pandas 使用函数在pandas df中添加一列
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Adding a column in pandas df using a function
提问by RageAgainstheMachine
I have a Pandas df [see below]. How do I add values from a function to a new column "price"?
我有一个 Pandas df [见下文]。如何将函数中的值添加到新列“价格”？
function:
def getquotetoday(symbol):
yahoo = Share(symbol)
return yahoo.get_prev_close()
df:
Symbol Bid Ask
MSFT 10.25 11.15
AAPL 100.01 102.54
(...)
回答by scomes
In general, you can use the apply function. If your function requires only one column, you can use:
通常，您可以使用 apply 函数。如果您的函数只需要一列，您可以使用：
df['price'] = df['Symbol'].apply(getquotetoday)
as @EdChum suggested. If your function requires multiple columns, you can use something like:
正如@EdChum 建议的那样。如果您的函数需要多列，您可以使用以下内容：
df['new_column_name'] = df.apply(lambda x: my_function(x['value_1'], x['value_2']), axis=1)
