matplotlib生成图像至flask

• matlot.json

{
  "上海": 15260,
  "杭州": 12586,
  "北京": 13305,
  "天津": 9000,
  "深圳": 16060,
  "广州": 14010,
  "西安": 8000,
  "重庆": 7800,
  "成都": 8500
}

• func.py

import json


def json_to_dict(filename):
    json_file = open(filename, 'r', encoding='utf-8')
    return json.loads(json_file.read())

• views.py

from . import matlot
from matplotlib.pylab import *
from flask import render_template
from io import BytesIO
from .func import json_to_dict, ax
import base64

def json_img(data):
    font = {'family': 'SimHei',
            'weight': 'bold',
            'size': '14'}
    rc('font', **font)  # 设置支持中文
    rc('axes', unicode_minus=False)
    rcParams['savefig.dpi'] = 100  # 设置像素大小

    for x, y in data.items():
        bar(x, y, align='center')   # 生成柱状图
        text(x, y + 100, '%.2f' % y, ha='center', va='bottom', size=10, color="#909299") # 柱状添加标签数据

    # 写入内存，py3 BytesIO()
    img = BytesIO()
    savefig(img, format='png')
    img.seek(0)
    # img转义base64编码
    img_base64 = base64.b64encode(img.getvalue()).decode('utf8')

    # 边框，边框坐标处理
    ax = gca()
    ax.spines['right'].set_color('none') # 隐藏右边框线
    ax.spines['top'].set_color('none') # 隐藏上边框线
    ax.xaxis.set_ticks_position('bottom')
    ax.spines['bottom'].set_position(('data',0)) # 定位下边框线0位置
    
    return img_base64


@matlot.route('/')
def fig():
    data = json_to_dict('./file/matlot.json')
    # print(data)
    # return send_file(json_img(data), mimetype='image/png')
    return render_template('fig.html',img_base64=json_img(data))