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

Created by Cody Team

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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 May 09, 2025

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James Kristoff on 17 Aug 2016

Cody keeps throwing the error "Error using SharedVariable1 (line 11) Assertion failed." no matter what code is submitted.

mItk on 26 Oct 2016

Seems the test suite always calls the function with the same cell array 'Day Temp' ' 1 1.3' ' 2 1.12' ' 3 17' ' 4 -32' ' 5 13' ' 6 4.4' ' 7 19'.

Aditya Jain on 26 Oct 2016

I have fixed an issue with this problem where the test suite was not visible since there was no %% for the first test suite

shahriar memaran on 15 Mar 2017

keeps throwing Error for me too. Even though the answers are I get are the same as the test suite.

David Verrelli on 12 Mar 2018

I suggest that there should have been some cases with more than one 'run' of 9999 values in the Test Suite, just as in the "real-world data". For example: clean for an input based on [100 100 9999 9999 100 200 9999 300 500], which has two (not three) 'runs'. (Testing interpolation with nil slope, as in this example, would also have been good to include.)

Sanzhar Askaruly on 21 Jul 2019

the problem makes you sweat, awesome!

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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