Hi,
ImageItem is a descendent of Qt QGraphicsItem
<https://doc.qt.io/qt-5/qgraphicsobject-members.html>, so the real work
happens down there somewhere. Here's a an example of how I do what you
describe:
# x, y are arrays of x and y axis labels, assumes regularly spaced grid
# imageItem has been added to the plotItem
x_scale = (self.x[-1] - self.x[0])/(self.x.shape[0]-1) if self.x.shape[0] >
1 else 1.0
y_scale = (self.y[-1] - self.y[0])/(self.y.shape[0]-1) if self.y.shape[0] >
1 else 1.0
self.plotItem.setLimits(xMin=self.x[0] - x_scale/2, xMax=self.x[-1] +
x_scale/2,
yMin=self.y[0] - y_scale/2, yMax=self.y[-1] +
y_scale/2)
self.imageItem.resetTransform()
self.imageItem.scale(x_scale, y_scale)
self.imageItem.setPos(self.x[0] - x_scale/2, self.y[0] - y_scale/2)
Patrick
On Friday, 24 May 2019 23:56:59 UTC+9:30, alxcpa 01101 wrote:
>
> I'm having trouble getting positive and negative Y values for a
> spectrogram. I can use img.scale(dt,df) to scale properly but I would
> actually like to scale and shift down by the half of the max frequency,
> like img.scale(dt, df (then - fmax/2)). I can't seem to find the source
> for .scale() or .setPos(), in ImageView it references the functions to
> ImageItem, but it is not in the ImageItem source. My only other idea is to
> create 2 images and scale one positive and one negative and combine them,
> but this doesn't seem necessary. Any ideas?
>
--
You received this message because you are subscribed to the Google Groups
"pyqtgraph" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/pyqtgraph/0af1617f-247e-4ba4-a56c-b079c5faee5a%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
