(value)
return resulst
# --- main ---
score = 10
scores_list = take_score()
scores_list = check_scores(scores_list, score)
save_score(scores_list)
I have a file like this below.
0 0 0
0.00254 0.00047 0.00089
0.54230 0.87300 0.74500
0 0 0
I want to modify this file. If a value is less than 0.05, then a value is to be 1. Otherwise, a value is to be 0.
After python script runs, the file should be like
1 1 1
1 1 1
0 0 0
1 1 1
Would you please help me?
OK, since you're new to StackOverflow (welcome!) I'll walk you through this. I'm assuming your file is called test.txt.
with open("test.txt") as infile, open("new.txt", "w") as outfile:
opens the files we need, our input file and a new output file. The with statement ensures that the files will be closed after the block is exited.
for line in infile:
loops through the file line by line.
values = [float(value) for value in line.split()]
Now this is more complicated. Every line contains space-separated values. These can be split into a list of strings using line.split(). But they are still strings, so they must be converted to floats first. All this is done with a list comprehension. The result is that, for example, after the second line has been processed this way, values is now the following list: [0.00254, 0.00047, 0.00089].
results = ["1" if value < 0.05 else "0" for value in values]
Now we're creating a new list called results. Each element corresponds to an element of values, and it's going to be a "1" if that value < 0.05, or a "0" if it isn't.
outfile.write(" ".join(results))
converts the list of "integer strings" back to a string, separated by 7 spaces each.
outfile.write("\n")
adds a newline. Done.
The two list comprehensions could be combined into one, if you don't mind the extra complexity:
results = ["1" if float(value) < 0.05 else "0" for value in line.split()]
if you can use libraries I'd suggest numpy :
import numpy as np
myarray = np.genfromtxt("my_path_to_text_file.txt")
my_shape = myarray.shape()
out_array = np.where(my_array < 0.05, 1, 0)
np.savetxt(out_array)
You can add formating as arguments to the savetxt function. The docstrings of the function are pretty self explanatory.
If you are stuck with pure python :
with open("my_path_to_text_file") as my_file:
list_of_lines = my_file.readlines()
list_of_lines = [[int( float(x) < 0.05) for x in line.split()] for line in list_of_lines]
then write that list to file as you see fit.
You can use this code
f_in=open("file_in.txt", "r") #opens a file in the reading mode
in_lines=f_in.readlines() #reads it line by line
out=[]
for line in in_lines:
list_values=line.split() #separate elements by the spaces, returning a list with the numbers as strings
for i in range(len(list_values)):
list_values[i]=eval(list_values[i]) #converts them to floats
# print list_values[i],
if list_values[i]<0.05: #your condition
# print ">>", 1
list_values[i]=1
else:
# print ">>", 0
list_values[i]=0
out.append(list_values) #stores the numbers in a list, where each list corresponds to a lines' content
f_in.close() #closes the file
f_out=open("file_out.txt", "w") #opens a new file in the writing mode
for cur_list in out:
for i in cur_list:
f_out.write(str(i)+"\t") #writes each number, plus a tab
f_out.write("\n") #writes a newline
f_out.close() #closes the file
The following code performs the replacements in-place: for that , the file is opened in 'rb+' mode. It's absolutely mandatory to open it in binary mode b. The + in 'rb+' means that it's possible to write and to read in the file. Note that the mode can be written 'r+b' also.
But using 'rb+' is awkward:
if you read with for line in f , the file is read by chunks and several lines are kept in the buffer where they are really read one after the other, until another chunk of data is read and loaded in the buffer. That makes it harder to perform transformations, because one must follow the position of the file's pointer with the help of tell() and to move the pointer with seek() and in fact I've not completly understood how it must done.
.
Happily, there's a solution with replace(), because , I don't know why, but I believe the facts, when readline() reads a line, the file 's pointer doesn't go further on disk than the end of the line (that is to say it stops at the newline).
