How to clear the output of a specified area when the second progress bar appears in a Python script?

How to clear the previous output when the second progress bar appears in a Python script?

In Python scripts, especially when displaying progress bars or dynamic information, it is often necessary to clear the output of a specific area of ​​the terminal to keep the interface neat. This article will explain in detail how to clear the previous output area when the second progress bar is displayed.

The problem description mentioned that the script uses the inquirer library to handle user interaction and needs to clear the previous output when displaying the second progress bar. To solve this problem, we can use the \r character to return the previous output overriding the line header, or use ANSI escape code for finer control.

Method 1: Overwrite the output with \r characters

The \r character can move the cursor to the beginning of the current line, overwriting the previous text with the new output. Here is a simple example:

 import time

for i in range(10):
    print(f"{i=}", end="\r", flush=True) # flush=True Make sure to output time.sleep(1) immediately

This code updates the output of the same line every second, \r that each output covers the previous number. This method is simple and easy to use, but only works for overriding the same line of content.

Method 2: Use ANSI escape code to clear the specified area

ANSI escape codes allow more precise control of terminal output, including clearing screens or specific lines. The following function can clear the specified number of rows:

 import sys

def clear_lines(num_lines):
    for _ in range(num_lines):
        sys.stdout.write("\033[F\033[K") # \033[F: Move one line up; \033[K: Clear the current line

This function moves the cursor up one row through \033[F , \033[K clears the current row, and repeats num_lines to clear the output of the specified number of rows. To clear the entire screen, use sys.stdout.write("\033[2J\033[H") .

Method 3: Combining the inquirer library and ANSI escape code

During the interaction of the inquirer library, you can use the clear_lines function to clear the previous output before the second progress bar. The specific implementation needs to be adjusted according to the API of inquirer library, such as calling the clear_lines function to clear the specified number of rows before displaying the second progress bar.

Notes:

• The compatibility of ANSI escape code depends on the terminal type. Some terminals may not support these escape codes.
• Using flush=True ensures that the output is displayed immediately and avoids output lag.
• The clear_lines function only clears the text content and does not affect the cursor position. The cursor position needs to be adjusted according to the actual situation.

Through the above methods, the previous terminal output in Python scripts can be effectively cleared, thereby improving the user experience. Which method to choose depends on the specific requirements and end environment. If you need to clear multiple lines of content and have high requirements for terminal compatibility, it is recommended to use ANSI escape code. If you only need to clear the single line content, the \r character is easier.

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