如何用值列表压平字典？

Question

我正在尝试“展平”字典，如下所示：

d = {
    "USA": ["US", "United States"],
    "SGP": ["JP", "Japan", "Singapore"]
}

我想把它变成这样的格式：

new_d = {
    "United States": "USA",
    "US": "USA",
    "JP": "SGP",
    "Japan": "SGP",
    "Singapore": "SGP"
}

Answer 1

使用带嵌套迭代的字典理解：

>>> d = {
...     "USA": ["US", "United States"],
...     "SGP": ["JP", "Japan", "Singapore"]
... }
>>> {i: k for k, v in d.items() for i in v}
{'US': 'USA', 'United States': 'USA', 'JP': 'SGP', 'Japan': 'SGP', 'Singapore': 'SGP'}

• k, v in d.items() -> k = "USA", ..., v = ["US", "United States"], ...
• i in v -> i = "US", ...

因此：

• {i: k ...} -> {"US": "USA", ...}