I understand this is possible,
for r in range(0,1000):
print(("l1" + str(r)), end="\r")
time.sleep(0.1)
where this would print on the same line. Is it possible to do something like "\r\r" which will print one line above as well?
It is not possible to print anything on the line above in Python. Since newlines are simply \n, a string like:
Hello
World
Ends up looking like:
Hello\nWorld
Multiple print statements only add to this stream of characters, which makes it impossible to add anything before what has already been written, or in your case, the line above.
Related
I want to ovewrite 2 separate print lines in while True loop. I tried \r and \n but it is not working. When using \r \n override only 1 line or 2 line prints continously.how i fix this?
import sys
import time
tot = 5
new = 2
while True:
sys.stdout.write('{0}\n\r'.format(tot))
sys.stdout.write('{0}\n\r'.format(new))
sys.stdout.flush()
time.sleep(1)
tot += 1
new += 1
\r brings you to the beginning of the line where you will start overwriting stuff.
\n adds a newline
\n\r takes you to the next line, and then bring you to the beginning of that line, which is already a blank new line, and so the \r isn't actually doing anything and this is the same as just doing \n.
If you only wish to overwrite a single line you can do this with \r followed by your text. Make sure that whatever you print out has enough spaces at the end of it to make it the same length as the line you are overwriting, otherwise, you'll end up with part of the line not getting overwritten.
But since you've clarified that you need to overwrite multiple lines, things are a little bit trickier. Carriage returns (\r) were originally created to help with problems early printers had (This Wikipedia article explains these problems). There is a completely different mechanism for overwriting multiple lines that isn't exposed natively by Python, but this Stack Overflow question lists a few 3rd party libraries you can install that will help you accomplish this.
To overwrite the previous line, you need to have not yet output a newline. So I don't think you can overwrite multiple lines, sadly. To do one though, try something like this:
while some_condition:
sys.stdout.write("\r{0}".format("your text here"))
sys.stdout.flush()
The \r here (called a "carriage return") moves the printing cursor back to the beginning of the line (ie, to right after the most recent newline \n). You cannot go back farther than that, though.
For example, let's say one of the printed things is "Hello World" and the second is "Hello". How would I print "Hello" on the same line as the one that says "Hello World"? This is just an example. Realistically I have no idea how long the printed text will be.
Here is an example script:
x = open("file.txt", "r+").read().split("\n")
for i in x:
print(something)
where something = I don't know. I want the output to be what the first line of the text file says, then what the second line says, and so on except print the second/third/fourth... line over the first line and each line is an unknown length, some shorter than others. Lets say the file.txt says:
Overflow
Stack
I would want it to print "Overflow" then "Stack", except each word gets printed on the first line and once you print "Stack", every part of "Overflow" can't be seen
Keep in mind that print("Hello World", end="\r") won't work because of the length.
You could work around the \r solution by padding each line with spaces according to the previous line:
prev_size = 0
with open("file.txt", "r+") as f:
for line in f:
print(f"{line.strip()}{' '*prev_size}", end='\r')
prev_size = len(line)
You would probably want to add a sleep between prints to be able to actually see the text changing...
When you use the print function in python, you're just pushing characters onto a pipe somewhere (the pipe might be connected to the standard out, but your program doesn't know that). Once its, pushed, there is nothing you can do to un-push it. Afterall, the pipe might not even be connected to a screen. It might be directly connected to the input of another program, or it might be using a physical printer for display. What would un-pushing even mean in those cases?
There are, however, special control characters (such as the "backspace" character) that you push to the pipe to signal that you want to erase characters. However, The terminal you are connected to is free to do what it wants with these characters. It can respect your wishes and erase characters, or it can print the literal '\b' characters to indicate a backspace, or it can completely ignore you and continue to print after the previous letters. That's completely out of your control.
Assuming the terminal that print the characters supports overwriting the characters, you can use the ANSI control sequences. The sequence for moving cursor to beginning of line is '\033[1G' and for erasing the everything from current cursor position to end of line is '\033[0K'. So,
import time
print('hello world', end='', flush=True) # prints "hello world" with no newline at the end
time.sleep(2) # wait 2 seconds
print('\033[1G\033[0K', end='') # moves cursor to beginning of line and erases the line
print('hi') # prints "hi" with newline at the end
flush=True is needed because the print function is buffered by default and doesn't actually print anything until it hits a newline. This tells the function you want to flush the buffer immediately.
Take a look at ANSI escape codes, section on "CSI sequences" to see what other codes are available.
I have a bit of code from a class which prints a line, and every line is followed by an empty line.
Is there a way to adjust the following code so that I don't have to have those empty lines?
def bfield(self):
self.n=0
for i in self.whole:
for j in i:
print("{:>4}".format(j), end='')
self.n=self.n+1
if self.n==len(i):
print('\n')
self.n=0
I'll agree with Rahul Chowdhury, remove the \n. Pythons print command, by default, will always start a new line after each print call. Hence your addition of '\n' will always result in an empty line.
If you wanted to look into how to get around the whole newline thing python does (every call in its own line), I found this link for you. It is fairly simple to do!
EDIT: It just occurred to me I should maybe list a few of the options just in case the link goes down. Here is one example:
print("Hello ", end = '')
print("World!")
With this, you overwrite the usual python lineend with your end = '' argument.
Another option would be to use the sys library
import sys
and then call the stdout.write() function, like so:
sys.stdout.write("Hello ")
sys.stdout.write("World!")
I just want to know why it's doing this, and how to fix it.
I've tried changing the screen size and it still doesn't work.
Any Ideas?
If you try to run the code, choose option C as that's the one that doesn't work for me. It's meant to print off all the moderate/high client's times, but it puts the total time on a new line.
Code + files:
Text file
Python code
Print statements automatically append "\n" to the end of the statement. This ensures that the next print statement will write to a new line instead of on the previous line.
If you want to prevent this, you can use this parameter:
print("This is a: ", end="")
print("message")
Notice the end="" on the first print statement. This will output
This is a: message
If that doesn't solve your issue, I suggest taking a close look at the text you're printing. Make sure that none of the lines have a "\n". Note that reading text from a .txt file will yield lines that automatically have "\n" appended to them.
I'm writing a program in python and I'd like to replace more than one line in the console with new text.
For example if I have 3 sentences printed to the console with:
print("Hello World!")
print("How are you!")
print("What's going on?")
Where each on is on a different line (and so has an \n).
How do I go about replacing all of this text when it displays in the console? I can't us \r in this situation due to the \n.
This is kind of an old post, but I came across it and worked out a solution as well. Added a timer, because otherwise the print statements bury each other and you'll only be able to read the last one. I'm on python 2.7:
import os
import time
os.system("printf 'Hello World!'")
time.sleep(1)
os.system("printf '\rHow are you?!'")
time.sleep(1.5)
os.system("printf '\rWhats going on?'")
os.system("echo ")
A simple fix would be to simply change the end separator for printing your strings. you can specify how you want the print function to separate calls with the end argument
print("hello world!", end="")
print("\rhello world again!")
In this case, we're setting the separator to "", which is nothing. So printing the next strings starts on the same line thus \r can be used. Compiling that gives you hello world again! on one line.