如何修复：TypeError: no numeric data to plot

在这篇文章中，我们将修复这个错误。TypeError: no numeric data to plot.

这种错误发生的情况：

# importing pandas
import pandas as pd
# importing numpy
import numpy as np
import matplotlib.pyplot as plt
  
petal_length = ['3.3', '3.5', '4.0', '4.5',
                '4.6', '5.0', '5.5', '6.0', 
                '6.5', '7.0']
petal_width = ['3.6', '3.8', '4.4', '6.6',
               '6.8', '7.0', '7.5', '8.0', 
               '8.5', '8.9']
  
  
df = pd.DataFrame({'petal_length(cm)': petal_length,
                   'petal_width(cm)': petal_width})
df.plot(x='petal_length(cm)', y='petal_width(cm)')
plt.show()

输出:

TypeError: no numeric data to plot

错误原因：

绘图只能在数字数据上进行，当我们绘制的数据类型不同于数字数据时，就会出现这个错误。要知道数据类型是否为数字，我们可以通过使用函数dtypes()来知道。

print(df.dtypes)

我们用来绘制的数据必须是数字的。

修复错误

这个错误可以通过将要绘制的数据转换为数字数据来解决。为了将数据转换为数字数据，我们可以使用函数 astype() 或 to_numeric()。

方法1：使用 astype() 函数

语法:

df['column_name']= df['column_name'].astype(data_type)

其中，df是输入数据帧

示例:

# importing pandas
import pandas as pd
# importing numpy
import numpy as np
# importing matplotlib.pyplot
import matplotlib.pyplot as plt
  
petal_length = ['3.3', '3.5', '4.0', '4.5',
                '4.6', '5.0', '5.5', '6.0', 
                '6.5', '7.0']
petal_width = ['3.6', '3.8', '4.4', '6.6',
               '6.8', '7.0', '7.5', '8.0',
               '8.5', '8.9']
  
  
df = pd.DataFrame({'petal_length(cm)': petal_length,
                   'petal_width(cm)': petal_width})
df['petal_length(cm)'] = df['petal_length(cm)'].astype(float)
df['petal_width(cm)'] = df['petal_width(cm)'].astype(float)
  
df.plot(x='petal_length(cm)', y='petal_width(cm)')
plt.show()

输出 :

方法2 :使用to_numeric()函数

语法:

df['column_name'] = pd.to_numeric(df['column_name'])

其中df是输入数据帧

示例 :

# importing pandas
import pandas as pd
# importing numpy
import numpy as np
# importing matplotlib.pyplot
import matplotlib.pyplot as plt
  
petal_length = ['3.3', '3.5', '4.0', '4.5',
                '4.6', '5.0', '5.5', '6.0',
                '6.5', '7.0']
petal_width = ['3.6', '3.8', '4.4', '6.6',
               '6.8', '7.0', '7.5', '8.0', 
               '8.5', '8.9']
  
  
df = pd.DataFrame({'petal_length(cm)': petal_length,
                   'petal_width(cm)': petal_width})
# Using to_numeric() function
df['petal_length(cm)'] = pd.to_numeric(df['petal_length(cm)'])
df['petal_width(cm)'] = pd.to_numeric(df['petal_width(cm)'])
  
df.plot(x='petal_length(cm)', y='petal_width(cm)')
plt.show()

输出: