# Replacing values in a cell with NaN

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Caroline on 28 Jan 2017
Commented: Image Analyst on 29 Jan 2017
Hello community, I am new to Matlab, so still struggling with the apparently easy stuff. I have a 435x2 cell with text and numbers called "Data". The first column consists of text, the second column consists of numbers. My goal is to replace -1 values in the second column by NaN. What I have so far:
for i = 1:length(Data)
if Data{i,2} == -1
Data{i,2} = NaN
end
end
I do not get any error message. However, nothing gets replaced either. What am I missing or how can it be done more efficiently? Remember, I am just learning Matlab, so an easy solution would be cool :) Thank you!
Image Analyst on 29 Jan 2017
You should not use a cell array for this type of variable, where all the values in a single column are of the same type. You should use a table, which uses lots less memory and overhead than a cell array.

John Chilleri on 28 Jan 2017
Edited: John Chilleri on 29 Jan 2017
Hello,
Your code works for me, although I would recommend using
for i = 1:size(Data,1)
rather than
for i = 1:length(Data)
since Data is a 435x2, and you don't want to accidentally use the wrong dimension in the future.
As for your issue, the only thing that makes sense to me is that you've stored your numbers as strings rather than doubles, making the comparison do nothing.
Try,
for i = 1:length(Data)
if strcmp(Data{i,2},'-1')
Data{i,2} = NaN
end
end
If this works, then your -1's were strings rather than doubles.
Hope this helps!
John Chilleri on 29 Jan 2017
Edited: John Chilleri on 29 Jan 2017
I'll edit the above code - thank you for your input Jan, I hadn't considered that!

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