Problem 71. Read a column of numbers and interpolate missing data

Created by Cody Team
Appears in Matrix Manipulation I

Difficulty:Rate

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Given an input cell array of strings s, pick out the second column and turn it into a row vector of data. Missing data will be indicated by the number 9999. If you encounter missing data, you should perform linear interpolation to the nearest accurate data points (missing data will not occur in the first or last element).

The first row is always descriptive text. So if the input cell array s is

 s = { ...
    'Day  Temp'
    '  1   -5'
    '  2   19'
    '  3   1'
    '  4   9999'
    '  5   3'};

then the output variable t is the following row vector.

 t = [-5 19 1 2 3];

Here's an example of real-world data.

Solve

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Last Solution submitted on Feb 20, 2025

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Umur Ulas Harman on 31 Jul 2020

This is working still would be appreciated for enhancement.

function t = read_and_interp(s)
s=strtrim(s);
row_num=numel(s);
counter=1;
for i=2:row_num
splitted=strsplit(s{i});
temp1=splitted(1);
temp2=splitted(2);
r(counter)=str2double(temp1);
r(counter+1)=str2double(temp2);
counter=counter+2;
end
first_column=r(1:2:end)
second_column=r(2:2:end)
if find(second_column==9999)>=1
first_column(find(second_column==9999))=[];
missed=find(second_column==9999);
second_column(find(second_column==9999))=[];
missed_value=interp1(first_column,second_column,missed)
second_column=r(2:2:end);
second_column(find(second_column==9999))=missed_value;
t=second_column
else
t=second_column
end

Ahmed Nazir on 1 Oct 2020

Good Problem

beware of splitting.

solution:
https://github.com/AhmedNazir/MatlabCody/blob/master/read_and_interp.m

Peter on 18 Aug 2023

Interesting!

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Problem 71. Read a column of numbers and interpolate missing data

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Problem 71. Read a column of numbers and interpolate missing data

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