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# change scales from the x axis

Asked by Locks on 2 May 2013

Hi,

I intend to do a chart with two yaxis, the code is the following:

```dates=datenum(dataSet(:,1));
```
```%SPX
SPX=dataSet(:,2);
```
```%VIX
VIX=dataSet(:,3);
```
```plotyy(dates,SPX,dates,VIX);
```
```%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)
ytix = get(gca,'YTick');
set(gca,'YTick',ytix(2:end));
```

This is working but unfortunately besides the years I have also the numeric date displayed on the x axis, how can I change that?

is there a way to make both y axis black instead of blue and green?

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Answer by Azzi Abdelmalek on 2 May 2013

use

```[ax,h1,h2]=plotyy(dates,SPX,dates,VIX);
set(ax(1),'ycolor','k')
set(ax(2),'ycolor','k')
```

Locks on 2 May 2013

perfect, thanks!!

Have you also a solution that there are no spaces between the plot and the y axis, in other words the plot should start at the left yaxis and ends at the richt yaxis

Azzi Abdelmalek on 2 May 2013
```set(ax,'xlim',[min(x) max(x)])
```
Locks on 2 May 2013

perfect, thanks