Python | Pandas dataframe.eval() Last Updated : 20 Nov, 2018 Summarize Comments Improve Suggest changes Share Like Article Like Report Python is a great language for doing data analysis, primarily because of the fantastic ecosystem of data-centric python packages. Pandas is one of those packages and makes importing and analyzing data much easier. Pandas dataframe.eval() function is used to evaluate an expression in the context of the calling dataframe instance. The expression is evaluated over the columns of the dataframe. Syntax: DataFrame.eval(expr, inplace=False, **kwargs) Parameters: expr : The expression string to evaluate. inplace : If the expression contains an assignment, whether to perform the operation inplace and mutate the existing DataFrame. Otherwise, a new DataFrame is returned. kwargs : See the documentation for eval() for complete details on the keyword arguments accepted by query(). Returns: ret : ndarray, scalar, or pandas object Example #1: Use eval() function to evaluate the sum of all column element in the dataframe and insert the resulting column in the dataframe. Python3 # importing pandas as pd import pandas as pd # Creating the dataframe df=pd.DataFrame({"A":[1,5,7,8], "B":[5,8,4,3], "C":[10,4,9,3]}) # Print the first dataframe df Let's evaluate the sum over all the columns and add the resultant column to the dataframe Python3 1== # To evaluate the sum over all the columns df.eval('D = A + B+C', inplace = True) # Print the modified dataframe df Output : Example #2: Use eval() function to evaluate the sum of any two column element in the dataframe and insert the resulting column in the dataframe. The dataframe has NaN value. Note : Any expression can not be evaluated over NaN values. So the corresponding cells will be NaN too. Python3 # importing pandas as pd import pandas as pd # Creating the dataframe df=pd.DataFrame({"A":[1,2,3], "B":[4,5,None], "C":[7,8,9]}) # Print the dataframe df Let's evaluate the sum of column "B" and "C". Python3 1== # To evaluate the sum of two columns in the dataframe df.eval('D = B + C', inplace = True) # Print the modified dataframe df Output : Notice, the resulting column 'D' has NaN value in the last row as the corresponding cell used in evaluation was a NaN cell. Comment More infoAdvertise with us Next Article Pandas DataFrame.astype()-Python S Shubham__Ranjan Follow Improve Article Tags : Technical Scripter Python Python-pandas Python pandas-dataFrame Pandas-DataFrame-Methods +1 More Practice Tags : python Similar Reads Python | Pandas Dataframe.iat[ ] Python is a great language for doing data analysis, primarily because of the fantastic ecosystem of data-centric Python packages. Pandas is one of those packages and makes importing and analyzing data much easier. Pandas iat[] method is used to return data in a dataframe at the passed location. The 2 min read Python | Pandas dataframe.get() Python is a great language for doing data analysis, primarily because of the fantastic ecosystem of data-centric python packages. Pandas is one of those packages and makes importing and analyzing data much easier. Pandas dataframe.get() function is used to get item from object for given key. The key 2 min read Python | Pandas Dataframe.at[ ] Python is a great language for doing data analysis, primarily because of the fantastic ecosystem of data-centric Python packages. Pandas is one of those packages and makes importing and analyzing data much easier. Pandas at[] is used to return data in a dataframe at the passed location. The passed l 2 min read Python | Pandas DataFrame.values Pandas DataFrame is a two-dimensional size-mutable, potentially heterogeneous tabular data structure with labeled axes (rows and columns). Arithmetic operations align on both row and column labels. It can be thought of as a dict-like container for Series objects. This is the primary data structure o 2 min read Pandas DataFrame.astype()-Python DataFrame.astype() function in pandas cast a pandas object such as a DataFrame or Series to a specified data type. This is especially useful when you need to ensure that columns have the correct type, such as converting strings to integers or floats to strings. For example:Pythonimport pandas as pd 3 min read Python | Pandas dataframe.applymap() Python is a great language for doing data analysis, primarily because of the fantastic ecosystem of data-centric python packages. Pandas is one of those packages and makes importing and analyzing data much easier. Dataframe.applymap() method applies a function that accepts and returns a scalar to ev 2 min read Like