how to count number of columns in pandas code example

Example 1: pandas dataframe get number of columns

import pandas as pd
df = pd.DataFrame({"pear": [1,2,3], "apple": [2,3,4], "orange": [3,4,5]})

len(df.columns)
3

Example 2: python count variable and put the count in a column of data frame

df['freq'] = df.groupby('myvar')['myvar'].transform('count')