Problem Formulation

Say, you try to import label_map_util from the utils module when running TensorFlow’s object_detection API. You get the following error message:

>>> from utils import label_map_util

Traceback (most recent call last): File "<pyshell#3>", line 1, in <module> from utils import label_map_util

ModuleNotFoundError: No module named 'utils'

Question: How to fix the ModuleNotFoundError: No module named 'utils'?

Solution Idea 1: Fix the Import Statement

The most common source of the error is that you use the expression from utils import <something> but Python doesn’t find the utils module. You can fix this by replacing the import statement with the corrected from object_detection.utils import <something>.

For example, do not use these import statements:

from utils import label_map_util
from utils import visualization_utils as vis_util

Instead, use these import statements:

from object_detection.utils import label_map_util
from object_detection.utils import visualization_utils as vis_util

Everything remains the same except the bolded text.

This, of course, assumes that Python can resolve the object_detection API. You can follow the installation recommendations here, or if you already have TensorFlow installed, check out the Object Detection API installation tips here.

Solution Idea 2: Modify System Path

Another idea to solve this issue is to append the path of the TensorFlow Object Detection API folder to the system paths so your script can find it easily.

To do this, import the sys library and run sys.path.append(my_path) on the path to the object_detection folder that may reside in /home/.../tensorflow/models/research/object_detection, depending on your environment.

import sys

sys.path.append('path/to/object/detection/folder')

Solution Idea 3: Dirty Copy and Paste

I don’t recommend using this approach but I still want to share it with you for comprehensibility. Try copying the utils folder from models/research/object_detection in the same directory as the Python file requiring utils.

Solution Idea 4: Import Module from Another Folder (Utils)

This is a better variant of the previous approach: use our in-depth guide to figure out a way to import the utils module correctly, even though it may reside on another path. This should usually do the trick.

Recommended Tutorial: How to Import a Module from Another Path

Resources: You can find more about this issue here, here, and here. Among other sources, these were also the ones that inspired the solutions provided in this tutorial.

Thanks for reading this—feel free to learn more about the benefits of a TensorFlow developer (we need to keep you motivated so you persist through the painful debugging process you’re currently in).

Recommended Tutorial: TensorFlow Developer – Income and Opportunity

Summary: Split the string using split and then use len to count the results.

Minimal Example

print("Result Count: ", len('one,two,three'.split(',')))

# Result Count: 3

Problem Formulation

Problem: Given a string. How will you split the string and find the number of split strings? Can you store the split strings into different variables?

Example

# Given String

text = '366NX-BQ62X-PQT9G-GPX4H-VT7TX'

# Expected Output:

Number of split strings: 5

key_1 = 366NX

key_2 = BQ62X

key_3 = PQT9G

key_4 = GPX4H

key_5 = VT7TX

In the above problem, the delimiter used to split the string is “-“. After splitting five substrings can be extracted. Therefore, you need five variables to store the five substrings. Can you solve it?

Solution

Splitting the string and counting the number of results is a cakewalk. All you have to do is split the string using the split() function and then use the len method upon the resultant list returned by the split method to get the number of split strings present.

Code:

text = '366NX-BQ62X-PQT9G-GPX4H-VT7TX'

# splitting the string using - as separator

res = text.split('-')

# length of split string list

x = len(res)

print("Number of split strings: ", x)

Approach 1

• The idea here is to find the length of the results and then use this length to create another list containing all the variable names as items within it. This can be done with a simple for loop.
• Now, you have two lists. One that stores the split strings and another that stores the variable names that will store the split strings.
• So, you can create a dictionary out of the two lists such that the keys in this dictionary will be the items of the list containing the variable names and the values in this dictionary will be the items of the list containing the split strings. Read: How to Convert Two Lists Into A Dictionary

Code:

text = '366NX-BQ62X-PQT9G-GPX4H-VT7TX'

# splitting the string using - as separator

res = text.split('-')

# length of split string list

x = len(res) # Naming and storing variables and values

name = []

for i in range(1, x+1): name.append('key_'+str(i)) d = dict(zip(name, res))

for key, value in d.items(): print(key, "=", value)

Approach 2

Almost all modules have a special attribute known as __dict__ which is a dictionary containing the module’s symbol table. It is essentially a dictionary or a mapping object used to store an object’s (writable) attributes.

So, you can create a class and then go ahead create an instance of this class which can be used to set different attributes. Once you split the given string and also create the list containing the variable names (as done in the previous solution), you can go ahead and zip the two lists and use the setattr() method to assign the variable and their values which will serve as the attributes of the previously created class object. Once, you have set the attributes (i.e. the variable names and their values) and attached them to the object, you can access them using the built-in __dict__ as object_name.__dict__

Code:

text = '366NX-BQ62X-PQT9G-GPX4H-VT7TX'

# splitting the string using - as separator

res = text.split('-')

# length of split string list

x = len(res)

print("Number of split strings: ", x) # variable creation and value assignment

name = []

for i in range(1, x + 1): name.append('key_' + str(i)) class Record(): pass r = Record() for name, value in zip(name, res): setattr(r, name, value)

print(r.__dict__) for key, value in r.__dict__.items(): print(key, "=", value)

Approach 3

Caution: This solution is not recommended unless this is the only option left. I have mentioned this just because it solves the purpose. However, it is certainly not the best way to approach the given problem.

Code:

text = '366NX-BQ62X-PQT9G-GPX4H-VT7TX'

# splitting the string using - as separator

res = text.split('-')

# length of split string list

x = len(res)

print("Number of split strings: ", x)

name = []

for i in range(1, x + 1): name.append('key_' + str(i)) for idx, value in enumerate(res): globals()["key_" + str(idx + 1)] = value

print(globals())

x = 0

for i in reversed(globals()): print(i, "=", globals()[i]) x = x+1 if x == 5: break

Explanation: globals() function returns a dictionary containing all the variables in the global scope with the variable names as the key and the value assigned to the variable will be the value in the dictionary. You can reference this dictionary and add new variables by string name (globals()['a'] = 'b' sets variable a equal to "b"), however this is generally a terrible thing to do.

Since global returns a dictionary containing all the variables in the global scope, a workaround to get only the variables we assigned is to extract the last “N” key-value pairs from this dictionary where “N” is the length of the split string list.

Conclusion

I hope the solutions mentioned in this tutorial have helped you. Please stay tuned and subscribe for more interesting reads and solutions in the future. Happy coding!