NameError: name 'time' or 'datetime' is not defined in Python

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Borislav Hadzhiev

Last updated: Apr 8, 2024
10 min

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# Table of Contents

  1. NameError: name 'TIME' is not defined in Python
  2. NameError: name 'DATETIME' is not defined in Python
  3. NameError: name 'TIMEDELTA' is not defined in Python
  4. NameError: name 'RE' is not defined in Python
  5. NameError: name 'CSV' is not defined in Python

Make sure to click on the correct subheading depending on your error message.

# NameError: name 'time' is not defined in Python

The Python "NameError: name 'time' is not defined" occurs when we use the time module without importing it first.

To solve the error, import the time module before using it - import time.

nameerror name time is not defined

Here is an example of how the error occurs.

main.py
# ⛔️ NameError: name 'time' is not defined
time.sleep(1)

print(
    time.strftime(
        "%a, %d %b %Y %H:%M:%S +0000", time.gmtime()
    )
)

# Import the time module before using it

To solve the error, we have to import the time module.

main.py
# 👇️ First import time module
import time

time.sleep(1)

print(
    time.strftime(
        "%a, %d %b %Y %H:%M:%S +0000", time.gmtime()
    )
)

import time module before using it

Even though the time module is in the Python standard library, we still have to import it before using it.

Make sure you haven't used a capital letter t when importing time because module names are case-sensitive.

# Make sure to not import the time module in a nested scope

Also, make sure you haven't imported time in a nested scope, e.g. a function.

main.py
def get_time():
    import time

    time.sleep(1)

    print(
        time.strftime(
            "%a, %d %b %Y %H:%M:%S +0000", time.gmtime()
        )
    )


# ⛔️ NameError: name 'time' is not defined
time.sleep(1)

importing time module in nested scope

We imported the time module in a function, so we aren't able to use it outside of the function.

Import the module at the top level to be able to use it throughout your code.

main.py
# ✅ Moved import to the top level
import time


def get_time():

    time.sleep(1)

    print(
        time.strftime(
            "%a, %d %b %Y %H:%M:%S +0000", time.gmtime()
        )
    )


time.sleep(1)

move time module import to top level

The import statement for the time module has to come at the top of the file before any code that makes use of it.

# Make sure to not import the time module in a try/except statement

You also should be importing the time module in a try/except statement.

main.py
try:
    import time

    time.sleep(1)

    print(
        time.strftime(
            "%a, %d %b %Y %H:%M:%S +0000", time.gmtime()
        )
    )
except ImportError:
    time.sleep(1)

time.sleep(1)

The code sample works, however, if the code in the try statement raises an error, the time module won't get imported successfully.

This would cause the error because we are trying to access properties on the time module in the outer scope and the except block.

Instead, move the import statement to the top of the file.

main.py
# ✅ Moved import statement to the top of the file
import time

try:

    time.sleep(1)

    print(
        time.strftime(
            "%a, %d %b %Y %H:%M:%S +0000", time.gmtime()
        )
    )
except ImportError:
    time.sleep(1)

time.sleep(1)

# Only importing the functions you need from the time module

Alternatively, you can make your code a little more concise by only importing the functions that you use in your code.

main.py
from time import sleep, strftime, gmtime

sleep(1)

print(
    strftime(
        "%a, %d %b %Y %H:%M:%S +0000", gmtime()
    )
)

The example shows how to import the sleep() and strftime() and gmtime functions from the time module.

Instead of accessing the members on the module, e.g. time.sleep(), we now access them directly.

This should be your preferred approach because it makes your code easier to read.

For example, when we use an import such as import time, it is much harder to see which functions from the time module are used in the file.

Conversely, when we import specific functions, it is much easier to see which functions from the time module are used.

The time module provides many time-related functions.

You can view all of the functions and constants the module provides by visiting the official docs.

# NameError: name 'sleep' is not defined in Python

If you get an error message such as "NameError: name 'sleep' is not defined", then you have forgotten to import the sleep function from the time module.

nameerror name sleep is not defined

Here is an example of how the error occurs.

main.py
# ⛔️ NameError: name 'sleep' is not defined
sleep(3)

print('After 3 seconds')

To solve the error, we have to import the sleep function from the time module.

main.py
# 👇️ import the sleep function
from time import sleep

sleep(3) # 👈️ time in seconds

print('After 3 seconds')

Alternatively, you can import the time module and access the sleep function as time.sleep(N).

main.py
import time

time.sleep(3)

print('After 3 seconds')

The sleep function takes a number of seconds as a parameter and suspends execution for the given number of seconds.

If you need to call a function or run some logic every N seconds, use a while loop.

main.py
import time

while True:
    print('Runs every 3 seconds')
    time.sleep(3)

The code in the body of the while loop is run every 3 seconds.

