Python cumulative sum dataframe column
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The cumsum() function can be used to calculate the cumulative sum of values in a column of a pandas DataFrame. Show You can use the following syntax to calculate a reversed cumulative sum of values in a column: df['cumsum_reverse'] = df.loc[::-1, 'my_column'].cumsum()[::-1] This particular syntax adds a new column called cumsum_reverse to a pandas DataFrame that shows the reversed cumulative sum of values in the column titled my_column. The following example shows how to use this syntax in practice. Example: Calculate a Reversed Cumulative Sum in PandasSuppose we have the following pandas DataFrame that shows the total sales made by some store during 10 consecutive days: import pandas as pd #create DataFrame df = pd.DataFrame({'day': [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 'sales': [3, 6, 0, 2, 4, 1, 0, 1, 4, 7]}) #view DataFrame df day sales 0 1 3 1 2 6 2 3 0 3 4 2 4 5 4 5 6 1 6 7 0 7 8 1 8 9 4 9 10 7 We can use the following syntax to calculate a reversed cumulative sum of the sales column: #add new column that shows reverse cumulative sum of sales
df['cumsum_reverse_sales'] = df.loc[::-1, 'sales'].cumsum()[::-1]
#view updated DataFrame
df
day sales cumsum_reverse_sales
0 1 3 28
1 2 6 25
2 3 0 19
3 4 2 19
4 5 4 17
5 6 1 13
6 7 0 12
7 8 1 12
8 9 4 11
9 10 7 7The new column titled cumsum_reverse_sales shows the cumulative sales starting from the last row. Here’s how we would interpret the values in the cumsum_reverse_sales column:
And so on. Additional ResourcesThe following tutorials explain how to perform other common tasks in pandas: How to Sum Specific Columns in Pandas OverviewThe
Syntax
Syntax for the cumsum() function in pandas Parameters
Return valueThis function returns a Series or DataFrame object showing the cumulative maximum in the axis. Example
Syntax for the cumusum() function Explanation
CONTRIBUTOR How do you do a cumulative sum in a DataFrame in Python?The cumsum() method returns a DataFrame with the cumulative sum for each row. The cumsum() method goes through the values in the DataFrame, from the top, row by row, adding the values with the value from the previous row, ending up with a DataFrame where the last row contains the sum of all values for each column.
How do you make a cumulative column in Python?Cumulative sum of a column in Pandas can be easily calculated with the use of a pre-defined function cumsum().. Syntax: cumsum(axis=None, skipna=True, *args, **kwargs). Parameters:. axis: {index (0), columns (1)}. skipna: Exclude NA/null values. ... . Returns: Cumulative sum of the column.. How do you find the sum of a column in pandas?Pandas DataFrame sum() Method
The sum() method adds all values in each column and returns the sum for each column. By specifying the column axis ( axis='columns' ), the sum() method searches column-wise and returns the sum of each row.
How does cumulative sum work?The cumulative sum can be defined as the sum of a set of numbers as the sum value grows with the sequence of numbers.
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