Create a datastore for theAirlinesMall.CSV数据集。选择一个可使用的变量子集，然后处理'NA'values as missing data so that数据store取代它们NaNvalues. Convert the datastore into a tall table.

varnames = {“年”,'ArrDelay',“唯一载体”}; ds = datastore('airlinesmall.csv','TreatAsMissing','NA',...'SelectedVariableNames'，varnames）;T =高（DS）

t = m×3个高桌年ard ardelay独立赛车____ _________________________ 1987 8'ps'1987 8'ps'1987 21'ps'1987 13'ps'1987 4'ps'ps'1987 59'ps'ps'ps'1987 3'ps'ps'ps'ps'1987 1987 1987 11 11'ps'::：：：：：

Calculate the size of the tall table.

sz = size(T)

SZ = 1×2高的双行矢量？？

MATLAB® does not immediately evaluate most operations on tall arrays. Instead, MATLAB remembers the operations you perform as you enter them and optimizes the calculations in the background.

When you usegatheron an unevaluated tall array, MATLAB executes all of the queued operations using the minimum number of passes through the data. This optimization greatly reduces the execution time of large calculations. For this reason, you should usegatheronly when you need to see a result.

Usegatherto execute the calculation and collect the result into memory.

s =gather(sz)

Evaluating tall expression using the Local MATLAB Session: - Pass 1 of 1: Completed in 0 sec Evaluation completed in 0 sec

s =123523 3

Usegatherwith several inputs to simultaneously evaluate several tall arrays.

Create a tall array from an in-memory array of random integers between 1 and 1000. Calculate the maximum and minimum values in each column.

A = tall(randi(1000,100,7))

a = 100×7高双矩阵815 163 645 60 423 583 583 851 906 795 379 682 95 541 541 561 561 127 312 812 43 599 870 930 914 914 914 914 914 529 529 533 72279 263 876 819 639 940 880 547 655 551 818 34 646 989：：：：：：：：：:: :: :: :: ::: ::: ::: ::: ::: ::: ::: ::: ::: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :：

b = min(A); c = max(A);

Use the results to determine the overall minimum and maximum values in the array. Collect the final result into memory.

[mna，mxa] =收集（min（b），max（c））;

Evaluating tall expression using the Local MATLAB Session: Evaluation completed in 0 sec

valrange =[mnA mxA]

valrange =1 1000