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

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:

M=load('M.txt');
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

Answer 1

[Matt Tearle]

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.

[Grant]

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

Answer 2

[Azzi Abdelmalek]

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)))=[]

[Matt Tearle]

idx = ~isnan(y);

No need for the find. (Sorry, I love logical indexing!)

[Azzi Abdelmalek]

I agree