Operations on multiple Dataframes in Python

Question

Data frames are provided:

a = pd.DataFrame({'A':[1, 2]})
b = pd.DataFrame({'B':[2, 3]})
C = pd.DataFrame({'C':[4, 5]})

and list d = [A, C, B, B]

How to write an mathematical operations (((A + C) * B) - B) on frame values to create a new data frame?

The result is, for example, a frame in the form:

e = pd.DataFrame({'E':[8, 18]})

You could also just do (a.A + C.C) * b.B - b.B quite simply. — cs95
– cs95, Commented Nov 19, 2017 at 22:26
No problem. I still like Max's solution better, because it offers you much more flexibility. — cs95
– cs95, Commented Nov 19, 2017 at 22:32
@cᴏʟᴅsᴘᴇᴇᴅ And I'm still trying with the previous problem. I think he can do just that. Theoretically, I have only one function, let's assume that the solution to my problem would be to create a loop with the function ((A * B) * C) * A) and so on. Because in that solution the code gives separate solutions for each element, comparing them still to the first one :) — Tomasz Przemski
– Tomasz Przemski, Commented Nov 19, 2017 at 22:40

MaxU - stand with Ukraine · Accepted Answer · 2017-11-19 22:21:43Z

5

IIUC:

In [132]: formula = "E = (((A + C) * B) - B)"

In [133]: pd.concat([a,b,C], axis=1).eval(formula, inplace=False)
Out[133]:
   A  B  C   E
0  1  2  4   8
1  2  3  5  18

In [134]: pd.concat([a,b,C], axis=1).eval(formula, inplace=False)[['E']]
Out[134]:
    E
0   8
1  18

answered Nov 19, 2017 at 22:21

MaxU - stand with Ukraine

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