Home / Questions / 265989
Accepted
efueyo
Asked: 2020-05-23 14:30:59 +0800 CST 2020-05-23 14:30:59 +0800 CST

TypeError: 'dict' object is not callable

  • 772

I have the following dataframe:

data.info()
<class 'pandas.core.frame.DataFrame'>
DatetimeIndex: 658 entries, 2016-01-04 to 2019-01-31
Data columns (total 4 columns):
Equity    658 non-null float64
Equity    658 non-null float64
Equity    658 non-null float64
Equity    658 non-null float64
dtypes: float64(4)
memory usage: 25.7 KB

I try to rename the columns.

old_names = ['Equity', 'Equity', 'Equity', 'Equity' ] 
new_names = ['Equity1','Equity2', 'Equity3','Equity4' ]
data.rename(columns=dict(zip(old_names, new_names)), inplace=True)

It returns the error.

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-123-9f8bfefe3429> in <module>
      1 old_names = ['Equity', 'Equity', 'Equity', 'Equity' ]
      2 new_names = ['Equity1','Equity2', 'Equity3','Equity4' ]
----> 3 data.rename(columns=dict(zip(old_names, new_names)), inplace=True)

TypeError: 'dict' object is not callable

What can be the cause?. I will appreciate your help.

python

1 Answers

  1. Best Answer

    A dictionary is a perfectly valid object for the argument columnsof pandas.DataFrame.rename. Your error is almost certainly due to the fact that before these lines in your module you have redefined the built-in type (class) dict. It's very easy to reproduce your error:

    >>> type(dict)
<class 'type'>

>>> a = dict([["a", 4]])
>>> type(a)         
<class 'dict'>

>>> dict = a 
>>> b = dict([["b", 5]])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'dict' object is not callable

>>> type(dict)
<class 'dict'>

    With dict = a(o dict = {}) you reassign dictthe reference to an object to the identifier dict, so from now on, dictit is not a class that you can instantiate to create a new dictionary, it is an object of this class, and a dictionary is not callable ( {"a": 4}()) .

    As a general rule, you should never use the names of the built-ins or modules of the stdlib to name your own variables, at most (if there is no better name) use the name followed by an underscore as the conventions mark:

     dict_ = {"a": 4}

    That said, even correcting the above, as you are doing, you will not be able to rename the columns:

    >>> old_names = ['Equity', 'Equity', 'Equity', 'Equity' ] 
>>> new_names = ['Equity1','Equity2', 'Equity3','Equity4' ]
>>> dict(zip(old_names, new_names))
{'Equity': 'Equity4'}

    zip(old_names, new_names)generate:

    (('Equity', 'Equity1'), ('Equity', 'Equity2'), ('Equity', 'Equity3'), ('Equity', 'Equity4'))

    when we use dictover the above we get:

    {'Equity': 'Equity4'}

    This happens because dictionaries have a unique key , so only the last pair, , remains ('Equity', 'Equity4'). It will finally result in a DataFrame with all columns renamed asEquity4

    For your case, just reassign the new names using the attribute DataFrame.columns:

    new_names = ['Equity1','Equity2', 'Equity3','Equity4' ]
data.columns = new_names
    • 3