Python reverse-stride slicing
Simply exclude the end range index… >>> foo[3::-1] ‘3210’ Ironically, about the only option I think you didn’t try.
slice
Insert element in Python list after every nth element
I’ve got two one liners. Given: >>> letters = [‘a’,’b’,’c’,’d’,’e’,’f’,’g’,’h’,’i’,’j’] Use enumerate to get index, add ‘x’ every 3rd letter, eg: mod(n, 3) == 2, then concatenate into string and list() it. >>> list(”.join(l + ‘x’ * (n % 3 == 2) for n, l in enumerate(letters))) [‘a’, ‘b’, ‘c’, ‘x’, ‘d’, ‘e’, ‘f’, ‘x’, … Read more
How to preallocate and fill a slice of pointers in a go-idiomatic way?
For your first example, I would do: mySlice := make([]*UselessStruct, 5) for i := range mySlice { mySlice[i] = new(UselessStruct) } The issue you are facing in both examples is you are appending to a slice that is already the correct length. If you set mySlice := make([]*UselessStruct, 5), you are asking for a slice … Read more
Why does foo[‘bar’: ‘baz’] raise TypeError rather than SyntaxError?
Using the colon in an indexing operation generates a slice object, which is not hashable.
How to remove all element from array except the first one in javascript
You can set the length property of the array. var input = [‘a’,’b’,’c’,’d’,’e’,’f’]; input.length = 1; console.log(input); OR, Use splice(startIndex) method var input = [‘a’,’b’,’c’,’d’,’e’,’f’]; input.splice(1); console.log(input); OR use Array.slice method var input = [‘a’,’b’,’c’,’d’,’e’,’f’]; var output = input.slice(0, 1) // 0-startIndex, 1 – endIndex console.log(output);
Difference between list, sequence and slice in Python?
You’re mixing very different things in your question, so I’ll just answer a different question You are now asking about one of the most important interface in Python: iterable – it’s basically anything you can use like for elem in iterable. iterable has three descendants: sequence, generator and mapping. A sequence is a iterable with … Read more
resize with averaging or rebin a numpy 2d array
Here’s an example based on the answer you’ve linked (for clarity): >>> import numpy as np >>> a = np.arange(24).reshape((4,6)) >>> a array([[ 0, 1, 2, 3, 4, 5], [ 6, 7, 8, 9, 10, 11], [12, 13, 14, 15, 16, 17], [18, 19, 20, 21, 22, 23]]) >>> a.reshape((2,a.shape[0]//2,3,-1)).mean(axis=3).mean(1) array([[ 3.5, 5.5, 7.5], [ … Read more
Check whether a string slice contains a certain value in Go
If you have a slice of strings in an arbitrary order, finding if a value exists in the slice requires O(n) time. This applies to all languages. If you intend to do a search over and over again, you can use other data structures to make lookups faster. However, building these structures require at least … Read more
Understanding string reversal via slicing
Sure, the [::] is the extended slice operator. It allows you to take substrings. Basically, it works by specifying which elements you want as [begin:end:step], and it works for all sequences. Two neat things about it: You can omit one or more of the elements and it does “the right thing” Negative numbers for begin, … Read more
Iteration over list slices
If you want to divide a list into slices you can use this trick: list_of_slices = zip(*(iter(the_list),) * slice_size) For example >>> zip(*(iter(range(10)),) * 3) [(0, 1, 2), (3, 4, 5), (6, 7, 8)] If the number of items is not dividable by the slice size and you want to pad the list with None … Read more