How do I extract the Datetime array from the CSV ?

Question

Cedric 2022-11-7

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1845523-how-do-i-extract-the-datetime-array-from-the-csv

回答： Star Strider 2022-11-7

I am trying to extract the Average Ice concentration and date time from the CSV file. I managed to extract the Average ice concentration, but for the date time it is extracting as individual cell arrays with datetime in eah cell as follows

I would want it to extract the datetime like this (from another project but cell2mat doesnot work here)

The cell2mat function doesnot work. I would want some recommendations on how to proceed.

The code is as follows

%% Importing data file

% Note: The text file has headers and two columns:

% Column 1 - example of entry: {[2010-12-16 0:00]}

% Column 2 - Ice concentration Min

% Column 3 - Ice concentration Average

% Column 4 - Ice concentration Max

%% Because these are two different data types, they need to be imported as a CELL ARRAY

B=readcell('Ice concentration data.csv'); % Note: The csv format is automatically recognized.

B(1:1,:) = []; % Removing top rows (headers)

%% From this array, we extract the Average Ice Concentration levels

% Average Ice Concentration levels - production of a one-column numeric matrix

average_ice_concentration_level = cell2mat(B(:,3));% Converting average ice concentration from numeric cell

% to numeric vector (matrix)

%% From the same array, we extract date, month, day

% Step 1: Production of a character vector matrix

date_ice_concentration = (B(:,1));

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Answer 1

Star Strider 2022-11-7

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1845523-how-do-i-extract-the-datetime-array-from-the-csv#answer_1093403

在 MATLAB Online 中打开

The readtable funciton imports it as a datetime array —

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1184228/Ice%20concentration%20data.csv')

T1 = 412×4 table

DateTime Conc_Ice_Min Conc_Ice_Avg Conc_Ice_Max ________________ ____________ ____________ ____________ 2010-12-16 00:00 3 8.2262 10 2010-12-18 00:00 4 8.6094 10 2010-12-21 00:00 0 5.5628 10 2010-12-23 00:00 0 6.2192 10 2010-12-27 00:00 0 8.2719 10 2010-12-28 00:00 0 9.4814 10 2010-12-29 00:00 3 9.4074 10 2010-12-30 00:00 0 8.5246 10 2010-12-31 00:00 0 7.944 10 2011-01-02 00:00 0 5.9938 10 2011-01-03 00:00 0 5.0078 10 2011-01-04 00:00 0 8.0016 10 2011-01-05 00:00 0 8.8131 10 2011-01-06 00:00 0 8.3935 10 2011-01-07 00:00 0 8.8402 10 2011-01-08 00:00 3 9.1284 10

T1.DateTime

ans = 412×1 datetime array

2010-12-16 00:00 2010-12-18 00:00 2010-12-21 00:00 2010-12-23 00:00 2010-12-27 00:00 2010-12-28 00:00 2010-12-29 00:00 2010-12-30 00:00 2010-12-31 00:00 2011-01-02 00:00 2011-01-03 00:00 2011-01-04 00:00 2011-01-05 00:00 2011-01-06 00:00 2011-01-07 00:00 2011-01-08 00:00 2011-01-09 00:00 2011-01-10 00:00 2011-01-11 00:00 2011-01-12 00:00 2011-01-13 00:00 2011-01-14 00:00 2011-01-15 00:00 2011-01-16 00:00 2011-01-17 00:00 2011-01-18 00:00 2011-01-20 00:00 2011-01-20 00:00 2011-01-22 00:00 2011-02-10 00:00

VN = T1.Properties.VariableNames;

lgdstr = cellfun(@(x)strrep(x,'_','\_'), VN(2:end), 'Unif',0)

lgdstr = 1×3 cell array

{'Conc\_Ice\_Min'} {'Conc\_Ice\_Avg'} {'Conc\_Ice\_Max'}

figure

plot(T1.DateTime, T1{:,2:end})

grid

legend(lgdstr, 'Location','best')

.