查找、替换和连接字符串

Question

在5年多的不活动之后，我正在重新（学习）python；虽然我一开始并不擅长，但这并没有帮助… 以下是我想做的：

1. 在文件中找到一个sting并用另一个字符串替换它（G00和G1）
2. 查找行以特定字符串开头的所有实例，并在其末尾连接一个字符串
3. 原始文件aaaa.gcode保持不变，所有更改都保存到bbbb.gcode

这两组代码各自按预期工作。我尝试了很多不同的方法来将这两组代码添加到一起，但都不起作用

示例文件（C:\gcode\aaaa.gcode）

# start of file
some text
other text

# more text
G00 X1 Y1
G00 X2 Y2
# other text
G00 X3 Y3
G00 X4 Y4

#end of file

对于最终结果，我希望：

# start of file
some text
other text

# more text
G1 X1 Y1 Z0.3
G1 X2 Y2 Z0.3
# other text
G1 X3 Y3 Z0.3
G1 X4 Y4 Z0.3

#end of file

示例代码/结果

1. 查找并用G1替换-G00

Code:
    with open(r'C:\gcode\aaaa.gcode', 'r') as fin, open(r'C:\gcode\bbbb.gcode', 'w') as fout:
    for line in fin:
        if line.startswith('G00'):
            fout.write(line[:-1] + ' Z0.3' + '\r')
        else:
            fout.write(line)

Result:
# start of file
some text
other text

# more text
G1 X1 Y1
G1 X2 Y2
# other text
G1 X3 Y3
G1 X4 Y4

#end of file

1. 连接字符串-如果行以G00开头，则添加Z0.3

Code:
    with open(r'C:\gcode\aaaa.gcode', 'r') as fin, open(r'C:\gcode\bbbb.gcode', 'w') as fout:
        for line in fin:
            if line.startswith('G00'):
                fout.write(line[:-1] + ' Z0.3' + '\r')
            else:
                fout.write(line)

Result
# start of file
some text
other text

# more text
G00 X1 Y1 Z0.3
G00 X2 Y2 Z0.3
# other text
G00 X3 Y3 Z0.3
G00 X4 Y4 Z0.3

#end of file

我尝试了下面代码的各种分支，但始终收到以下错误消息：

with open(r'C:\gcode\aaaa.gcode', 'r') as fin, open(r'C:\gcode\bbbb.gcode', 'w') as fout:
    for line in fin:
        if line.startswith('G00'):
            fout.write(line[:-1] + ' Z0.3' + '\r')
            fout = fout.replace('G00', 'G1')   # newly added line
        else:
            fout.write(line)

AttributeError: '_io.TextIOWrapper' object has no attribute 'replace'

Answer 1

您试图在文件句柄上执行.replace-这没有意义，您应该在line上执行，例如：

with open(r'C:\gcode\aaaa.gcode', 'r') as fin, open(r'C:\gcode\bbbb.gcode', 'w') as fout:
    for line in fin:
        line = line.replace('G00', 'G1')
        if line.startswith('G00'):
            fout.write(line[:-1] + ' Z0.3' + '\r')
        else:
            fout.write(line)

还要注意，当且仅当行以\r分隔时，代码才能正常工作

Answer 2

您不能从fout替换，您需要替换行的内容。这也不理解为什么你要开始与fout.replace('G00', 'G1') # newly added line相等。试试这个：

with open(r'C:\gcode\aaaa.gcode', 'r') as fin, open(r'C:\gcode\bbbb.gcode', 'w') as fout:
    for line in fin:
        if line.startswith('G00'):
            fout.write(line[:-1] + ' Z0.3' + '\r')
            new_line = line('G00', 'G1')   # newly added line
            # I believe you're trying to add this new line to the document
            fout.write(new_line)
        else:
            fout.write(line)