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# changing the axis of a plot in a way that the data series starts at x=0 at a point at one point on the y-axis and ends on the right end of the plot

Asked by Locks on 29 Apr 2013

hi,

I have this code:

```dates=datenum(VIXdate)
```
```y=VIX
```
```plot(dates,y)
```
```%datevc divides the date in different columns, first colum is the year,
%second the month and thrid the day
d=datevec(dates)
```
```%Takes just the year (first column)
d=d(:,1)
```
```%takes every year just once
[a,idx]=unique(d(:,1),'first')
```
```ylabel('VIX');
```
```set(gca,'xtick',dates(idx),'xticklabel',a)
```
```set(gca,'Box','off')
```

this works fine, but the problem I faces is that the time series (y=VIX) does not start at the left end of the plot but instead there is a space between the y-axis and the first point of the time series. I know that when there are normal values on the x-axis, I can change it, but I am not able to do it with dates, what do I need to do?

## 1 Comment

Babak on 29 Apr 2013

Undefined function or variable 'VIXdate'.

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Answer by Jonathan Epperl on 2 May 2013

This is still not a working example, the variable VIXdate is obviously unknown to us...

So the dirty way again:

```ytix = get(gca,'YTick');
set(gca,'YTick',ytix(2:end));
```

Locks on 2 May 2013

perfect, thanks

I have another similar problem with this code here:

```dates=datenum(dataSet(:,1));
```
```%SPX
SPX=dataSet(:,2);
```
```%VIX
VIX=dataSet(:,3);
```
```plotyy(dates,SPX,dates,VIX);
```
```d=datevec(dates);
d=d(:,1);
```
```[a,idx]=unique(d(:,1),'first');
```
```ylabel('S&P 500 Index')
%axis([ 0 2000]);
set(gca,'xtick',dates(idx),'xticklabel',a)
set(gca,'Box','off')
```

here it shows me on the xaxis both the date as well as the date in numerical form, how can I change that?

Also I would like to change the color from both y axis into black, is that possible?

Jonathan Epperl on 2 May 2013

You should make that a new question, and finally make it so that we can copy and paste your code into our matlab and run it and see what it is you want to achieve.

Locks on 2 May 2013

ok, I did so, it's fine now, thanks

Answer by Mel on 1 May 2013

You could also set just the x axis to be the same as your data:

```xlim([0 max(dates)])
```

Answer by Jonathan Epperl on 29 Apr 2013
```axis tight
```

Locks on 1 May 2013

that is working, but I am only looking for that for the x axis but not for the y axis, is that also possible?

Jonathan Epperl on 1 May 2013

Sure. Without knowing what your actual data looks like (it would still be nice if you could post a working minimal example), you could do that:

```ylims = get(gca,'YLim');
axis tight
set(gca,'YLim',ylims);
```

Dirty, but should work.

Locks on 1 May 2013
```    dates=datenum(VIXdate)
y=VIX
plot(dates,y)```
`    d=datevec(dates)`
```    %Takes just the year (first column)
d=d(:,1)```
```    %takes every year just once
[a,idx]=unique(d(:,1),'first')```
`    ylabel('VIX');`
`    set(gca,'xtick',dates(idx),'xticklabel',a)`
```    ylims = get(gca,'YLim');
axis tight
set(gca,'YLim',ylims);```
`    set(gca,'Box','off')`

it's working perfectly now, thanks!

in addition, it would be great if the number 0 on the y axis is not shown in the plot due to the fact that it's so near to the numbers on the x axis, is there a way to do that?