从导入的 python 脚本中访问导入的 python 包时出现 NameError

Question

问题陈述：

我正在 Jupyter Notebook 中编写一个动态编写另一个脚本 (script.py) 的程序。编写 script.py 后，编写文件的函数通过 import 语句运行它，然后调用 script.py 中的函数。

我需要在 script.py 中使用 pandas，并在 script.py 的顶部导入它。在 script.py 的顶部执行 import pandas as pd 后，我得到了 NameError: name 'pd' is not defined。我最初尝试省略 import 语句，因为它已经在调用程序中执行，但我得到了同样的错误。我尝试将 import 语句放在 script.py 的函数中，但我得到了同样的错误。

Update2，已解决： 代码现在可以工作了。我很确定我唯一做的就是走开然后回来输入%debug，然后重新启动内核并运行所有单元。它没有找到要调试的回溯。我想你可以说这很神奇，但也许它正在重新启动内核。魔法对我来说更有意义，哈哈。

更新1： 原始示例代码实际上并未重现该错误。如果我要测试运行它，我最好将问题隔离在实际代码中。我的错。我仍然无法解决这个问题，但似乎构造写语句的循环有些东西搞砸了。因为在没有循环的情况下运行类似的代码一次。

这是我的真实代码：

import os
import pandas as pd

def read_files_in_folder(fp_list, path=None, arg_list=None):
    '''Reads a folder of csv tables into a dictionary of dataframes.
    Does this dynamically by writing a script to a file, importing the script,
    and running a function from the script.
    Parameters:
        fp_list is [str]: list of filenames or filepaths of csv files.
        path is str: (optional) filepath str filenames. os.curdir if None.
        arg_list is [str]: (optional) list of pd.read_csv() arguments to pass.
    Returns:
        df_dict is {pd.DataFrame}: dict of dataframes created from csv files.'''
    
    df_dict = {}
    
    if path is None:
        path = os.curdir
        
    if arg_list is None:
        for fp in fp_list:
            fp_var_name = fp.split('/')[-1].split('.')[0]
            df_dict[fp_var_name] = pd.read_csv(path + fp)
    else:
        args = ''
        for arg in arg_list:
            args += ', ' + arg
        with open('script.py', 'w') as file:
            file.write("""
import pandas as pd

def csvs_to_df_dict():
\tdf_dict = {}
""")
            for fp in fp_list:
                fp_var_name = fp.split('/')[-1].split('.')[0]
                statement = "\tdf_dict['" + fp_var_name + "'] = pd.read_csv('" + path + fp + "'" + args + ")\n"
                file.write(statement)
            file.write('\treturn df_dict')
        import script
        df_dict = script.csvs_to_df_dict()
    
    return df_dict

然后我执行：

csv_path = os.curdir + '/csv_tables/'
filename_list = os.listdir(path=csv_path)
df_dict = read_files_in_folder(fp_list=filename_list, path=csv_path,
                               arg_list=['index_col=0','skip_blank_lines=False'])
df_dict['abscorrup_idea.csv']

这写了script.py：

import pandas as pd

def csvs_to_df_dict():
    df_dict = {}
    df_dict['abscorrup_idea'] = pd.read_csv('./csv_tables/abscorrup_idea.csv', index_col=0, skip_blank_lines=False)
# ... ... ...
    df_dict['sorigeq_idea'] = pd.read_csv('./csv_tables/sorigeq_idea.csv', index_col=0, skip_blank_lines=False)
    return df_dict

但是，一旦它从df_dict = script.csvs_to_df_dict() 进入script.py，在script.py 的import pandas as pd 之后，它就会返回NameError: name 'pd' is not defined。完整的错误输出见下文。

如果您不传递 arg_list 并因此不首先创建 script.py 文件，它会起作用。所以，它适合我立即使用，但我想了解为什么它不能以其他方式工作。

我最初尝试将 script.py 编写为一系列语句而不是函数。我以为它会像我将该代码块插入到调用它的代码中一样运行，但是我无法从一个脚本调用df_dict 到另一个脚本。不同的命名空间？所以，我正在尝试一个函数。

