# How can I set an axis outside the polar figure like this photo?

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Hengkai Wu on 18 Apr 2020
Commented: Tommy on 23 Aug 2020 Hello friends,
I want to add a scalebar of my r-axis and label it like the figure I show (with red ring), but it seem not easy to move the exsisting axis, what should I do?
Can anyone help me? I really appreciate it.

Tommy on 18 Apr 2020
Edited: Tommy on 18 Apr 2020
You could create Cartesian axes which overlie the polar axes and are invisible except for the y axis, whose ticks are set to match the r axis ticks:
pa = polaraxes('Position', [0.25 0.25 0.6 0.6]);
polarplot(pa, randi(10,10,1),'o');
pa.RTickLabel = [];
a = axes('Color', 'none',...
'XColor', 'none',...
'Position', pa.Position,...
'YLim', [-pa.RLim(2) pa.RLim(2)],...
'YTick', unique([-flip(pa.RTick) pa.RTick]));
ylabel(a, 'r axis label') Hengkai Wu on 20 Apr 2020

zein on 22 Aug 2020
Edited: zein on 22 Aug 2020
how can i modify the rlabel to be starting from 70 instread of zero as i have used the same code but for my case i want the scale to start from 70 instead of zero as shown in the following figure I have used the same code line but the output rlabel started from zero what should i modify in the code to set the rlabel from (70-120)
figure(2)
set(gcf,'color','w');
ax = polaraxes('Position', [0.25 0.25 0.6 0.6])
polarplot (theta,splbn(21,:));
ax.ThetaZeroLocation = 'left';
rlim([70,120])
ax.RTickLabel = [];
ticks = [-flip(ax.RTick(2:end)) ax.RTick];
a = axes('Color', 'none',...
'XColor', 'none',...
'Position', ax.Position,...
'YLim', [-ax.RLim(2) ax.RLim(2)],...
'YTick', ticks,...
'YTickLabel', abs(ticks));
ylabel(a, 'r axis label')
Tommy on 23 Aug 2020
Hello, try this:
figure(2)
set(gcf,'color','w');
ax = polaraxes('Position', [0.25 0.25 0.6 0.6]);
polarplot (theta,splbn(21,:));
ax.ThetaZeroLocation = 'left';
ax.RTickLabel = [];
% grab the tick locations before changing the r limits, because the
% tick locations should be centered around 0:
ticklocs = [-flip(ax.RTick(2:end)) ax.RTick];
rlim(ax, [70,120])
ticks = [-flip(ax.RTick(2:end)) ax.RTick];
a = axes('Color', 'none',...
'XColor', 'none',...
'Position', ax.Position,...
'YLim', [min(ticklocs), max(ticklocs)],...
'YTick', ticklocs,... use the tick locations to place the ticks
'YTickLabel', abs(ticks));
ylabel(a, 'r axis label')
Hopefully this works for you