# How do we plot a graph with non available values for y without breaking the continuity?

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Emerson De Souza on 25 Oct 2012
Commented: Grant on 11 Apr 2017
INTRO: I have an array M as below:
M=
1 4
2 NaN
3 10
4 NaN
5 NaN
6 15
7 NaN
8 17
9 59
10 NaN
GOAL: I want to plot the second versus the first column as follow:
h=plot(M(:,1),M(:,2));
PROBLEM: Due to the NaN, it does not plot the gaps correctly and breaks the continuity of the graph.
I wonder if someone could suggest me to some command lines that could fix this issue.
I thank you in advance for your help
Emerson

Matt Tearle on 25 Oct 2012
You can interpolate to fill the missing values, as Azzi suggests, or simply remove all the NaNs:
idx = ~isnan(M(:,2));
x = M(idx,1);
y = M(idx,2);
plot(x,y,'o-')
If you don't plot markers on the data points, this will look exactly the same as Azzi's solution using interpolation. The difference is whether or not you care about showing which points are actual data values.
##### 1 CommentShowHide None
Grant on 11 Apr 2017
My problem is that I do care about what is a real value. I want to do what is easy in Excel - have a marker at each real value in my lineplot and have the lines interpolate between points

### More Answers (1)

Azzi Abdelmalek on 25 Oct 2012
Edited: Azzi Abdelmalek on 25 Oct 2012
Use interpolation
x=M(:,1);
y=M(:,2);
idx=find(~isnan(y))
y=interp1(x(idx),y(idx),x,'linear')
or remove rows containing nan
x=M(:,1);
y=M(:,2);
x(find(isnan(y)))=[]
y(find(isnan(y)))=[]
##### 2 CommentsShowHide 1 older comment
Azzi Abdelmalek on 25 Oct 2012
I agree

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