Now it's easy to move and know positions of the file's pointer
to make writing after reading, it's necessary to make seek() being executed , even if it should be to do seek(0,1), meaning a move of 0 caracters from the actual position. That must change the state of the file's pointer, something like that.
Well, for your problem, the code is as follows:
import re
from os import fsync
from os.path import getsize
reg = re.compile('[\d.]+')
def ripl(m):
g = m.group()
return ('1' if float(g)<0.5 else '0').ljust(len(g))
path = ...........'
print 'length of file before : %d' % getsize(path)
with open('Copie de tixti.txt','rb+') as f:
line = 'go'
while line:
line = f.readline()
lg = len(line)
f.seek(-lg,1)
f.write(reg.sub(ripl,line))
f.flush()
fsync(f.fileno())
print 'length of file after : %d' % getsize(path)
flush() and fsync() must be executed to ensure that the instruction f.write(reg.sub(ripl,line)) effectively writes at the moment it is ordred to.
Note that I've never managed a file encoded in unicode like. It's certainly still more dificult since every unicode character is encoded on several bytes (and in the case of UTF8 , variable number of bytes depending on the character)
I am writing a python script in order to write a tex file. But I had to use some information from another file. Such file has names of menus in each line that I need to use. I use split to have a list for each line of my "menu".
For example, I had to write a section with the each second element of my lists but after running, I got anything, what could I do?
This is roughly what I am doing:
texfile = open(outputtex.tex', 'w')
infile = open(txtfile.txt, 'r')
for line in infile.readlines():
linesplit = line.split('^')
for i in range(1,len(infile.readlines())):
texfile.write('\section{}\n'.format(linesplit[1]))
texfile.write('\\begin{figure*}[h!]\n')
texfile.write('\centering\n')
texfile.write('\includegraphics[scale=0.95]{pg_000%i.pdf}\n' %i)
texfile.write('\end{figure*}\n')
texfile.write('\\newpage\n')
texfile.write('\end{document}')
texfile.close()
By the way, in the inclugraphics line, I had to increace the number after pg_ from "0001" to "25050". Any clues??
I really appreciate your help.
I don't quite follow your question. But I see several errors in your code. Most importantly:
for line in infile.readlines():
...
...
for i in range(1,len(infile.readlines())):
Once you read a file, it's gone. (You can get it back, but in this case there's no point.) That means that the second call to readlines is yielding nothing, so len(infile.readlines()) == 0. Assuming what you've written here really is what you want to do (i.e. write file_len * (file_len - 1) + 1 lines?) then perhaps you should save the file to a list. Also, you didn't put quotes around your filenames, and your indentation is strange. Try this:
with open('txtfile.txt', 'r') as infile: # (with automatically closes infile)
in_lines = infile.readlines()
in_len = len(in_lines)
texfile = open('outputtex.tex', 'w')
for line in in_lines:
linesplit = line.split('^')
for i in range(1, in_len):
texfile.write('\section{}\n'.format(linesplit[1]))
texfile.write('\\begin{figure*}[h!]\n')
texfile.write('\centering\n')
texfile.write('\includegraphics[scale=0.95]{pg_000%i.pdf}\n' %i)
texfile.write('\end{figure*}\n')
texfile.write('\\newpage\n')
texfile.write('\end{document}')
texfile.close()
Perhaps you don't actually want nested loops?
infile = open('txtfile.txt', 'r')
texfile = open('outputtex.tex', 'w')
for line_number, line in enumerate(infile):
linesplit = line.split('^')
texfile.write('\section{{{0}}}\n'.format(linesplit[1]))
texfile.write('\\begin{figure*}[h!]\n')
texfile.write('\centering\n')
texfile.write('\includegraphics[scale=0.95]{pg_000%i.pdf}\n' % line_number)
texfile.write('\end{figure*}\n')
texfile.write('\\newpage\n')
texfile.write('\end{document}')
texfile.close()
infile.close()