英文:
Sorting a Dataframe column consisting of Sympy symbols
问题
# 导入所需的库
import sympy as sym
import pandas as pd
# 定义Sympy符号和对应的值
d1, c, bc = sym.symbols("δ, c, b_c")
values = [(d1, 1), (c, 2), (bc, 3)]
# 创建DataFrame
df = pd.DataFrame(values, columns=['Symbol', 'Value'])
# 使用.name方法对符号进行排序
sorted_df = df.sort_values(by='Symbol', key=lambda x: x['Symbol'].name)
# 打印排序结果
display(sorted_df)
请注意，以上是根据您提供的信息翻译的代码。如果您有任何问题或需要进一步的帮助，请随时告诉我。
英文:
I have a dataframe, where one column consists of Sympy symbols, and another column that consists of values.
import sympy as sym
import pandas as pd
d1,c,bc = sym.symbols("\delta, c, b_c")
values = [(d1,1),(c,2),(bc,3)]
df = pd.DataFrame(values, columns = ['Symbol', 'Value'])
df['Symbol'].sort_values()
When I run the above, I get the error (which was expected, because Sympy symbols aren't sortable themselves, but the actual string contained is sortable.
TypeError: cannot determine truth value of Relational
Sympy symbols are sortable if you can apply the .name method to them. I've done this with numpy arrays and lists of dictionaries:
import numpy as np
values = np.array(values, dtype = [('Symbol','O'),('Value','O')])
values = sorted(values, key = lambda x: x['Symbol'].name)
display(values)
Output:
>>[(\delta, 1), (b_c, 3), (c, 2)]
I'm wondering if it's possible with dataframes because I'd rather not convert to a different format to apply a sort.
答案1
得分: 2
我不确定这是否更有效，但也许你可以为数据框创建一个新列，例如'Symbol_names'，其中只包含名称，并按该列进行排序。你始终可以在之后删除该列。
df['Symbol_names'] = df['Symbol'].apply(lambda x: x.name)
df = df.sort_values('Symbol_names')\
.drop("Symbol_names", axis=1)\
.reset_index(drop=True) # 可选
英文:
I am not sure this is more efficient but perhaps you could create a new column e.g 'Symbol_names' for the data frame with names only and sort by that. You can always drop the column after
df['Symbol_names'] = df['Symbol'].apply(lambda x: x.name)
df = df.sort_values('Symbol_names')\
.drop("Symbol_names", axis=1)\
.reset_index(drop=True) # optional
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