AppendColumns replaced the FlattenArray & Join

Questions
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1

Can someone please give me an example of how to replace AppendColumn with whatever it is replaced with. I looked at the documentation for both FlattenArray and Join but did not see anything concerning AppendColumns. My attempt to use the AppendRows example didn’t work (i.e.
http://reference.wolfram.com/mathematica/Compatibility/tutorial/LinearAlgebra/Files/MatrixManipulation.en/legacy\_1.gif )

In my above attempt I am just guessing that the problem was related to some simple list manipulation rule. I am a statistician and have been using SAS & R for many years so my brain thinks all math software processes a matrix of information row-wise.

Thanks,

Steve

2

A couple of ways to append the column col to mat.

In[1]:= mat = Partition[Range[12], 4]

Out[1]= {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}}

In[2]:= col = {1, 1, 1};

In[3]:= Transpose[Join[Transpose[mat], {col}]]

Out[3]= {{1, 2, 3, 4, 1}, {5, 6, 7, 8, 1}, {9, 10, 11, 12, 1}}

In[4]:= Join[mat, List /@ col, 2]

Out[4]= {{1, 2, 3, 4, 1}, {5, 6, 7, 8, 1}, {9, 10, 11, 12, 1}}