Invert nested table-in-table hierarchy in tables or timetables
T2 = inner2outer( finds the variables
T1 that are themselves tables or timetables. It returns
T2, a table or timetable that also contains nested tables or
timetables as variables. The names of the variables in
taken from the names of the variables inside the nested tables or timetables of
inner2outer regroups variables
in the nested tables or timetables of
T2 appropriately, as shown
in the diagram. If
T1 has variables that are not tables or
timetables, then those variables are unaltered in
Invert Nested Tables
Load and display a timetable,
T1, that has nested tables containing stock information. The nested tables
MSFT are the variables of
T1. Each nested table has the stock prices at the open and close of trading, and the volume, for a different company.
load nestedTables T1
T1 = 3x2 timetable Dates AAPL MSFT Open Close Volume Open Close Volume ___________ __________________________ __________________________ 01-Jan-2017 64.539 71.704 107.17 66.429 91.77 78.7 01-Feb-2017 101.53 87.619 57.909 72.984 84.629 57.959 01-Mar-2017 60.381 76.464 72.067 78.127 76.492 82.883
To group the
Volume variables together in nested tables of their own, use the
T2 = inner2outer(T1)
T2 = 3x3 timetable Dates Open Close Volume AAPL MSFT AAPL MSFT AAPL MSFT ___________ ________________ ________________ ________________ 01-Jan-2017 64.539 66.429 71.704 91.77 107.17 78.7 01-Feb-2017 101.53 72.984 87.619 84.629 57.909 57.959 01-Mar-2017 60.381 78.127 76.464 76.492 72.067 82.883
Some calculations are more convenient with data from each stock grouped in the nested tables of
T2. For example, you can calculate the normalized volume for all stocks using
Variables property of
T2 to convert
T2.Volume into a matrix. Then subtract the mean of
T2.Volume and return the result as a matrix.
normVolume = T2.Volume.Variables - mean(T2.Volume.Variables)
normVolume = 28.1213 5.5193 -21.1397 -15.2217 -6.9817 9.7023
You also can use table functions on the nested tables. Calculate the mean closing price of all stocks using the
varfun function, returning the means in a table.
meanClose = varfun(@mean,T2.Close)
meanClose = 1x2 table mean_AAPL mean_MSFT _________ _________ 78.596 84.297
T1 — Input table
table | timetable
Input table, specified as a table or timetable.
Calculate with arrays that have more rows than fit in memory.
This function fully supports tall arrays. For more information, see Tall Arrays.
Run code in the background using MATLAB®
backgroundPool or accelerate code with Parallel Computing Toolbox™
This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.