您有几种选择可以遍历字典。
如果迭代字典本身（
for team inleague），则将迭代字典的键。当使用for循环进行循环时，无论您是在dict（
league）本身上循环还是在以下情况下，行为都是相同的
league.keys()：
for team in league.keys(): runs_scored, runs_allowed = map(float, league[team])
您还可以通过迭代遍历键和值一次
league.items()：
for team, runs in league.items(): runs_scored, runs_allowed = map(float, runs)
您甚至可以在迭代时执行元组拆包：
for team, (runs_scored, runs_allowed) in league.items(): runs_scored = float(runs_scored) runs_allowed = float(runs_allowed)
