在 Pandas Dataframe 中突出显示负值红色和黑色正值

让我们看看在 Pandas Dataframe 中突出显示正值红色和黑色负值的各种方法。
首先，让我们制作一个数据框：

Python3

# Import Required Libraries
import pandas as pd
import numpy as np
  
  
# Create a dictionary for the dataframe
dict = {
  'Name': ['Sukritin', 'Sumit Tyagi', 
           'Akriti Goel', 'Sanskriti',
           'Abhishek Jain'],
   'Age': [22, 20, 45, 21, 22],
  'Marks': [90, 84, -33, -87, 82]
}
  
# Converting Dictionary to
# Pandas Dataframe
df = pd.DataFrame(dict)
  
# Print Dataframe
print(df)

Python3

# Define a function for colouring 
# negative values red and 
# positive values black
def highlight_max(s):
    if s.dtype == np.object:
        is_neg = [False for _ in range(s.shape[0])]
    else:
        is_neg = s < 0
    return ['color: red;' if cell else 'color:black' 
            for cell in is_neg]
  
# Using apply method of style 
# attribute of Pandas DataFrame
df.style.apply(highlight_max)

Python3

# Define a function which 
# returns the list for 
# df.style.apply() method
def highlight_max(s):
    if s.dtype == np.object:
        is_neg = [False for _ in range(s.shape[0])]
    else:
        is_neg = s < 0
    return ['background: red; color:white' 
            if cell else 'background:black; color:white' 
            for cell in is_neg]
  
# Using apply method of style 
# attribute of Pandas DataFrame
df.style.apply(highlight_max)

Python3

# Define a function for 
# colouring negative values 
# red and positive values black
def highlight_max(cell):
    if type(cell) != str and cell < 0 :
        return 'color: red'
    else:
        return 'color: black'
  
df.style.applymap(highlight_max)

Python3

# Define a function which 
# returns string for 
# applymap() method
def highlight_max(cell):
    if type(cell) != str and cell < 0 :
        return 'background: red; color:black'
    else:
        return 'background: black; color: white'
  
df.style.applymap(highlight_max)

输出：

现在，来到突出显示部分。我们的目标是突出显示红色的负值和黑色的正值。

方法 1：使用Dataframe.style.apply() 。

Syntax: DataFrame.style.apply(self, func, axis=0, subset=None, **kwargs)
Parameters:

func: It should take a pandas.Series or pandas.DataFrame based on the axis and should return an object with the same shape.
axis: {0 or ‘index’, 1 or ‘columns’, None}, default 0. Apply to each column (axis=0 or ‘index’), to each row (axis=1 or ‘columns’), or to the entire DataFrame at once with axis=None.
subset: Set of columns or rows on which you want to call the func.
**kwargs: Pass along to func.

Returns: Styler object.

编程需要懂一点英语

示例 1：突出显示文本。

Python3

# Define a function for colouring 
# negative values red and 
# positive values black
def highlight_max(s):
    if s.dtype == np.object:
        is_neg = [False for _ in range(s.shape[0])]
    else:
        is_neg = s < 0
    return ['color: red;' if cell else 'color:black' 
            for cell in is_neg]
  
# Using apply method of style 
# attribute of Pandas DataFrame
df.style.apply(highlight_max)

输出：

示例 2：突出显示单元格而不是文本。

Python3

# Define a function which 
# returns the list for 
# df.style.apply() method
def highlight_max(s):
    if s.dtype == np.object:
        is_neg = [False for _ in range(s.shape[0])]
    else:
        is_neg = s < 0
    return ['background: red; color:white' 
            if cell else 'background:black; color:white' 
            for cell in is_neg]
  
# Using apply method of style 
# attribute of Pandas DataFrame
df.style.apply(highlight_max)

输出：

方法 2：使用dataframe.style.applymap()方法。

Syntax: DataFrame.style.applymap(self, func, subset=None, **kwargs)
Parameters:

func: It takes a scalar value and return the scalar values
subset: Set of columns or rows on which you want to call the func.
**kwargs: Pass along to func.

Returns: Styler object.

编程需要懂一点英语

示例 1：突出显示文本。

Python3

# Define a function for 
# colouring negative values 
# red and positive values black
def highlight_max(cell):
    if type(cell) != str and cell < 0 :
        return 'color: red'
    else:
        return 'color: black'
  
df.style.applymap(highlight_max)

输出：

示例 2：突出显示单元格而不是文本。

Python3

# Define a function which 
# returns string for 
# applymap() method
def highlight_max(cell):
    if type(cell) != str and cell < 0 :
        return 'background: red; color:black'
    else:
        return 'background: black; color: white'
  
df.style.applymap(highlight_max)

输出：

注意： pandas.DataFrame.applymap() 方法只将单个单元格传递给可调用函数，而 pandas.DataFrame.apply() 将 pandas.Series 传递给可调用函数。

参考： Pandas 中的样式