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based on an earlier version of the Wolfram Language.
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# Rearranging Nested Lists

You will encounter nested lists if you use matrices or generate multidimensional arrays and tables. Mathematica provides many functions for handling such lists.
 Flatten[list] flatten out all levels in list Flatten[list,n] flatten out the top n levels in list Partition[list,{n1,n2,...}] partition into blocks of size n1×n2×... Transpose[list] interchange the top two levels of lists RotateLeft[list,{n1,n2,...}] rotate successive levels by ni places PadLeft[list,{n1,n2,...}] pad successive levels to be length ni

A few functions for rearranging nested lists.

This "flattens out" sublists. You can think of it as effectively just removing all inner braces.
 Out[1]=
This flattens out only one level of sublists.
 Out[2]=
There are many other operations you can perform on nested lists. We will discuss more of them in "Manipulating Lists".