刻度的半径：

你可以使用dims()函数来获得相较于ideogram的位置：

radius= dims(ideogram,radius_outer) #取到ideogram的外半径

当然你也可以在此基础上进行改变

radius= dims(ideogram,radius_outer) + 25p radius= dims(image,radius) - 25p

你可以为ticks设置几个半径，这样就会显示多组ticks

刻度的朝向

orientation = out #你可以选择是in或者是out

刻度的单位：

还记得我们一开始有设定过染色体的单位么？

chromosomes_units=1000000(1Mb)
label_multiplier = 1e-6 这表示对于染色体上实际距离为1Mb的区间，我们的label会计算为1，同理染色体上为10Mb的距离，就会被表示成10

标签的间隔

<ticks>

  radius               = dims(ideogram,radius_outer)
  multiplier           = 1e-6

  <tick>
  spacing = 10u
  ... parameters for ticks every 10u (=10Mb)...
  </tick>

  <tick>
  spacing = 5u
  ... parameters for ticks every 5u (=5Mb)...
  </tick>

  <tick>
  spacing = 1u
  ... parameters for ticks every 1u (=1Mb)...
  </tick>

</ticks>

• 标签间隔是以unit来表示的。注意ticks的绘制顺序是从上到下，但是已经被绘制过的刻度就不会再被绘制了。
• 有间断的ideogram区域是不会被绘制的
• 过多的标签会严重影响绘制速度，所以大家一定要设计好 chromosomes_units label_multiplier spacing的值

刻度的基本参数

• spacing - the distance between the ticks in this set and should be expressed in units of - chromosomes_units (u) or bases (b). chromosomes - optional list of ideograms on which ticks are drawn or are suppressed
• size - the length of the tick line, in pixels (p) or relative (r) to thickness of ideogram
• thickness - the thickness of the tick line, in pixels (p) or relative (r) to the size of the tick
• color - the color of the tick line and its label
• show_label - toggles display of the tick's associated label and is functional only if show_tick_labels is set
• label_size - controls the size of the tick's label in pixels (p) or relative (r) to the size of the tick
• label_offset - additional padding between the label and end of the tick mark, in pixels (p) or relative (r) to the size of the tick
• format - a printf style format applied to the label of the tick (e.g. %d for integer, %.nf for n-decimal float).