# Holoviews hover value error

Hi all,

I am writing a dynamic map to automatically change the resolution to be plot. But I find when I set `invert_yaxis=True`, data value displayed on the hover is wrong. Here is the example:

``````import math
import numpy as np
import holoviews as hv
from holoviews import streams
from functools import partial

class Coord(object):
def __init__(self,x0,dx,nx,y0,dy,ny):
self.x0 = x0
self.dx = dx
self.nx = nx
self.xm = x0+(nx-1)*dx
self.y0 = y0
self.dy = dy
self.ny = ny
self.ym = y0+(ny-1)*dy
self.maxlevel = math.floor(math.log2(min(nx,ny)))

def max_gix(self,level):
return math.ceil(self.nx/(2**level))-1, math.ceil(self.ny/(2**level))-1

def hv_bbox2gix_bbox(self,coord_bbox,level):
x0, y0, xm, ym = coord_bbox
xi0 = math.floor((x0-self.x0)/self.dx/2**level+0.5)
yi0 = math.floor((y0-self.x0)/self.dx/2**level+0.5)
xim = math.ceil((xm-self.x0)/self.dx/2**level-0.5)
yim = math.ceil((ym-self.x0)/self.dx/2**level-0.5)

xi_max, yi_max = self.max_gix(level)
return sorted((0,xi0,xi_max))[1], sorted((0,yi0,yi_max))[1], sorted((0,xim,xi_max))[1], sorted((0,yim,yi_max))[1]

def gix_bbox2hv_bbox(self,gix_bbox, level):
xi_max, yi_max = self.max_gix(level)
xi0, yi0, xim, yim = gix_bbox
xi0, yi0, xim, yim = sorted((0,xi0,xi_max))[1], sorted((0,yi0,yi_max))[1], sorted((0,xim,xi_max))[1], sorted((0,yim,yi_max))[1]
return (xi0-0.5)*2**level*self.dx+self.x0, (yi0-0.5)*2**level*self.dy+self.y0, (xim+0.5)*2**level*self.dx+self.x0, (yim+0.5)*2**level*self.dy+self.y0

def hv_image(x_range,y_range,width,height,scale,data,coord):
if x_range is None:
x0 = coord.x0; xm = coord.xm
else:
x0, xm = x_range
if y_range is None:
y0 = coord.y0; ym = coord.ym
else:
y0, ym = y_range
if height is None: height = hv.plotting.bokeh.ElementPlot.height
if width is None: width = hv.plotting.bokeh.ElementPlot.width

x_res = (xm-x0)/width; y_res = (ym-y0)/height
level = math.floor(math.log2(min(x_res,y_res)))
level = sorted((0, level, coord.maxlevel))[1]
xi0, yi0, xim, yim = coord.hv_bbox2gix_bbox((x0,y0,xm,ym),level)
coord_bbox = coord.gix_bbox2hv_bbox((xi0, yi0, xim, yim),level)
data_ = data[::2**level,::2**level][yi0:yim+1,xi0:xim+1]
return hv.Image(data_[::-1,:],bounds=coord_bbox)

def ras_plot(data:np.array,
bounds:tuple=None, # bounding box (x0, y0, x_max, y_max)
):
ny, nx = data.shape

if bounds is None:
x0 = 0; dx = 1; y0 = 0; dy = 1
else:
x0, y0, xm, ym = bounds
dx = (xm-x0)/(nx-1); dy = (ym-y0)/(ny-1)
coord = Coord(x0,dx,nx,y0,dy,ny)

rangexy = streams.RangeXY()
plotsize = streams.PlotSize()
images = hv.DynamicMap(partial(hv_image,data=data,coord=coord),streams=[rangexy,plotsize])
return images
``````
``````hv.extension('bokeh')

Y, X = (np.mgrid[0:100, 0:100]-50.)/20.

img = ras_plot(np.sin(X**2+Y**2))
img = img.redim(z=hv.Dimension('z',label='z',range=(-1,1)))

img.opts(hv.opts.Image(cmap='fire',width=600, height=400, colorbar=True,
tools=['hover',],
# invert_yaxis=True,
))
``````

With `invert_yaxis=True`:

With `invert_yaxis=False`:

Both of them generate the correct plot but the `z` value displayed on hover changes when I use the Pan tool for `invert_yaxis=True`.

Can you try to upgrade Bokeh to 3.4.1 (if you are not already on it)

Thanks a lot! @Hoxbro After I upgrade to Bokeh to 3.4.1, everything works well.