Question

I have a mathematica list in which I want to replace all 2s with 1 and everything else to 0.

For example.

{0,1,2,3,2,3,4,5,2,2,6}

->

{0,0,1,0,1,0,0,0,1,1,0}

I assume it’s possible using replace all, but what rules would achieve this?

Thanks!

Answer 1

You can map the function (Boole[2 == #]) & onto the list.

In[2]:= (Boole[2 == #]) & /@ {0, 1, 2, 3, 2, 3, 4, 5, 2, 2, 6}
Out[2]= {0, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0}

Explanation of the different parts:

• /@ applies a function to each element on the list.
• The () & is the syntax used for anonymous functions, and the parameter the function takes is given the name #.
• The Boole converts True/False to 1/0.

So, in total, we create an anonymous function, which compares its input to 2, and gives either 0 or 1. This function is then mapped onto the list.