Python Pandas - 基于底层分类创建索引
要基于底层分类创建索引,请使用 **pandas.CategoricalIndex()** 方法。
首先,导入所需的库 −
import pandas as pd
CategoricalIndex 是基于底层分类的索引。CategoricalIndex 可以采用有限的(通常是固定的)数量的可能值。使用“categories”参数设置分类的类别。使用“ordered”参数将分类视为有序 −
catIndex = pd.CategoricalIndex( ["p", "q", "r", "s","p", "q", "r", "s"], ordered=True, categories=["p", "q", "r", "s"] )
显示分类索引 −
print("Categorical Index...\n",catIndex)
获取分类 −
print("\nDisplayingCategories from CategoricalIndex...\n",catIndex.categories)
示例
以下是代码 −
import pandas as pd # CategoricalIndex is the Index based on an underlying Categorical # Set the categories for the categorical using the "categories" parameter # Treat the categorical as ordered using the "ordered" parameter catIndex = pd.CategoricalIndex( ["p", "q", "r", "s","p", "q", "r", "s"], ordered=True, categories=["p", "q", "r", "s"] ) # Display the Categorical Index print("Categorical Index...\n",catIndex) # Get the categories print("\nDisplayingCategories from CategoricalIndex...\n",catIndex.categories) # Get the min value print("\nMinimum value from CategoricalIndex...\n",catIndex.min()) # Get the max value print("\nMaximum value from CategoricalIndex...\n",catIndex.max())
输出
这将产生以下输出 −
Categorical Index... CategoricalIndex(['p', 'q', 'r', 's', 'p', 'q', 'r', 's'], categories=['p', 'q', 'r', 's'], ordered=True, dtype='category') DisplayingCategories from CategoricalIndex... Index(['p', 'q', 'r', 's'], dtype='object') Minimum value from CategoricalIndex... p Maximum value from CategoricalIndex... S
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