Facet_row and facet_row labels when using imshow

📊 Plotly Python
1

An example to explain

import numpy as np
import plotly.express as px
fig = px.imshow(
    np.random.uniform(0, 1, size = (18, 28, 28)),
    facet_col = 0, facet_col_wrap = 6,
    binary_string = True,
    width=3200, height=1000)
fig.update_layout(yaxis = dict(showticklabels=False),
                  xaxis = dict(showticklabels=False))
for ann in fig.layout.annotations:
    ann.text = ''
fig.write_image('test.png')

The figure is supposed to show the evolution of three specimens over time. How can I get plotly to to set the axis labels like in the attached image? Also, how can I get plotly to remove the ugly vertical gap between rows?

mwe
mwe3200×1900 119 KB

2

Hi @bjourne ,

Welcome to the forum!

You can change the last six facet_col text annotations( which is the top row) to the values that you want. For y title (N=…) annotations, you can add another annotations using fig.add_annotation.

And for set manual vertical gap betweens rows, you need set your best distance by combining facel_row_spacing and height.

Here the code from your example.

import numpy as np
import plotly.express as px

xlabels = [0,20,40,60,80,100]
ylabels = [5,99,34]

col_wrap = 6
fig = px.imshow(
    np.random.uniform(0, 1, size = (18, 28, 28)),
    facet_col = 0, facet_col_wrap = col_wrap,
    facet_col_spacing=0,
    facet_row_spacing=0,
    binary_string = True,
    width=2000, height=1000)

fig.update_xaxes(showticklabels=False).update_yaxes(showticklabels=False)

# Change the facet_col only for 6 top rows
x_annotations = fig.layout.annotations
for idx,x_ann in enumerate(x_annotations):
	if idx >= len(x_annotations) - (len(xlabels) ):
		x_ann["text"] = '{}%'.format(xlabels[idx-len(x_annotations)])
		x_ann["font"] = {"color": "red"}
	else:
		x_ann["text"] = ""



# Add another 3 annotations for every rows
for idx, ylabel in enumerate(ylabels):
	y_ann = {
		'font': {'color':'red'},
	    'showarrow': False,
	    'text': 'N={}'.format(ylabel),
	    'x': 0.0,
	    'xanchor': 'right',
	    'xref': 'paper',
	    'y': 0.15 + (idx*0.35) ,
	    'yanchor': 'middle',
	    'yref': 'paper'}
	fig.add_annotation(y_ann)
	
# fig.show()
fig.write_image('test.png')

image
image1501×715 42.9 KB

Hope this help.

1 Like
3

Hi @farispriadi and thanks for the kind welcoming. Your code works except for the spacing between the images which I can’t seem to get right. It is as if the labels are there, just not visible.

1 Like