You can also pass a floating point number as an argument to sleep if you need to suspend execution for X.Y seconds.

main.py
import time

time.sleep(2.5)

print('After 2.5 seconds')

Note that the sleep() function suspends execution at least for the provided number of seconds, except in the case when an exception is raised.

# NameError: name 'datetime' is not defined in Python

The Python "NameError: name 'datetime' is not defined" occurs when we use the datetime module without importing it first.

To solve the error, import the datetime module before using it - import datetime.

nameerror name datetime is not defined

Here is an example of how the error occurs.

main.py
# ⛔️ NameError: name 'datetime' is not defined
print(datetime.date.today())

d = datetime.date(2022, 9, 24)
print(d)

t = datetime.time(9, 30)
print(t)

# Import the datetime module before using it

To solve the error, we have to import the datetime module before using it.

main.py
import datetime

print(datetime.date.today())

d = datetime.date(2022, 9, 24)
print(d)  # 👉️ "2022-09-24"

t = datetime.time(9, 30)
print(t)  # 👉️ 09:30:00

Even though the datetime module is in the Python standard library, we still have to import it before using it.

Make sure you haven't used a capital letter d when importing datetime because module names are case-sensitive.

# Make sure to not import the datetime module in a nested scope

Also, make sure you haven't imported datetime in a nested scope, e.g. a function.

main.py
def get_datetime():
    import datetime

    print(datetime.date(2023, 9, 24))


# ⛔️ NameError: name 'datetime' is not defined
print(datetime.date(2023, 9, 24))

We imported the datetime module in a function, so we aren't able to use it outside of the function.

Import the module at the top level to be able to use it throughout your code.

main.py
# ✅ Moved the import to the top level of the file
import datetime


def get_datetime():

    print(datetime.date(2023, 9, 24))


print(datetime.date(2023, 9, 24))

The import statement for the datetime module has to come at the top of the file before any code that makes use of it.

# Don't import the datetime module in a try/except statement

You also should be importing the datetime module in a try/except statement.

main.py
try:
    # 👉️ Code here could raise an error

    import datetime

    print(datetime.date(2023, 9, 24))
except ImportError:
    print(datetime.date(2023, 9, 24))


print(datetime.date(2023, 9, 24))

The code sample works, however, if the code in the try statement raises an error, the datetime module won't get imported successfully.

This would cause the error because we are trying to access properties on the datetime module in the outer scope and the except block.

Instead, move the import statement to the top of the file.

main.py
# ✅ Moved the import statement to the top of the file
import datetime

try:
    print(datetime.date(2023, 9, 24))
except ImportError:
    print(datetime.date(2023, 9, 24))


print(datetime.date(2023, 9, 24))

# Importing functions directly from the datetime module

Alternatively, you can make your code a little more concise by only importing the classes that you use in your code.

main.py
from datetime import date, time

print(date.today())

d = date(2022, 9, 24)
print(d)  # "2022-09-24"

t = time(9, 30)
print(t)  # 👉️ 09:30:00

The example shows how to import the date() and time() classes from the datetime module.

Instead of accessing the members on the module, e.g. datetime.date(), we now access them directly.

This should be your preferred approach because it makes your code easier to read.

For example, when we use an import such as import datetime, it is much harder to see which classes from the datetime module are being used in the file.

Conversely, when we import specific functions or classes, it is much easier to see which classes from the datetime module are being used.

The datetime module provides classes for manipulating dates and times.

You can view all of the classes and constants the datetime module provides by visiting the official docs.

# NameError: name 'timedelta' is not defined in Python

The Python "NameError: name 'timedelta' is not defined" occurs when we use the timedelta class without importing it first.

To solve the error, import the timedelta class before using it - from datetime import timedelta.

nameerror name timedelta is not defined

Here is an example of how the error occurs.

main.py
# ⛔️ NameError: name 'timedelta' is not defined
delta = timedelta(
    days=30,
    seconds=45,
    microseconds=10,
    milliseconds=29000,
    minutes=3,
    hours=7,
    weeks=2,
)

print(delta)

print(delta.max)
print(delta.min)

To solve the error, import the timedelta class from the datetime module.

main.py
# ✅ Import the `timedelta` class first
from datetime import timedelta


delta = timedelta(
    days=30,
    seconds=45,
    microseconds=10,
    milliseconds=29000,
    minutes=3,
    hours=7,
    weeks=2,
)

print(delta)

print(delta.max)
print(delta.min)

Even though the datetime module is in the Python standard library, we still have to import it before using it.

Make sure you haven't misspelled timedelta in the import statement as the names of classes are case-sensitive.

Also, make sure you haven't imported timedelta in a nested scope, e.g. a function.

Import the function at the top level of the file to be able to use it throughout your code.

A timedelta object represents a duration - the difference between two dates or times.

All of the arguments we passed to the class in the example above are optional and default to 0.

You can read more about timedelta objects by visiting the official docs.

