如何在破折号Web应用程序上显示wordcloud图像 [英] how to show wordcloud image on dash web application

问题描述

我需要在我的破折号应用程序上渲染wordcloud.根据此线程 https://community.plot.ly/t/solved-is-it-possible-to-make-a-wordcloud-in-dash/4565 ，破折号中没有wordcloud内置组件.一种解决方法是使用WordCloud模块将wordcloud生成为图像，并使用dash_html_components.Img在布局上显示.

I need to render a wordcloud on my dash application. According to this thread https://community.plot.ly/t/solved-is-it-possible-to-make-a-wordcloud-in-dash/4565, there is no wordcloud build-in component in dash. One workaround is to use WordCloud module to produce the wordcloud as image and use dash_html_components.Img to show on layout.

我是Dash的新手.不知道如何渲染图像.每次生成wordcloud时都需要将wordcloud保存为临时图像吗?

I'm new to Dash. Not sure how I can render the image. Do I need to save wordcloud as temp image everytime I produce a wordcloud?

非常感谢Dash方面的专业人士可以提供帮助.

Really appreciate it if anyone with some expertise in Dash can help with that.

代码如下:

import dash
import dash_core_components as dcc
import dash_html_components as html

print(dcc.__version__) # 0.6.0 or above is required

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = dash.Dash(__name__, external_stylesheets=external_stylesheets)

dfm = pd.DataFrame({'word': ['apple', 'pear', 'orange'], 'freq': [1,3,9]})

app.layout = html.Div([
    html.Img(id = 'image_wc')
])

# function to make wordcoud from word frequency dataframe
def plot_wordcloud (data):
        d = {}
        for a, x in data.values:
            d[a] = x
        wc = WordCloud(background_color='black',
                    width=1800,
                    height=1400).generate_from_frequencies(frequencies=d)   
        return (wc)

@app.callback(dash.dependencies.Output('image_wc', 'img'))
def make_image ():
    img = plot_wordcloud (data = dfm)
    return (img)


if __name__ == '__main__':
    app.run_server(debug=True)

推荐答案

下面是一个有效的示例.它使用pip -installable wordcloud库，并通过BytesIO传递结果图像的base-64编码的PNG表示形式，因此您不必每次都转储所有创建的PNG文件.

Here's a working example below. It uses the pip-installable wordcloud library, and passes a base-64 encoded PNG representation of the resulting image through BytesIO so you don't need to dump all the created PNG files each time.

我已经触发它了，以便它可以在加载Dash应用程序时运行，尽管您可以使它在按钮或类似按钮的作用下动态地工作.

I've got it triggering off of itself so that it'll run when you load the Dash app, though you could have it work dynamically off of a button or similar.

import dash
import dash.dependencies as dd
import dash_core_components as dcc
import dash_html_components as html

from io import BytesIO

import pandas as pd
from wordcloud import WordCloud
import base64

# external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = dash.Dash(__name__) #, external_stylesheets=external_stylesheets)

dfm = pd.DataFrame({'word': ['apple', 'pear', 'orange'], 'freq': [1,3,9]})

app.layout = html.Div([
    html.Img(id="image_wc"),
])

def plot_wordcloud(data):
    d = {a: x for a, x in data.values}
    wc = WordCloud(background_color='black', width=480, height=360)
    wc.fit_words(d)
    return wc.to_image()

@app.callback(dd.Output('image_wc', 'src'), [dd.Input('image_wc', 'id')])
def make_image(b):
    img = BytesIO()
    plot_wordcloud(data=dfm).save(img, format='PNG')
    return 'data:image/png;base64,{}'.format(base64.b64encode(img.getvalue()).decode())

if __name__ == '__main__':
    app.run_server(debug=True)

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