61 lines
1.4 KiB
Markdown
61 lines
1.4 KiB
Markdown
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# Exercise 5.3 - Solution
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## (a) Higher order functions
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```python
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# reader.py
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import csv
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def convert_csv(lines, converter, *, headers=None):
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records = []
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rows = csv.reader(lines)
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if headers is None:
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headers = next(rows)
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for row in rows:
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record = converter(headers, row)
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records.append(record)
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return records
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def csv_as_dicts(lines, types, *, headers=None):
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return convert_csv(lines,
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lambda headers, row: { name: func(val) for name, func, val in zip(headers, types, row) })
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def csv_as_instances(lines, cls, *, headers=None):
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return convert_csv(lines,
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lambda headers, row: cls.from_row(row))
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def read_csv_as_dicts(filename, types, *, headers=None):
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'''
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Read CSV data into a list of dictionaries with optional type conversion
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'''
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with open(filename) as file:
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return csv_as_dicts(file, types, headers=headers)
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def read_csv_as_instances(filename, cls, *, headers=None):
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'''
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Read CSV data into a list of instances
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'''
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with open(filename) as file:
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return csv_as_instances(file, cls, headers=headers)
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```
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## (b) Using map()
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```python
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# reader.py
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import csv
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def convert_csv(lines, converter, *, headers=None):
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records = []
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rows = csv.reader(lines)
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if headers is None:
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headers = next(rows)
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return map(lambda row: converter(headers, row), rows)
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```
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[Back](ex5_3.md)
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