这是完整的错误输出：

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-26-13999e7ca3af> in <module>
----> 1 df_dict = read_files_in_folder(fp_list=filename_list, path=csv_path,
      2                                arg_list=['index_col=0','skip_blank_lines=False'])

<ipython-input-25-4f1e04e89145> in read_files_in_folder(fp_list, path, arg_list)
     35             file.write('\treturn df_dict')
     36         import script
---> 37         df_dict = script.csvs_to_df_dict()
     38 
     39     return df_dict

~\OneDrive\Education\WGU\C749_intro_to_data_science\Module_3_Investigate_A_Dataset\Project\script.py in csvs_to_df_dict()
      1 
      2 import pandas as pd
----> 3 
      4 def csvs_to_df_dict():
      5     df_dict = {}

NameError: name 'pd' is not defined

更新前的原始示例，清理并正常运行：

例如：

# script1.py #
import pandas as pd

# The following is actually part of a function
# that is called later in the same script1,
# but I'm keeping it simple for the example.

df_dict = {}

with open('script2.py', 'w') as file:
    file.write("""
# script2.py #
import pandas as pd
def run_it():
\tdf_dict = {}
""")
    path = './csv_tables/'
    fn = 'abscorrup_idea.csv'
    file.write("\tdf_dict['abscorrup_idea'] = pd.read_csv('" + path + fn + "', index_col=0, skip_blank_lines=False)\n")
    file.write('\treturn df_dict')

import script2
df_dict = script2.run_it()
df_dict

这会写入以下文件，运行它并调用函数：

# script2.py #
import pandas as pd
def run_it():
    df_dict = {}
    df_dict['abscorrup_idea'] = pd.read_csv('./csv_tables/abscorrup_idea.csv', index_col=0, skip_blank_lines=False)
    return df_dict

Answer 1

我试图重现您的错误但失败了。当我只是复制粘贴您的代码时，我得到一个SyntaxError，因为您的转义有问题。但是这个

with open('script2.py', 'w') as file:
    file.write("""
# script2.py #
import pandas as pd
def run_it():
    df_dict = {}
    df_dict["test"] = pd.DataFrame(data={"test":[1,2,3]})
    return df_dict
""")

import script2
df_dict = script2.run_it()
df_dict["test"]

在我的机器上运行良好。请注意，我必须采用不同的示例 dataframe，因为我没有您的 csv 文件。

Answer 2

从帖子更新中可以看出，以下代码有效。重新启动内核似乎已经成功了。那就是魔法。

import os
import pandas as pd

def read_files_in_folder(fp_list, path=None, arg_list=None):
    '''Reads a folder of csv tables into a dictionary of dataframes.
    Does this dynamically by writing a script to a file, importing the script,
    and running a function from the script.
    Parameters:
        fp_list is [str]: list of filenames or filepaths of csv files.
        path is str: (optional) filepath str filenames. os.curdir if None.
        arg_list is [str]: (optional) list of pd.read_csv() arguments to pass.
    Returns:
        df_dict is {pd.DataFrame}: dict of dataframes created from csv files.'''
    
    df_dict = {}
    
    if path is None:
        path = os.curdir
        
    if arg_list is None:
        for fp in fp_list:
            fp_var_name = fp.split('/')[-1].split('.')[0]
            df_dict[fp_var_name] = pd.read_csv(path + fp)
    else:
        args = ''
        for arg in arg_list:
            args += ', ' + arg
        with open('script.py', 'w') as file:
            file.write("""
import pandas as pd

def csvs_to_df_dict():
\tdf_dict = {}
""")
            for fp in fp_list:
                fp_var_name = fp.split('/')[-1].split('.')[0]
                statement = "\tdf_dict['" + fp_var_name + "'] = pd.read_csv('" + path + fp + "'" + args + ")\n"
                file.write(statement)
            file.write('\treturn df_dict')
        import script
        df_dict = script.csvs_to_df_dict()
    
    return df_dict