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Extract week number from date in Pandas-Python

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  • Last Updated : 10 Jul, 2020

Many times, when working with some data containing dates we may need to extract the week number from a particular date. In Python, it can be easily done with the help of pandas.

Example 1:




# importing pandas as pd
import pandas as pd 
  
# creating a dictionary containing a date
dict = {'Date':["2015-06-17"]}
  
# converting the dictionary to a dataframe
df = pd.DataFrame.from_dict(dict)
  
# converting the date to the required format
df['Date'] = pd.to_datetime(df['Date'], errors ='coerce')
df.astype('int64').dtypes
  
# extracting the week from the date
weekNumber = df['Date'].dt.week
  
print(weekNumber)

Output:

0    25
Name: Date, dtype: int64

Example 2: We can also do the same for multiple dates by adding more dates in the ‘Date’ object.




# importing pandas as pd
import pandas as pd 
  
# creating a dictionary containing a date
dict = {'Date':["2020-06-17", "2020-01-14"
                "2020-09-20", "2020-08-15"]}
  
# converting the dictionary to a 
# dataframe
df = pd.DataFrame.from_dict(dict)
  
# converting the date to the required 
# format
df['Date'] = pd.to_datetime(df['Date'],
                            errors ='coerce')
df.astype('int64').dtypes
  
# extracting the week from the date
weekNumber = df['Date'].dt.week
  
print(weekNumber)

Output:

python-extract-week-number

Example 3: Extracting week number from dates for multiple dates using date_range() and to_series().

  • pandas.data_range(): It generates all the dates from the start to end date

    Syntax:

    pandas.date_range(start, end, periods, freq, tz, normalize, name, closed)

  • pandas.to_series(): It creates a Series with both index and values equal to the index keys.

    Syntax:

    Index.to_series(self, index, name)




# importing pandas as pd
import pandas as pd 
  
# generating all dates in given range
# with increment by days
allDates = pd.date_range('2020-06-27', '2020-08-03', freq ='W')
  
# converting dates to series
series = allDates.to_series()
  
series.dt.week

Output:

pandas-extract-week-number-2

Example 4: In this example, we’ll be using pandas.Series() to generate dates and use a different way to convert the series to the dataframe.

pandas.Series(): Used to create a one-dimensional ndarray with axis labels.
Syntax:

pandas.Series(data, index, dtype, name, copy, fastpath)




# importing pandas as pd
import pandas as pd 
  
# generating the series
dates = pd.Series(pd.date_range('2020-2-10',
                                periods = 5,
                                freq ='M'))
  
# converting to dataframe
df = pd.DataFrame({'date_given': dates})
  
# extracting the week number
df['week_number'] = df['date_given'].dt.week
  
df

Output:

pandas-extract-week-number-5


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