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Pandas Articles
Page 29 of 42
How to check if a column exists in Pandas?
To check if a column exists in a Pandas DataFrame, we can take the following Steps −StepsCreate a two-dimensional, size-mutable, potentially heterogeneous tabular data, df.Print the input DataFrame, df.Initialize a col variable with column name.Create a user-defined function check() to check if a column exists in the DataFrame.Call check() method with valid column name.Call check() method with invalid column name.Exampleimport pandas as pd def check(col): if col in df: print "Column", col, "exists in the DataFrame." else: print "Column", col, "does not exist in the DataFrame." df = pd.DataFrame( ...
Read MoreCount the frequency of a value in a DataFrame column in Pandas
To count the frequency of a value in a DataFrame column in Pandas, we can use df.groupby(column name).size() method.StepsCreate a two-dimensional, size-mutable, potentially heterogeneous tabular data, df.Print the input DataFrame, df.Print frequency of column, x.Print frequency of column, y.Print frequency of column, z.Exampleimport pandas as pd df = pd.DataFrame( { "x": [5, 2, 1, 5], "y": [4, 10, 5, 10], "z": [1, 1, 5, 1] } ) print "Input DataFrame is:", df col = "x" count = df.groupby('x').size() print "Frequency of values in column ", col, "is:", ...
Read MoreHow to use the apply() function for a single column in Pandas?
We can use apply() function on a column of a DataFrame with lambda expression.StepsCreate a two-dimensional, size-mutable, potentially heterogeneous tabular data, df.Print input DataFrame, df.Override column x with lambda x: x*2 expression using apply() method.Print the modified DataFrame.Exampleimport pandas as pd df = pd.DataFrame( { "x": [5, 2, 1, 5], "y": [4, 10, 5, 10], "z": [1, 1, 5, 1] } ) print "Input DataFrame is:", df df['x'] = df['x'].apply(lambda x: x * 2) print "After applying multiplication of 2 DataFrame is:", dfOutputInput DataFrame is: x y z 0 5 4 1 1 2 10 1 2 1 5 5 3 5 10 1 After applying multiplication of 2 DataFrame is: x y z 0 10 4 1 1 4 10 1 2 2 5 5 3 10 10 1
Read MoreHow to sort multiple columns of a Pandas DataFrame?
To sort multiple columns of a Pandas DataFrame, we can use the sort_values() method.StepsCreate a two-dimensional, size-mutable, potentially heterogeneous tabular data, df.Print the input DataFrame, df.Initialize a variable col to sort the column.Print the sorted DataFrame.Exampleimport pandas as pd df = pd.DataFrame( { "x": [5, 2, 7, 0], "y": [4, 7, 5, 1], "z": [9, 3, 5, 1] } ) print "Input DataFrame is:", df col = ["x", "y"] df = df.sort_values(col, ascending=[False, True]) print "After sorting column ", col, "DataFrame is:", dfOutputInput DataFrame is: x y z 0 5 4 9 1 2 7 3 2 7 5 5 3 0 1 1 After sorting column ['x', 'y'] DataFrame is: x y z 2 7 5 5 0 5 4 9 1 2 7 3 3 0 1 1
Read MoreHow to select all columns except one in a Pandas DataFrame?
To select all columns except one column in Pandas DataFrame, we can use df.loc[:, df.columns != ].StepsCreate a two-dimensional, size-mutable, potentially heterogeneous tabular data, df.Print the input DataFrame, df.Initialize a variable col with column name that you want to exclude.Use df.loc[:, df.columns != col] to create another DataFrame excluding a particular column.Print the DataFrame without col column.Exampleimport pandas as pd df = pd.DataFrame( { "x": [5, 2, 1, 9], "y": [4, 1, 5, 10], "z": [4, 1, 5, 0] } ) print("Input DataFrame is:", df) col = ...
Read MoreHow to get a value from the cell of a Pandas DataFrame?
To get a value from the cell of a DataFrame, we can use the index and col variables.StepsCreate a two-dimensional, size-mutable, potentially heterogeneous tabular data, df.Print the input DataFrame, df.Initialize the index variable.Initialize the col variable.Get the cell value corresponding to index and col variable.Print the cell value.Exampleimport pandas as pd df = pd.DataFrame( { "x": [5, 2, 1, 9], "y": [4, 1, 5, 10], "z": [4, 1, 5, 0] } ) print("Input DataFrame is:", df) index = 2 col = "y" cell_val = df.iloc[index][col] print "Cell ...
Read MoreDifferent Types of Joins in Pandas
Pandas is one of the popular libraries used to perform data analysis and data manipulation. There are many advanced features to work with the tabular data such as join multiple data frames into one depending upon the common columns or indices of columns. In python, there are different types of joins available which can be performed by using the merge() function along with the how parameter of the pandas library. Following are the different joins. Inner Join Outer Join Left Join Right Join Cross Join Inner Join An Inner Join in the pandas library will return the rows ...
Read MoreHow to Scale Pandas DataFrame Columns?
Scaling is the process of preprocessing the data in data analysis and ensuring that all the features in a dataset have similar ranges, making them more comparable and reducing the impact of different scales on machine learning algorithms. We can scale Pandas dataframe columns using methods like Min-max scaling, standardization, Robust scaling, and log transformation. In this article we will dive into the process of scaling pandas dataframe scaling using various methods. Why Scaling is Important? Some features in the data may have larger values which can dominate when the analysis or model training is done. Scaling ensures ...
Read MoreAppend data to an empty Pandas DataFrame
Introduction A data structure known as a data frame is a two-dimensional labelled array with columns that might be of various data kinds. You can compare it to a spreadsheet, a SQL table, or even a dict of Series objects to better understand it. It is the panda item that is used the vast majority of the time. In addition to the data itself, you have the option of also passing parameters for the index (row labels) and columns (column labels). If you supply an index and/or columns, you are assuring that those elements will be present in the DataFrame ...
Read MoreOne Hot Encoding and Label Encoding Explained
Introduction Categorical variables are extensively utilized in data analysis and machine learning. Many algorithms are incapable of directly processing these variables, and they must be encoded or translated into numerical data before they can be used. Hot encoding and label encoding are two popular methods for encoding categorical data. One hot encoding provides a binary vector for each category in a categorical variable, indicating whether that category exists or not. We will discuss the ideas of one hot encoding and label encoding, as well as their advantages and disadvantages, and present examples of when and how to ...
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