DataFrame构造函数未正确调用！错误 [英] DataFrame constructor not properly called! error

问题描述

我是python的新手，在以键和值的格式(即

I am new to python and i am facing problem in creating the Dataframe in the format of key and value i.e.

data = [{'key':'\[GlobalProgramSizeInThousands\]','value':'1000'},]

这是我的代码

columnsss = ['key','value'];
query = "select * from bparst_tags where tag_type = 1 ";
result = database.cursor(db.cursors.DictCursor);
result.execute(query);
result_set = result.fetchall();
data = "[";
for row in result_set:
`row["tag_expression"]`)
    data +=  "{'value': %s , 'key': %s }," % ( `row["tag_expression"]`, `row["tag_name"]` )
data += "]" ;    
df = DataFrame(data , columns=columnsss); 

但是当我在DataFrame中传递数据时，它显示了我 pandas.core.common.PandasError:DataFrame构造函数未正确调用！.

But when i pass the data in DataFrame it shows me pandas.core.common.PandasError: DataFrame constructor not properly called!.

如果我打印数据并将相同的值分配给data变量，那么它将起作用.

while if i print the data and assign the same value to data variable then it works.

推荐答案

您要向DataFrame构造函数提供字典的字符串表示形式，而不是字典本身.因此，这就是您收到该错误的原因.

You are providing a string representation of a dict to the DataFrame constructor, and not a dict itself. So this is the reason you get that error.

因此，如果您想使用代码，则可以执行以下操作:

So if you want to use your code, you could do:

df = DataFrame(eval(data))

但是最好不要首先创建字符串，而是直接将其放入字典中.大致类似:

But better would be to not create the string in the first place, but directly putting it in a dict. Something roughly like:

data = []
for row in result_set:
    data.append({'value': row["tag_expression"], 'key': row["tag_name"]})

但是也许甚至不需要这样做，因为根据您result_set中的确切内容，您可能会:

But probably even this is not needed, as depending on what is exactly in your result_set you could probably:

• 直接将其提供给DataFrame:DataFrame(result_set)
• 或使用熊猫read_sql_query函数为您执行此操作(请参见

• provide this directly to a DataFrame: DataFrame(result_set)
• or use the pandas read_sql_query function to do this for you (see docs on this)

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