# NameError: name 're' is not defined in Python

The Python "NameError: name 're' is not defined" occurs when we use the re module without importing it first.

To solve the error, import the re module before using it - import re.

nameerror name re is not defined

Here is an example of how the error occurs.

main.py
# ⛔️ NameError: name 're' is not defined
prog = re.compile(r'\w+')

result = prog.match('hello world 123')

print(result)

# Import the re module before using it

To solve the error, we have to import the re module.

main.py
# ✅ import the `re` module first
import re

prog = re.compile(r'\w+')

result = prog.match('hello world 123')

print(result)

Even though the re module is in the Python standard library, we still have to import it before using it.

Make sure you haven't used a capital letter r when importing re because module names are case-sensitive.

# Make sure to not import the re module in a nested scope

Make sure you haven't imported re in a nested scope, e.g. a function.

main.py
def example():
    import re

    prog = re.compile(r'\w+')

    result = prog.match('hello world 123')

    print(result)


# ⛔️ NameError: name 're' is not defined
prog = re.compile(r'\w+')

We imported the re module in a function, so we aren't able to use it outside of the function.

Import the module at the top level to be able to use it throughout your code.

main.py
# ✅ import at the top level of the module
import re


def example():

    prog = re.compile(r'\w+')

    result = prog.match('hello world 123')

    print(result)


# ⛔️ NameError: name 're' is not defined
prog = re.compile(r'\w+')

The import statement for the re module has to come at the top of the file before any code that makes use of it.

# Only importing the functions you need from the re module

An alternative to importing the entire re module is to import only the functions and constants that your code uses.

main.py
# 👇️ Import only compile function from re module
from re import compile

prog = compile(r'\w+')

result = prog.match('hello world 123')

print(result)

The example shows how to only import the compile function from the re module.

Instead of accessing the members on the module, e.g. re.compile, we now access them directly.

This should be your preferred approach because it makes your code easier to read.

For example, when we use an import such as import re, it is much harder to see which functions from the re module are being used in the file.

Conversely, when we import specific functions, it is much easier to see which functions from the re module are being used.

The re module provides regular expression matching operations.

You can view all of the functions the re module provides by visiting the official docs.

# NameError: name 'csv' is not defined in Python

The Python "NameError: name 'csv' is not defined" occurs when we use the csv module without importing it first.

To solve the error, import the csv module before using it - import csv.

nameerror name csv is not defined

Here is an example of how the error occurs.

main.py
with open('employees.csv', 'w', newline='', encoding='utf-8') as csvfile:
    fieldnames = ['first_name', 'last_name']
    # ⛔️ NameError: name 'csv' is not defined
    writer = csv.DictWriter(csvfile, fieldnames=fieldnames)

    writer.writeheader()
    writer.writerow({'first_name': 'Alice', 'last_name': 'Smith'})
    writer.writerow({'first_name': 'Bob', 'last_name': 'Smith'})
    writer.writerow({'first_name': 'Carl', 'last_name': 'Smith'})

To solve the error, we have to import the csv module.

main.py
# ✅ import the `csv` module first
import csv


with open('employees.csv', 'w', newline='', encoding='utf-8') as csvfile:
    fieldnames = ['first_name', 'last_name']
    writer = csv.DictWriter(csvfile, fieldnames=fieldnames)

    writer.writeheader()
    writer.writerow({'first_name': 'Alice', 'last_name': 'Smith'})
    writer.writerow({'first_name': 'Bob', 'last_name': 'Smith'})
    writer.writerow({'first_name': 'Carl', 'last_name': 'Smith'})

Even though the csv module is in the Python standard library, we still have to import it before using it.

Make sure you haven't used a capital letter c when importing csv because module names are case-sensitive.

Also, make sure you haven't imported csv in a nested scope, e.g. a function. Import the module at the top level to be able to use it throughout your code.

An alternative to importing the entire csv module is to import only the functions and classes that your code uses.

main.py
from csv import DictWriter


with open('employees.csv', 'w', newline='', encoding='utf-8') as csvfile:
    fieldnames = ['first_name', 'last_name']
    writer = DictWriter(csvfile, fieldnames=fieldnames)

    writer.writeheader()
    writer.writerow({'first_name': 'Alice', 'last_name': 'Smith'})
    writer.writerow({'first_name': 'Bob', 'last_name': 'Smith'})
    writer.writerow({'first_name': 'Carl', 'last_name': 'Smith'})

The example shows how to import the DictWriter class from the csv module.

Instead of accessing the members on the module, e.g. csv.DictWriter, we now access them directly.

This should be your preferred approach because it makes your code easier to read.

For example, when we use an import such as import csv, it is much harder to see which classes or functions from the csv module are being used in the file.

Conversely, when we import specific classes, it is much easier to see which classes and methods from the csv module are being used.

The csv module implements classes to read and write tabular data in CSV format.

You can view all of the classes and methods the csv module provides by visiting the official docs.

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