Python | First occurrence of True number
Many times we require to find the first occurring non-zero number to begin the processing with. This has mostly use case in Machine Learning domain in which we require to process data excluding None or 0 values. Let’s discuss certain ways in which this can be performed.
Method #1 : Using next() + enumerate()
The next function can be used to iterate through the list and enumerate along with it checks for the list if the number is a non zero element and returns the number of 0s before a True value i.e a non zero value.
# Python3 code to demonstrate # finding first True value # using next() and enumerate() # initializing list test_list = [ 0, 0, 5, 6, 0] # printing original list print ("The original list is : " + str(test_list)) # finding first True value # using next() and enumerate() res = next((i for i, j in enumerate(test_list) if j), None) # printing result print ("The values till first True value : " + str(res)) |
chevron_right
filter_none
Output:
The original list is : [0, 0, 5, 6, 0] The values till first True value : 2
Method #2 : Using filter() + lamda + index()
Using the combination of the above functions, one can easily perform this particular task. The filter function can be used to screen out the True value that is processed by the lambda functions and index function returns the first occurrence of this.
# Python3 code to demonstrate # finding first True value # using filter() + lamda + index() # initializing list test_list = [ 0, 0, 5, 6, 0] # printing original list print ("The original list is : " + str(test_list)) # finding first True value # using filter() + lamda + index() res = test_list.index(next(filter(lambda i: i != 0, test_list))) # printing result print ("The values till first True value : " + str(res)) |
chevron_right
filter_none
Output:
The original list is : [0, 0, 5, 6, 0] The values till first True value : 2
Recommended Posts:
- Python | Add the occurrence of each number as sublists
- Python | Get indices of True values in a binary list
- Python | Last occurrence of some element in a list
- Python | Percentage occurrence at index
- Python program to remove Nth occurrence of the given word
- Python | Sort tuple based on occurrence of first element
- Python | Replace multiple occurrence of character by single
- Python | Count occurrence of all elements of list in a tuple
- Python | Element Occurrence in dictionary of list values
- Generate two output strings depending upon occurrence of character in input string in Python
- Python | Count tuples occurrence in list of tuples
- Python | Find the Number Occurring Odd Number of Times using Lambda expression and reduce function
- Python Program to Find the Number Occurring Odd Number of Times
- Python Program for How to check if a given number is Fibonacci number?
- 21 Number game in Python
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.
