Same question posted on SO here: https://stackoverflow.com/q/55462861/8146556
In the sample Dash application below, I am attempting to create a dynamic layout with a variable number of rows and columns. This dynamic grid-style layout will be populated with various graphs that can be modified by dropdowns, etc.
The main issue I have run into thus far pertains to viewport-units and attempting to style the individual graphs appropriately to accommodate the dynamic layout. For example, I am modifying the style of the dcc.Graph() components via viewport-units, where the dimensions (e.g. height and width may be either 35vw or 23vw depending on the number of columns). When I change the number of columns from 3 to 2, for example, the height and width of the dcc.Graph() component are clearly changed, however this change is not reflected in the actual rendered layout until the window is physically resized (see the images below the sample code).
import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output, State
external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']
app = dash.Dash(__name__, external_stylesheets=external_stylesheets)
app.config.suppress_callback_exceptions = True
app.layout = html.Div([
html.Div(className='row', children=[
html.Div(className='two columns', style={'margin-top': '2%'}, children=[
html.Div(className='row', style={'margin-top': 30}, children=[
html.Div(className='six columns', children=[
html.H6('Rows'),
dcc.Dropdown(
id='rows',
options=[{
'label': i,
'value': i
} for i in [1,2,3,4]],
placeholder='Select number of rows...',
clearable=False,
value=2
),
]),
html.Div(className='six columns', children=[
html.H6('Columns'),
dcc.Dropdown(
id='columns',
options=[{
'label': i,
'value': i
} for i in [1,2,3]],
placeholder='Select number of columns...',
clearable=False,
value=3
),
])
]),
]),
html.Div(className='ten columns', id='layout-div', style={'border-style': 'solid', 'border-color': 'gray'}, children=[])
])
])
@app.callback(
Output('layout-div', 'children'),
[Input('rows', 'value'),
Input('columns', 'value')])
def configure_layout(rows, cols):
mapping = {1: 'twelve columns', 2: 'six columns', 3: 'four columns', 4: 'three columns'}
sizing = {1: '40vw', 2: '35vw', 3: '23vw'}
layout = [html.Div(className='row', children=[
html.Div(className=mapping[cols], children=[
dcc.Graph(
id='test{}'.format(i+1+j*cols),
config={'displayModeBar': False},
style={'width': sizing[cols], 'height': sizing[cols]}
),
]) for i in range(cols)
]) for j in range(rows)]
return layout
#Max layout is 3 X 4
for k in range(1,13):
@app.callback(
[Output('test{}'.format(k), 'figure'),
Output('test{}'.format(k), 'style')],
[Input('columns', 'value')])
def create_graph(cols):
sizing = {1: '40vw', 2: '35vw', 3: '23vw'}
style = {
'width': sizing[cols],
'height': sizing[cols],
}
fig = {'data': [], 'layout': {}}
return [fig, style]
if __name__ == '__main__':
app.server.run()
Relevant screenshots (Image 1 - page load, Image 2 - change columns to 2):
