How to use lambda to change the values in dataframe?

Question

I've tried to scale the values in the dataframe by a factor of 10 to the 6th power, but the results don't show any change.

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Energy['Energy Supply'].apply(lambda x: x*(10**6))
Energy.head()

enter image description here

Please note that in general, it is better to post example data / code as text instead of image - it's also more likely that you'll get a helpful answer then. — FObersteiner
– FObersteiner, Commented Feb 2, 2022 at 10:53
Regarding the Q, apply doesn't work in-place, you need to re-assign the returned series; Energy['Energy Supply'] = Energy['Energy Supply'].apply(lambda x: x*(10**6)). — FObersteiner
– FObersteiner, Commented Feb 2, 2022 at 10:54

3dSpatialUser · Accepted Answer · 2022-02-02 10:53:47Z

3

You have to add the = operator. DataFrames are not mutable like lists, therefore you have to store the value in the column: Energy['Energy Supply'] = ....

Energy['Energy Supply'] = Energy['Energy Supply'].apply(lambda x: x*(10**6))
Energy.head()

answered Feb 2, 2022 at 10:53

3dSpatialUser

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Corralien · Accepted Answer · 2022-02-02 11:05:08Z

3

You don't need to use apply, just use compound assignment operators:

Energy['Energy Supply'] *= 1e6

answered Feb 2, 2022 at 11:05

Corralien

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