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118 lines
3.3 KiB
118 lines
3.3 KiB
5 years ago
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""" data logger """
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from pathlib import Path
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CR = chr(13)
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LF = chr(10)
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def is_container(obj):
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"""' checks if the object is iterable but not string or bytes """
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return hasattr(obj, "__iter__") and not isinstance(obj, (str, bytes))
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class DataLogger:
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def __init__(self, log_path, none_rep="", sep="\t", end=CR + LF):
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""" initializes the data logger class
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:params log_path: file path of the log file
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:params none_rep: string representation for None values
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:params sep: character used to separate values in a list
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:params end: character used for line ending
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"""
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self.path = Path(log_path)
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self.end = end
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self.sep = sep
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self.none_rep = none_rep
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self.handle = None
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def open(self):
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""" opens the log file for writing """
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if self.handle is None:
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self.path.parent.mkdir(parents=True, exist_ok=True)
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self.handle = self.path.open("a")
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def close(self):
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""" closes the log file for writing """
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if self.handle:
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self.handle.close()
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self.handle = None
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def __call__(self, data):
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""" writes data to the log
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:params data: either a string or a container, like a list
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"""
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if is_container(data):
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self.add_list(data)
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else:
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self.add(data)
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def add(self, text):
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""" adds one line of text to the logfile """
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if self.handle is None:
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raise IOError("Log file not opened for writing")
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text = self._universal_new_lines(text)
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self.handle.write(text)
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def add_list(self, data):
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""" adds the values in a list to one line in the log FileCache
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The string set in the `sep` property is used to separate the values
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in the output, None values are represented by the string in `none_rep`
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property.
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"""
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conveted_nones = ((self.none_rep if v is None else v) for v in data)
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value_strings = (str(v) for v in conveted_nones)
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line = self.sep.join(value_strings)
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self.add(line)
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def add_section(self, title, list_of_data, append_empty_line=True):
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""" adds a section to the log file """
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title = title.strip()
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self.add(f"[{title}]")
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for data in list_of_data:
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self.add_list(data)
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if append_empty_line:
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self.add("")
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def __enter__(self):
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""" Context manager: opens the log file for writing """
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self.open()
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return self
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def __exit__(self, exc_type, exc_value, exc_traceback):
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""" Context manager: closes the log file """
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self.close()
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def _universal_new_lines(self, text):
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""" unifies new line characters of a text
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The `end` property is used as a newline character and ensures one is
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present at the end of the text.
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"""
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lines = text.splitlines()
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return self.end.join(lines) + self.end
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class NullLogger:
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""" A stub logger with the DataLogger interface that does nothing """
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def __init__(self, *args, **kargs):
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pass
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def __call__(self, *args, **kargs):
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pass
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def __getattr__(self, key):
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return self
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def __enter__(self):
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return self
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def __exit__(self, *args, **kargs):
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pass
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