Question

I have two lists-of-lists which can be schematically summarized by this:

a = {{1}, {2}, {3}};
b = {{4}, {5}, {6}};

I want to combine them into a single list of lists, with each element at the same level, ala:

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

Except I cannot for the life of me make it happen. The most obvious thing looks like:

In[537]:= Append[a, b]
Out[537]= {{1}, {2}, {3}, {{4}, {5}, {6}}}

Which isn’t what I want. The Append documentation doesn’t seem to cover a case like this, and I can get no amount of Appending and Flattening to work. I suppose I could write a for loop and just keep adding to an empty list, but good god is that clumsy. There must be an elegant way to do it?

Answer 1

Change your code from:

In[537]:= Append[a, b]

to:

In[537]:= Join[a, b]