creating a dummy variable combining other dummies in python

Question

I want to combine three dummy variables into one. For example:

x1: 1 0 0 0 1

x2: 0 0 0 0 1

x3: 1 1 0 0 0

I want to create: x4: 1 1 0 0 1 (Takes 1 if any of the three dummies has 1, and takes 0 if all of them are zero)

Note: They are variables in a data frame. So the new variable will be a part of that data frame too.

I am new in python and I appreciate your help. Best

Answer 1

Let's say you define x as a grid:

x = [
    [1, 0, 0, 0, 1],
    [0, 0, 0, 0, 1],
    [1, 1, 0, 0, 0]
]

For each row, we can use any() to see if any of the items in the row is one. We can then turn the result (a boolean) into an integer with int() :

result = [int(any(row)) for row in x]

Answer 2

I'm not so sure what you mean by the new variable being part of the data frame.

I think the most literal way to create x4 is by using a bitwise OR operator in a list comprehension:

>>> x1=[1, 0, 0, 0, 1]
>>> x2=[0, 0, 0, 0, 1]
>>> x3=[1, 1, 0, 0, 0]
>>> x4=[x1[i]|x2[i]|x3[i] for i in range(len(x1))]
>>> x4
[1, 1, 0, 0, 1]

The list comprehension (see https://docs.python.org/3/tutorial/datastructures.html#list-comprehensions ) builds a new list while iterating over the first, second, etc values of x1-x3. The bitwise OR operator (|) (see https://wiki.python.org/moin/BitwiseOperators ) each time evaluates to 1 if any of the 3 values is 1 and to 0 otherwise.