seaborn可以說是matplotlib的升級版,使用seaborn繪製折線圖時參數數據可以傳遞ndarray或者pandas,方便又好看!本篇用繪製強化學習中的rewards舉例,實際上也可以用來機器學習中的loss曲線,原理類似。
從一個簡單示例開始
import matplotlib.pyplot as plt
import numpy as np
import seaborn as sns # 導入模塊
sns.set() # 設置美化參數,一般默認就好
rewards = np.array([0, 0.1,0,0.2,0.4,0.5,0.6,0.9,0.9,0.9])
plt.plot(rewards)
plt.show()
如上首先導入seaborn模塊,並設置美化參數(aesthetic parameters)sns.set()
,使用matplotlib.pyplot as plt
就可以繪製一個基本的圖像:
使用sns.lineplot或者sns.relplot
實際上relplot包含lineplot和scatterplot,並通過kind
傳參可以轉換爲lineplot,
relplot(kind="line")等價於lineplot
relplot(kind="scatter")等價於scatterplot
然後再進行適當的調整並加上x,y軸的label,如下:
import matplotlib.pyplot as plt
import numpy as np
import seaborn as sns; sns.set() # 因爲sns.set()一般不用改,可以在導入模塊時順便設置好
rewards = np.array([0, 0.1,0,0.2,0.4,0.5,0.6,0.9,0.9,0.9])
sns.lineplot(x=range(len(rewards)),y=rewards)
# sns.relplot(x=range(len(rewards)),y=rewards,kind="line") # 與上面一行等價
plt.xlabel("episode")
plt.ylabel("reward")
plt.show()
最後呈現效果如下:
繪製rewards聚合圖
當我們對同一實驗作出多次得到一組rewards時,如下:
rewards1 = np.array([0, 0.1,0,0.2,0.4,0.5,0.6,0.9,0.9,0.9])
rewards2 = np.array([0, 0,0.1,0.4,0.5,0.5,0.55,0.8,0.9,1])
rewards=np.vstack((rewards1,rewards2)) # 合併成二維數組
我們希望繪製出聚合圖,但是sns.lineplot
無法輸入一維以上的數據,我們可以將它們全部轉爲一維,雖然有些難看:
import matplotlib.pyplot as plt
import numpy as np
import seaborn as sns; sns.set() # 因爲sns.set()一般不用改,可以在導入模塊時順便設置好
rewards1 = np.array([0, 0.1,0,0.2,0.4,0.5,0.6,0.9,0.9,0.9])
rewards2 = np.array([0, 0,0.1,0.4,0.5,0.5,0.55,0.8,0.9,1])
rewards=np.concatenate((rewards1,rewards2)) # 合併數組
episode1=range(len(rewards1))
episode2=range(len(rewards2))
episode=np.concatenate((episode1,episode2))
sns.lineplot(x=episode,y=rewards)
plt.xlabel("episode")
plt.ylabel("reward")
plt.show()
結果如圖:
繪製出了帶聚合陰影的圖,實際上實際部分是seaborn默認對同一x軸的多個y值即rewards做了均值,陰影部分表示多組rewards的範圍,可以使用sns.lineplot(x=episode,y=rewards,ci=None)
去掉。
使用pandas傳參
上面都是用ndarray傳參,這樣一方面免不了與matplotlib.pyplot
混雜的成分比如plt.xlabel,另外繪製rewards聚合圖,也比較麻煩。既然使用pandas傳參,就需要先把array轉成DataFrame形式,如下:
import numpy as np
import pandas as pd
rewards1 = np.array([0, 0.1,0,0.2,0.4,0.5,0.6,0.9,0.9,0.9])
rewards2 = np.array([0, 0,0.1,0.4,0.5,0.5,0.55,0.8,0.9,1])
rewards=np.vstack((rewards1,rewards2)) # 合併數組
df = pd.DataFrame(rewards).melt(var_name='episode',value_name='reward') # 推薦這種轉換方法
print(df)
推薦上述轉化方法,這樣無論rewards
多少維都不影響最終的繪圖方式,其中melt
方法將所有維合併成一列,var_name='episode',value_name='reward'
則更改對應的列名,轉化結果如下:
episode reward
0 0 0.0
1 0 0.1
2 0 0.0
3 0 0.2
4 0 0.4
5 0 0.5
6 0 0.6
7 0 0.9
8 0 0.9
9 0 0.9
下面完整繪圖:
import seaborn as sns;sns.set()
import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
import pandas as pd
rewards1 = np.array([0, 0.1,0,0.2,0.4,0.5,0.6,0.9,0.9,0.9])
rewards2 = np.array([0, 0,0.1,0.4,0.5,0.5,0.55,0.8,0.9,1])
rewards=np.vstack((rewards1,rewards2)) # 合併數組
df = pd.DataFrame(rewards).melt(var_name='episode',value_name='reward')
sns.lineplot(x="episode", y="reward", data=df)
plt.show()
注意這裏的x,y不再傳入數組,而是傳入DataFrame中對應的列名,類似於python字典中的鍵,結果如下:
牛刀小試
最後繪製一個更爲複雜的可以用於paper的繪製方法:
import seaborn as sns; sns.set()
import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
def get_data():
'''獲取數據
'''
basecond = np.array([[18, 20, 19, 18, 13, 4, 1],[20, 17, 12, 9, 3, 0, 0],[20, 20, 20, 12, 5, 3, 0]])
cond1 = np.array([[18, 19, 18, 19, 20, 15, 14],[19, 20, 18, 16, 20, 15, 9],[19, 20, 20, 20, 17, 10, 0]])
cond2 = np.array([[20, 20, 20, 20, 19, 17, 4],[20, 20, 20, 20, 20, 19, 7],[19, 20, 20, 19, 19, 15, 2]])
cond3 = np.array([[20, 20, 20, 20, 19, 17, 12],[18, 20, 19, 18, 13, 4, 1], [20, 19, 18, 17, 13, 2, 0]])
return basecond, cond1, cond2, cond3
data = get_data()
label = ['algo1', 'algo2', 'algo3', 'algo4']
df=[]
for i in range(len(data)):
df.append(pd.DataFrame(data[i]).melt(var_name='episode',value_name='loss'))
df[i]['algo']= label[i]
df=pd.concat(df) # 合併
sns.lineplot(x="episode", y="loss", hue="algo", style="algo",data=df)
plt.title("some loss")
plt.show()
結果如下:
覺得還可以的話,不妨給個贊XD。