This is documentation for Mathematica 8, which was
based on an earlier version of the Wolfram Language.
How to | Work with Nested Lists
Nested lists are lists within a list; they are the principal structure for data in Mathematica and allow for high-dimension arrays and ragged datasets as well as common uses such as matrices.
Create a list of lists to work with:
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Matrices in Mathematica are represented as nested lists. Note that each row corresponds to a sublist in the nested list:
 Out[2]//MatrixForm=
Use , the short form of the Part function, to get the second row:
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From row 2, get element 3:
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Get element 3 from each row:
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Use Flatten to remove the nesting:
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Display the flattened data as a column:
 Out[7]//MatrixForm=
For comparison, to display the flattened data as a row, add :
 Out[8]//MatrixForm=

You can operate on the individual sublists of a nested list or on the nested list as a whole.
Set up a dataset:
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 Out[10]//MatrixForm=
Most functions map over each sublist within a nested list.
Create four plots from the rows in the dataset:
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Most descriptive statistics functions operate by columns.
Take the mean by column:
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Get the mean of all the numbers by flattening the list:
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Create a doubly nested list:
 Out[15]//MatrixForm=
Mean now lists the means by each individual nested sublist:
 Out[16]//MatrixForm=
Use Flatten to obtain the mean of the entire dataset:
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