python - Pandas one-liner 加入系列元素

Question

我在玩 Pandas 方法时遇到了一个问题。
我可以用逗号加入 Pandas 系列的元素吗？
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j = {
  "locations": [
    {"name": "Seattle", "state": "WA"},
    {"name": "New York", "state": "NY"},
    {"name": "Bellevue", "state": "WA"},
    {"name": "Olympia", "state": "WA"}
  ]
}

df = pd.DataFrame(j['locations'])
ans = df.query("state=='WA'")['name'].sort_values()[-2:]

ans = df.query("state=='WA'")['name'].sort_values()[-2:].pipe(str.join) # this is my attempt but it does not work

必答

'Olympia, Seattle'

# NOTE:
obviously I can do ', '.join(ser.values)
but I am looking for pipe method.

Answer 1

import pandas as pd
j = {
  "locations": [
    {"name": "Seattle", "state": "WA"},
    {"name": "New York", "state": "NY"},
    {"name": "Bellevue", "state": "WA"},
    {"name": "Olympia", "state": "WA"}
  ]
}

df = pd.DataFrame(j['locations'])

ans = df.query("state=='WA'")['name'].sort_values()[-2:]
ans.pipe(', '.join)