Adding a column in pandas df using a function

Question

I have a Pandas df [see below]. How do I add values from a function to a new column "price"?

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
...

d-cubed · Accepted Answer · 2019-12-31 16:11:19Z

93

In general, you can use the apply function. If your function requires only one column, you can use:

df['price'] = df['Symbol'].apply(getquotetoday)

as @EdChum suggested. If your function requires multiple columns, you can use something like:

df['new_column_name'] = df.apply(lambda x: my_function(x['value_1'], x['value_2']), axis=1)

edited Dec 31, 2019 at 16:11

d-cubed

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answered Oct 14, 2016 at 14:37

scomes

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Comments

wjandrea · Accepted Answer · 2023-09-24 23:16:15Z

0

Alternatively you can use pipe:

df['price'] = df['Symbol'].pipe(getquotetoday)

edited Sep 24, 2023 at 23:16

wjandrea

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answered Jul 2, 2022 at 17:39

rachwa

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1 Comment

wjandrea Over a year ago

This assumes Share works on a Series. Is that reasonable? I'm not familiar with whatever library OP's using. If it is, why bother when you could just do df['price'] = getquotetoday(df['Symbol'])? If it isn't, maybe you're thinking of map?

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