Extracting values corresponding to exact date from a table and update it in another table on a same date

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Muhammad Haris Siddiqui
评论： Muhammad Haris Siddiqui 2021-11-4
Hello,
I have two tables with different number of rows.
I want to extract the values from table "ntt" from "VarName4" column as shown below.
and paste it in column 2 of table "C" as shown below corresponding to the exact date as in table "ntt". As table "C" have other dates for which I don't have data and want to leave it blank or with zeros.
I treid to use for loop for updating a table "C"
for k = 1:height(ntt)
p = ntt{k,"Rainfallmm"};
C(p,2) = ntt{k,"VarName4"};
end
but it gives me this error
"A table row subscript must be a numeric array containing real positive integers, a logical array, a character vector, a string array, or a cell array of character vectors"
any help would be appreciated.
Thanking you in anticipation

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采纳的回答

Seth Furman
Seth Furman 2021-11-4
Ran in:
1) Convert your tables to timetables
This isn't strictly necessary to answer your question, but is generally a good idea when working with tabular timestamped data.
% Example tables
Date = datetime(2021, 1, 1:10:100)';
t1 = table(Date, (1:10)')
t1 = 10×2 table
Date Var2 ___________ ____ 01-Jan-2021 1 11-Jan-2021 2 21-Jan-2021 3 31-Jan-2021 4 10-Feb-2021 5 20-Feb-2021 6 02-Mar-2021 7 12-Mar-2021 8 22-Mar-2021 9 01-Apr-2021 10
Date = datetime(2021, 1, 1:5:100)';
t2 = table(Date)
t2 = 20×1 table
Date ___________ 01-Jan-2021 06-Jan-2021 11-Jan-2021 16-Jan-2021 21-Jan-2021 26-Jan-2021 31-Jan-2021 05-Feb-2021 10-Feb-2021 15-Feb-2021 20-Feb-2021 25-Feb-2021 02-Mar-2021 07-Mar-2021 12-Mar-2021 17-Mar-2021
% Convert tables to timetables
t1 = table2timetable(t1)
t1 = 10×1 timetable
Date Var2 ___________ ____ 01-Jan-2021 1 11-Jan-2021 2 21-Jan-2021 3 31-Jan-2021 4 10-Feb-2021 5 20-Feb-2021 6 02-Mar-2021 7 12-Mar-2021 8 22-Mar-2021 9 01-Apr-2021 10
t2 = table2timetable(t2)
t2 = 20×0 empty timetable
https://www.mathworks.com/help/matlab/ref/table2timetable.html
2) Take a look at the functions (join, innerjoin, and outerjoin)
I suspect that you'll want outerjoin in your case.
outerjoin(t1, t2, "Keys", "Date")
ans = 20×1 timetable
Date Var2 ___________ ____ 01-Jan-2021 1 06-Jan-2021 NaN 11-Jan-2021 2 16-Jan-2021 NaN 21-Jan-2021 3 26-Jan-2021 NaN 31-Jan-2021 4 05-Feb-2021 NaN 10-Feb-2021 5 15-Feb-2021 NaN 20-Feb-2021 6 25-Feb-2021 NaN 02-Mar-2021 7 07-Mar-2021 NaN 12-Mar-2021 8 17-Mar-2021 NaN
https://www.mathworks.com/help/matlab/ref/outerjoin.html

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