Convert Pandas DatetimeIndex to String

You can convert or cast pandas DatetimeIndex to String by using pd.to_datetime() and DatetimeIndex.strftime() functions. Pandas DatetimeIndex class is an Immutable ndarray that is used to store datetime64 data (internally stores as int64). When assigning a date field to an index it automatically converts into DatetimeIndex.

In this article, I will explain how to create an Index with DatatimeIndex and convert it to string format with multiple examples.

Key Points –

• Convert datetime values in the DatetimeIndex to strings using the strftime method.
• Provide a format string to specify the desired format of the string representation. This format string can include directives for year, month, day, hour, minute, second, etc.
• Common format directives include %Y for year, %m for month, %d for day, %H for hour, %M for minute, and %S for second.
• Take into account timezone information when converting datetime values to strings, ensuring that the resulting string representations accurately reflect the intended time zone or are appropriately adjusted if necessary.

Quick Examples of DataTime Index to String

If you are in a hurry, below are some quick examples of converting DatetimeIndex to String.

# Quick examples of datatime index to string

# Example 1: Convert DatetimeIndex to String
print(df.index.strftime('%m/%d/%Y, %r'))

# Example 2: Using index.format
print(pd.Series(df.index.format()))

# Example 3: Assign DatetimeIndex String Back to Index
df.index = df.index.strftime('%m/%d/%Y, %r')

Now, Let’s create a pandas DataFrame with a few rows and columns, execute these examples, and validate the results. Here, pandas.date_range() function is used to create dates between two dates with frequency daily.

# Create Pandas DataFrame.
import pandas as pd
df = pd.DataFrame({
    'Courses':["Spark","PySpark","Spark"],
    'Fee' :[22000,25000,23000],
    'Duration':['30days','50days','35days']
          })
df.index = pd.date_range('20210101','20210103',freq='D')
print("Create DataFrame:\n", df)
print("Type of the index:\n", type(df.index))

Yields below output.

Convert DatetimeIndex to String

As you see above, the type of df.index is DatetimeIndex, which you can use DatetimeIndex.strftime() to convert to a specific string format. The below example converts it into String with date format '%m/%d/%Y, %r'.

# Convert DatetimeIndex to String.
df1 = df.index.strftime('%m/%d/%Y, %r')
print("After converting datetimeindex to string:\n", df1)
print("Type of the index:\n", type(df1))

Yields below output.

Similarly, you can also use df.index.format() to convert DatetimeIndex. The Index.format() method returns an Index with formatted string representations of the elements in the index.

# Using Index.format
print(pd.Series(df.index.format()))

Yields below output.

# Output:
0    2021-01-01
1    2021-01-02
2    2021-01-03
dtype: object

Assign DatetimeIndex String Back to Index

You can assign this formatted DatetimeIndex String to Index but the index type would be Index with string values. Note that this is not a good practice as you would be losing the DatetimeIndex feature.

# Assign DatetimeIndex String Back to Index.
df.index = df.index.strftime('%m/%d/%Y, %r')
print(df)
print(type(df.index))

In this program, df.index.strftime('%m/%d/%Y, %r') converts the DatetimeIndex to strings in the specified format. Then, these strings are assigned back to the index of the DataFrame. Yields output same as above.

# Output:
                         Courses    Fee Duration
01/01/2021, 12:00:00 AM    Spark  22000   30days
01/02/2021, 12:00:00 AM  PySpark  25000   50days
01/03/2021, 12:00:00 AM    Spark  23000   35days
<class 'pandas.core.indexes.base.Index'>

Complete Examples of DataTimeIndex to String

# Create Pandas DataFrame.
import pandas as pd
import numpy as np
technologies= {
    'Courses':["Spark","PySpark","Spark"],
    'Fee' :[22000,25000,23000],
    'Duration':['30days','50days','35days']
          }
df = pd.DataFrame(technologies)
df.index = pd.date_range('20210101','20210103',freq='D')
print(df)
print(type(df.index))

# Example 1
print(pd.Series(df.index.format()))

# Example 2
print(df.index.strftime('%m/%d/%Y, %r'))

# Example 3
df.index = df.index.strftime('%m/%d/%Y, %r')
print(df)
print(type(df.index))

# Example 4
# Create column with date
df['date'] = pd.date_range('20210101','20210103',freq='D')

# Column date would be of type datetime64[ns]
print(df)
print(df.date.dtypes)

You can also find this example in the GitHub repository.

Frequently Asked Questions on Convert Pandas DatetimeIndex to String

Conclusion

In this article, I have explained how to convert DatetimeIndex to String format of pandas DataFrame index by using pd.to_datetime() and DatetimeIndex.strftime() functions with several examples.

Related Articles

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• Sort Pandas DataFrame by Date (Datetime)
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• pandas.to_datetime() – Examples
• Pandas Convert Integer to Datetime Type
• Pandas Convert Datetime to Date Column
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• Pandas Convert Column To DateTime
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• Pandas Convert Date (datetime) to String Format
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• Pandas Extract Month and Year from Datetime
• Pandas Convert Integer to String in DataFrame
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• Pandas Get Day, Month and Year from DateTime
• Select Pandas DataFrame Rows Between Two Dates
• Pandas Convert Multiple Columns To DateTime Type
• Convert Multiple Columns to String in Pandas DataFrame

References

• https://pandas.pydata.org/docs/getting_started/tutorials.html