Changing grid position in Bokeh - bokeh

Question

I'm trying to make a table to represent the relationship between categorical values based on their count. This is my current code:
source = ColumnDataSource(df)
mapper = LinearColorMapper(palette=brewer['YlGnBu'][4], low=df['count'].min(), high=df['count'].max())
tooltips = [
("Resource", "#org:resoure"),
("Activity", "#concept:name"),
("Count", "#count"),
]
p = figure(plot_width=df['org:resource'].nunique()*180, plot_height=df['concept:name'].nunique()*100, title="US Unemployment 1948—2016",
y_range=df['concept:name'].unique(), x_range=df['org:resource'].unique(),x_axis_location="above", tooltips=tooltips)
p.rect(y="concept:name", x="org:resource", width=1, height=1, source=source,
line_color=None, fill_color=transform('count', mapper))
color_bar = ColorBar(color_mapper=mapper, location=(0, 0),
ticker=BasicTicker(),
formatter=PrintfTickFormatter(format="%d%%"))
p.add_layout(color_bar, 'right')
p.axis.axis_line_color = None
p.axis.major_tick_line_color = None
p.axis.major_label_text_font_size = "13px"
p.axis.major_label_standoff = 0
p.xaxis.major_label_orientation = 0
output_notebook()
show(p)
However, this code produces a grid that does not suite categorical values. How can I shift the grid down?
current visual produced by code

Answer 1

You can achieve this using a FixedTicker.
Here is a very basic example where p.rect() is used.
old
new
The code is very similar, except the ticks are shifted by 0.5 on both axis in the new version using the FixedTicker I mentioned.
old
from bokeh.plotting import figure, output_file, show
data = [1, 5]
plot = figure(plot_width=300, plot_height=300)
plot.rect(x=data, y=data, width=1, height=1, color="#CAB2D6")
show(plot)
new
from bokeh.plotting import figure, output_file, show
from bokeh.models import FixedTicker
data = [1, 5]
plot = figure(plot_width=300, plot_height=300)
plot.rect(x=data, y=data, width=1, height=1, color="#CAB2D6")
_max = max(data)
plot.xaxis.ticker = FixedTicker(ticks=[x+0.5 for x in range(_max+1)])
plot.yaxis.ticker = FixedTicker(ticks=[x+0.5 for x in range(_max+1)])
show(plot)