How would i store the variable x on a specific line (the first)in a text file and recover it as the program opens.
Also how would i store data in a text file on a specific line
You should take a look at the open() built-in.
#To write to a file:
with open("file.txt", "w") as f:
f.write("Data!")
#To read from a file:
with open("file.txt", "r") as f:
print(f.read())
Next time, you should check for duplicates:
easy save/load of data in python, Writing a Top Score to a data file.
Related
so i wrote a code to split a file(x) into multiple file(y), what if (y) already exist, how do i combine the new file with existing file
here are my current code:
with open('large.dat, encoding='utf-8') as infile, open ('small.dat', 'w', encoding='utf-8') as outfile:
for line in infile:
if '462888' in line:
outfile.write(line)
...
also i want to combine the content from new and existing file without having spaces between them
Open y in a or append mode, if it doesn't exist it will create it, if it does it will add data to it.
with open("y", "a") as file:
file.write("hello world\n")
I have to parse some data, I've successfully made a script that finds the start and end of the test, and will print out the data in between those.
Python, the line here is from the csv library
else:
print(line)
# csv_file = open(title+'.txt', "w")
# writer = csv.writer(csv_file)
# csv.writer(csv_file).writerow(line)
the csv writes extremely funky data instead of the line as a row. Printing out the line looks exactly as it does in the txt file.
Printing out the line looks exactly as it does in the txt file.
print function does accept optional file argument so if you want to write file exactly like it would look at stdout you might do
...
with open("file.txt","w") as f:
print(line, file=f)
I wrote the following python code snippet to append a lower p character to each line of a txt file:
f = open('helloworld.txt','r')
for line in f:
line+='p'
print(f.read())
f.close()
However, when I execute this python program, it returns nothing but an empty blank:
zhiwei#zhiwei-Lenovo-Rescuer-15ISK:~/Documents/1001/ass5$ python3 helloworld.py
Can anyone tell me what's wrong with my codes?
Currently, you are only reading each line and not writing to the file. reopen the file in write mode and write your full string to it, like so:
newf=""
with open('helloworld.txt','r') as f:
for line in f:
newf+=line.strip()+"p\n"
f.close()
with open('helloworld.txt','w') as f:
f.write(newf)
f.close()
well, type help(f) in shell, you can get "Character and line based layer over a BufferedIOBase object, buffer."
it's meaning：if you reading first buffer,you can get content, but again. it's empty。
so like this:
with open(oldfile, 'r') as f1, open(newfile, 'w') as f2:
newline = ''
for line in f1:
newline+=line.strip()+"p\n"
f2.write(newline)
open(filePath, openMode) takes two arguments, the first one is the path to your file, the second one is the mode it will be opened it. When you use 'r' as second argument, you are actually telling Python to open it as an only reading file.
If you want to write on it, you need to open it in writing mode, using 'w' as second argument. You can find more about how to read/write files in Python in its official documentation.
If you want to read and write at the same time, you have to open the file in both reading and writing modes. You can do this simply by using 'r+' mode.
It seems that your for loop has already read the file to the end, so f.read() return empty string.
If you just need to print the lines in the file, you could move the print into for loop just like print(line). And it is better to move the f.read() before for loop:
f = open("filename", "r")
lines = f.readlines()
for line in lines:
line += "p"
print(line)
f.close()
If you need to modify the file, you need to create another file obj and open it in mode of "w", and use f.write(line) to write the modified lines into the new file.
Besides, it is more better to use with clause in python instead of open(), it is more pythonic.
with open("filename", "r") as f:
lines = f.readlines()
for line in lines:
line += "p"
print(line)
When using with clause, you have no need to close file, this is more simple.
I have a text file which needs to be separated line by line into individual text files. So if the main file contains the strings:
foo
bar
bla
I would have 3 files which could be named numerically 1.txt (containing the string "foo"), 2.txt (sontaining the string"bar") and 3.txt (containing the string "bla")
The straightforward way to do with would be to open three files for writing and writing line by line into each file. But the problem is when we have lot of lines or we do not know exactly how many there are. It seems painfully unnecessary to have to create
f1=open('main_file', 'r')
f2=open('1.txt', 'w')
f3=open('2.txt', 'w')
f4=open('3.txt', 'w')
is there a way to put a counter in this operation or a library which can handle this type of ask?
Read the lines from the file in a loop, maintaining the line number; open a file with the name derived from the line number, and write the line into the file:
f1 = open('main_file', 'r')
for i,text in enumerate(f1):
open(str(i + 1) + '.txt', 'w').write(text)
You would want something like this. Using with is the preferred way for dealing with files, since it automatically closes them for you after the with scope.
with open('main_file', 'r') as in_file:
for line_number, line in enumerate(in_file):
with open("{}.txt".format(i+1), 'w') as out_file:
out_file.write(line)
Firstly you could read the file into a list, where each element stands for a row in the file.
with open('/path/to/data','r') as f:
data = [line.strip() for line in f]
Then you could use a for loop to write into files separately.
for counter in range(len(data)):
with open('/path/to/file/'+str(counter),'w') as f:
f.write(data[counter])
Notes:
Since you're continuously opening numerous files, I highly suggest using
with open() as f:
#your operation
The advantage of using this is that you can make sure Python release the resources on time.
Details:
What's the advantage of using 'with .. as' statement in Python?
I wrote a program that opens a file and read it line by line and store just the third element of each line. The problem is that, when I write those outputs into a file I need to change them as strings which is not suitable for me due to the fact that I want to do some mathematical operations on the written file later on. FYI, it also is not suitable to store it like this and use int() while reading it.
Can anybody help me with this issue?
with open("/home/test1_to_write", "w") as g:
with open("/home/test1_to_read", 'r') as f:
for line in f:
a=line.split()
number = int(a[3])
g.write(str(number)+'\n')
g.close()
There's no way to tell a text file that 1 is the number one not the letter "1". If you need that, consider storing the whole thing as a list instead using some sort of serial format e.g. JSON:
import json
with open("/home/test1_to_write.json", 'w') as outfile:
with open("/home/test1_to_read", 'r') as infile:
data = [int(line.split()[3]) for line in infile]
json.dump(data, outfile)
You can then load the data with:
with open("/home/test1_to_write.json", "r") as infile:
read_data = json.load(infile)