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

Created by Cody Team

Solve Later

{"relationships":[{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/document","targetMode":"","relationshipId":"rId1","target":"/matlab/document.xml"},{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/output","targetMode":"","relationshipId":"rId2","target":"/matlab/output.xml"}],"parts":[{"partUri":"/matlab/document.xml","relationship":[],"contentType":"application/vnd.mathworks.matlab.code.document+xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<w:document xmlns:w=\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\"><w:body><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>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).</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>The first row is always descriptive text. So if the input cell array s is</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[ s = { ...\n    'Day  Temp'\n    '  1   -5'\n    '  2   19'\n    '  3   1'\n    '  4   9999'\n    '  5   3'};]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>then the output variable t is the following row vector.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[ t = [-5 19 1 2 3];]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Here's an example of</w:t></w:r><w:r><w:t> </w:t></w:r><w:hyperlink w:docLocation=\"http://www.ndbc.noaa.gov/view_text_file.php?filename=41nt1h2008.txt.gz&amp;dir=data/historical/stdmet/\"><w:r><w:t>real-world data</w:t></w:r></w:hyperlink><w:r><w:t>.</w:t></w:r></w:p></w:body></w:document>"},{"partUri":"/matlab/output.xml","contentType":"text/xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?><embeddedOutputs><metaData><evaluationState>manual</evaluationState><layoutState>code</layoutState><outputStatus>ready</outputStatus></metaData><outputArray type=\"array\"/><regionArray type=\"array\"/></embeddedOutputs>"}]}

Solve

Solution Stats

6950 Solutions
1899 Solvers

Last Solution submitted on Apr 02, 2023

Last 200 Solutions

Problem Comments

8 Comments

8 Comments

Show 5 older comments

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

Solution Comments

Solution 6548744

Solution 6081698

2 Comments

2 Comments

Melissa Niesen on 8 Jul 2021

This made me realize I need to learn more about cells!

alex am on 8 Dec 2022

Nice one, the fillmissing saves a lot of messing with interp1!

Solution 2064693

1 Comment

1 Comment

Shlomo Geva on 20 Dec 2019

This solution actually fails on the assertion when using the following test (my own). It happens because of computational precision produced from using linspace() // out by about 0.222 * 1.0e-15.
s = { ...
'Day Temp'
' 1 1.3'
' 5 9999'
' 6 9999'
' 5 9999'
' 6 9999'
' 2 1.12'
' 3 17'
' 4 16'
' 5 9999'
' 6 9999'
' 7 19'};
t_correct = [1.3 1.264 1.228 1.1920 1.156 1.12 17 16 17 18 19];
assert(isequal(read_and_interp(s),t_correct));

Solution 858987

2 Comments

2 Comments

eggart on 30 Mar 2016

my standalone MATLAB function works just fine -- but cody complains by
"Error using SharedVariable1 (line 11)
Assertion failed."
I cannot make heads or tails of it. Any help?

Aditya Jain on 26 Oct 2016

Check the test suite. There was an issue with the displaying of test suite.

Solution 346118

1 Comment

1 Comment

Heather on 6 Nov 2013

Sorry about all the incorrect solutions just before this, but Cody was throwing errors that my Matlab installation wasn't.

Problem Recent Solvers1899

Problem Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

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

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers1899

Suggested Problems

More from this Author96

Problem Tags

Community Treasure Hunt

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

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers1899

Suggested Problems

More from this Author96

Problem Tags

Community Treasure Hunt

Players