What does [:-1] mean/do in python? - Stack Overflow

Working on a python assignment and was curious as to what [:-1] means in the context of the following code: instructions = f.readline()[:-1] Have searched on here on S.O. and on Google but to no avail. Would love an explanation!

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Python Slicing – How to Slice an Array and What Does [::-1] Mean?

Here, we specify a start of index 2, no end, and a step of -1. Slicing here will start from index 2 which is 3. The negative steps mean the next value in the slice will be at an index smaller than the previous index by 1. This means 2 - 1 which is 1 so the value at this index, which is 2 will be added to the slice.

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list - what does [::-1] mean in python - slicing? - Stack Overflow

Slicing. Negative numbers for start and stop mean "from the end". It's essianlly equivalent of len-value.; Negative number for step means "in reverse order".; Empty start means 0 i.e. 1st element. Empty stop means len.Stop parameter is exclusive!

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python - What does [:] mean? - Stack Overflow

[1:5] for displaying values between 1 inclusive and 5 exclusive i.e 1-4 [start:end] basically used in array for slicing , understand bracket accept variable that mean value or key to display, and " : " is used to limit or slice the entire array into packets .

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What Does 'do' Do in Python - Online Tutorials Library

Slicing in Python gets a sub-string from a string. The slicing range is set as parameters i.e. start, stop and step. For slicing, the 1st index is 0.

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Python String question: What does [::-1] mean? - Sololearn

In Python, the syntax `[::-1]` is used to reverse a string. It is known as string slicing with a step value of -1. It is known as string slicing with a step value of -1. Let's break down how it works: - The first colon `:` indicates that we want to slice the entire string.

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Python Operators - W3Schools

Sets each bit to 1 if both bits are 1: x & y: Try it » | OR: Sets each bit to 1 if one of two bits is 1: x | y: Try it » ^ XOR: Sets each bit to 1 if only one of two bits is 1: x ^ y: Try it » ~ NOT: Inverts all the bits ~x: Try it » << Zero fill left shift: Shift left by pushing zeros in from the right and let the leftmost bits fall off: x ...

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The += Operator In Python - A Complete Guide - AskPython

Congratulations! You just learned about the ‘+=’ operator in python and also learned about its various implementations. Liked the tutorial? In any case, I would recommend you to have a look at the tutorials mentioned below: The “in” and “not in” operators in Python; Python // operator – Floor Based Division; Python Not Equal operator

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What does -1 mean in numpy reshape? - GeeksforGeeks

Hence, we can see that we can not pass -1 to more than one. Traceback (most recent call last): File "main.py", line 3, in <module> newarr = arr.reshape(2, -1, -1) ValueError: can only specify one unknown dimension. Flattening the Numpy arrays. Flattening an array means converting an array to a 1D array. We can use reshape(-1) to do this. Example 1

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numpy - what does [:, :, ::-1] mean in python? - Stack Overflow

This is numpy-specific and will not work for most python objects. The : means "take everything in this dimension" and the ::-1 means "take everything in this dimension but backwards." Your matrix has three dimensions: height, width and color. Here you're flipping the color from BGR to RGB.

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