如何根据特定条件用列表值替换 Pandas Dataframes 中的元素？

如何解决如何根据特定条件用列表值替换 Pandas Dataframes 中的元素？

我有一个 CSV 文件，其中包含 2 列，查询和描述。这是文件的示例描述：-

| Query                                        | Description |
| --------                                     | -------------- |
| What is the type of \<mach-name> machine>    |  \<mach-name> is ...       |
| What is the use of \<mach-name> machine>     |  The use of \<mach-name> is ...         |
| How long it takes to rain in \<state-name>   | It rains for ... hours in \<state-name>          |
| What is the best restaurant in \<state-name> | \<state-name>'s best food is in ...         |
|
...
etc.

每个查询列和描述列都有这样的唯一字符串。假设通过 Pandas 将 CSV 文件读入数据帧 df。目标是根据特定条件替换\<>类型的元素，例如\<mach-name>等。

需要通过将标签 替换为相应的列表元素来进行这些替换。

mach_name = ["Drilling","ABC",XYZ".... etc.]
state_name = ["New York","London","Delhi"... etc.]

示例：if(\<mach-name>) 出现在任何行的查询和说明列中，替换 mach_name 列表中相应元素的标签。所以，例如如果 mach_name 列表有 10 个元素，则需要将更多这样的句子附加到数据框 df。 预期的输出是这样的：

| Query                                   | Description |
| --------                                | -------------- |
| What is the type of Drilling machine.   |  Drilling is ...        |
| What is the type of ABC machine.        |  ABC is ...        |
| What is the type of XYZ machine.        |  XYZ is ...      |
| What is the use of Drilling machine     |  The use of Drilling is ...        |
| What is the use of ABC machine          |  The use of ABC is ...       |
| What is the use of XYZ machine.         |  The use of XYZ is ...       |
| How long it takes to rain in New York   | It rains for ... hours in New York          |
| How long it takes to rain in London     | It rains for ... hours in London          |
| How long it takes to rain in Delhi      | It rains for ... hours in Delhi          |

| What is the best restaurant in New York | New York's best food is in ...         |
| What is the best restaurant in London   | London's best food is in ...         |
| What is the best restaurant in Delhi    |Delhi's best food is in ...         |
|

....等

例如，我希望使用 str.replace() 执行简单的 Python 替换，但它可能会涉及用于迭代 Pandas 数据帧的 for 循环，因此答案建议不要迭代数据帧，而是我找不到一种明确的方法来根据这些条件替换值，同时还根据列表元素附加新行。任何帮助/指导表示赞赏。谢谢。

解决方法

如果您读取原始 csv，处理它，然后将结果转换为 Pandas 数据帧，这会更容易，但如果您之前需要读取数据帧，这可能是一个选项：

data=[ {"query": "What is the type of \<mach-name> machine>","description": "\<mach-name> is ..."},{"query": "What is the use of \<mach-name> machine>","description": "The use of \<mach-name> is ..."},{"query": "How long it takes to rain in \<state-name>","description": "It rains for ... hours in \<state-name>"}]
      
df = pd.DataFrame(data)

#mark rows that should that satisfy the conditions
df["replace_mach"] = df['query'].str.contains('\<mach-name>') &\ 
                     df['description'].str.contains('\<mach-name>')
df["replace_state"] = df['query'].str.contains('\<state-name>') &\ 
                      df['description'].str.contains('\<state-name>')


dfs_list = []
mach_name = ["Drilling","ABC","XYZ"]
state_name = ["New York","London","Delhi"]


for n in mach_name:
    aux = df[df["replace_mach"]].copy()
    aux["query"] = aux["query"].str.replace(r"\\<mach-name>",n)
    aux["description"] = aux["description"].str.replace(r"\\<mach-name>",n)
    dfs_list.append(aux)
    
for n in state_name:
    aux = df[df["replace_state"]].copy()
    aux["query"] = aux["query"].str.replace(r"\\<state-name>",n)
    aux["description"] = aux["description"].str.replace(r"\\<state-name>",n)
    dfs_list.append(aux)
    
# add records without wild cards to dataframe
dfs_list.append(df[~((df["replace_mach"])|(df["replace_state"]))]

replaced_df = pd.concat(dfs_list)
replaced_df