Why won't Matlab recognize my data?

Question

econogist 2022-4-15

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1697690-why-won-t-matlab-recognize-my-data

评论： Walter Roberson 2022-4-15

multiTimeline.csv

I am trying to plot CSV data (attached) on Google search trends, but the date (year and month) is only appearing as "NaN." How do I plot this?

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Answer 1

Voss 2022-4-15

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https://ww2.mathworks.cn/matlabcentral/answers/1697690-why-won-t-matlab-recognize-my-data#answer_943800

在 MATLAB Online 中打开

multiTimeline.csv

The answer depends on how you're reading the file and how you want to deal with the cells in column 2 that say "<1".

One way to do it using readtable:

T = readtable('multiTimeline.csv')

Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.

T = 220×2 table

Month universalBasicIncome__UnitedStates_ ___________ ___________________________________ {'2004-01'} 5 {'2004-02'} 0 {'2004-03'} 0 {'2004-04'} 0 {'2004-05'} 0 {'2004-06'} 5 {'2004-07'} 0 {'2004-08'} 0 {'2004-09'} 0 {'2004-10'} 0 {'2004-11'} 0 {'2004-12'} 0 {'2005-01'} 0 {'2005-02'} 3 {'2005-03'} 0 {'2005-04'} 0

plot(datetime(T.Month,'InputFormat','yyyy-MM'),T.universalBasicIncome__UnitedStates_)

One way to do it using readcell:

C = readcell('multiTimeline.csv')

C = 222×2 cell array

{'Category: All categories'} {1×1 missing } {'Month' } {'universal basic income: (United States)'} {'2004-01' } {[ 5]} {'2004-02' } {[ 0]} {'2004-03' } {[ 0]} {'2004-04' } {[ 0]} {'2004-05' } {[ 0]} {'2004-06' } {[ 5]} {'2004-07' } {[ 0]} {'2004-08' } {[ 0]} {'2004-09' } {[ 0]} {'2004-10' } {[ 0]} {'2004-11' } {[ 0]} {'2004-12' } {[ 0]} {'2005-01' } {[ 0]} {'2005-02' } {[ 3]}

C([1 2],:) = []; % remove header rows

idx = ~cellfun(@isnumeric,C(:,2)); % replace "<1" or any other

C(idx,2) = {NaN}; % non-numeric entry with a NaN

plot(datetime(C(:,1),'InputFormat','yyyy-MM'),vertcat(C{:,2}));

There are other ways.

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Answer 2

Walter Roberson 2022-4-15

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1697690-why-won-t-matlab-recognize-my-data#answer_943795

在 MATLAB Online 中打开

filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/965680/multiTimeline.csv';
opt = detectImportOptions(filename, 'PreserveVariableNames', true);
opt = setvartype(opt, 1, 'datetime');
opt = setvaropts(opt, 1, 'InputFormat', 'yyyy-MM');
T = readtable(filename, opt);
T(1:2,:)
ans = 2×2 table
     Month     universal basic income: (United States)
    _______    _______________________________________

    2004-01                       5                   
    2004-02                       0                   