import numpy as np
import os
import csv

RoadName = ['A','B','C','D','E','F','G']

if not os.path.isfile(r'RoadSpeed.csv'):
    with open('RoadSpeed.csv','a',newline='',encoding='utf-8') as csvfile:
        fieldnames = ['RoadName','Time','Speed']
        writer = csv.DictWriter(csvfile,fieldnames=fieldnames)
        writer.writeheader()
        for road in RoadName:
            for h in range(24):
                for m in range(60):
                    data = {}
                    data['RoadName'] = road
                    data['Time'] = '20210924{:0>2}{:0>2}'.format(h,m)
                    data['Speed'] = str(np.random.uniform(40,120,1)).strip('[]')
                    writer.writerow(data)

import pandas as pd
import seaborn as sns

help(pd.pivot_table)
help(sns.heatmap)

data = pd.pivot_table(df,index = ['RoadName'],columns = ['Time'],values = ['Speed']).reset_index(drop=False)

ax = sns.heatmap(data, cmap=plt.cm.RdYlGn,xticklabels=1, yticklabels=1)

import seaborn as sns
import pandas as pd
import matplotlib.pyplot as plt
import numpy as np

df = pd.read_csv(r'RoadSpeed.csv',encoding='utf-8')

#設置中文和負號正常顯示
plt.rcParams['font.sans-serif'] = 'SimHei'
plt.rcParams['axes.unicode_minus'] = False
plt.rcParams['font.sans-serif'] = ['SimHei']  # 用來正常顯示中文標簽
#提高圖像清晰度
plt.rcParams['savefig.dpi'] = 400
plt.rcParams['figure.dpi'] = 400

#pivot_table
data = pd.pivot_table(df,index = ['RoadName'],columns = ['Time'],values = ['Speed'])
data.columns = data.columns.get_level_values(1).values
data.sort_index(ascending = True)

#heatmap
plt.figure(figsize=(36, 24))
ax = sns.heatmap(data, cmap=plt.cm.RdYlGn,xticklabels=1, yticklabels=1)

#減少坐標軸密度
times = list(data.columns)
ticks = list(range(0,len(times),15)) # 每隔15min顯示一次
if ticks[-1] != len(times)-1:
    ticks.append(len(times)-1)
labels=[times[i] for i in ticks]

#設置刻度、標簽等
ax.set(xlim=[0,len(times)-1])
ax.set_xticks(ticks)
ax.set_xticklabels(labels,rotation=90,horizontalalignment = 'right',weight = 'bold')
ax.set_xlabel("時間", fontsize=30, color="k") #x軸label的文本和字體大小
ax.set_ylabel("路段", fontsize=30, color="k") #y軸label的文本和字體大小
plt.xticks(fontsize=20,weight = 'bold')  # x軸刻度的字體大小
plt.yticks(fontsize=20,weight = 'bold',rotation = 30)  # y軸刻度的字體大小
ax.set_title("各路段時變車速" ,fontsize=50) #圖片標題文本和字體大小
cax = plt.gcf().axes[-1] 
cax.tick_params(labelsize=60)
plt.savefig('各路段時變車速.png')

'''
    設置圖例只顯示1,2,3,4四個數字
    并用暢通、輕度擁擠、中度擁擠、重度擁擠來代替
'''  
c_bar = ax.collections[0].colorbar
c_bar.set_ticks([4,3,2,1])
c_bar.set_ticklabels(['暢通', '輕度擁堵', '中度擁堵','重度擁堵'])