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How to obtain the cumulative maximum over a DataFrame axis
Onyejiaku Theophilus ChidaluOverview
We use the cummax() function of a DataFrame object to obtain the cumulative maximum over its axis.
Axis here represents the row and column of the DataFrame. The axis with a value of
'0'indicates the axes that run vertically downwards across a row, while a value of'1'shows the axes that run horizontally across a column.
Syntax
The cummax() function takes the syntax shown below:
DataFrame.cummax(axis=None, skipna=True, *args, **kwargs)
Syntax for the cummax() function in Pandas
Parameters
The cummax() function takes the following parameter values:
axis: This represents the name for the row (designated as0or'index') or the column (designated as1orcolumns) axis.skipna(optional): This takes a Boolean value indicating if NA or null values are to be excluded or not.args,**kwargs(optional): These are keywords that have no effect but may be accepted for compatibility with NumPy.
Return value
The cummax() function returns a Series or DataFrame object showing the cumulative maximum in the axis.
Example
# A code to illustrate the cummax() function in Pandas
# importing the pandas library
import pandas as pd
# creating a dataframe
df = pd.DataFrame([[5,10,4,15,3],
[1,7,5,9,0.5],
[3,11,13,14,12]],
columns=list('ABCDE'))
# printing the dataframe
print(df)
# obtaining the cummulative maximum vertically across rows
print(df.cummax(axis="index"))
# obtaining the cummulative maximum horizontally over columns
print(df.cummax(axis="columns"))Syntax for the cummax() function
Explanation
- Line 4 : We import the pandas library.
- Lines 7-10: We create a dataframe
df. - Line 12: We print the dataframe,
df. - Line 15: We obtain the cumulative maximum values running downwards across the rows (axis
0). We print the result to the console. - Line 18: We obtain the cumulative maximum values running horizontally across columns (axis
1). We print the result to the console.
RELATED TAGS
pandas
python
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