It is being used to extract a specific column from a 2D array. So your example would extract column 0 (the first column) from the first 2048 rows (0 to 2047). Note however that this syntax will only work for numpy arrays and not general python lists.
There is no sparse slices in Go, so you could simply check the length: if len(mySlice) > 3 { // … } If the length is greater than 3, you know that the index 3 and all those before that exist.
Use a slice composite literal: []int{1}, For example: package main import ( “fmt” ) func main() { var x []int for i := 2; i < 10; i += 2 { x = append(x, i) } fmt.Println(x) x = append([]int{1}, x…) fmt.Println(x) } Playground: https://play.golang.org/p/Yc87gO7gJlD Output: [2 4 6 8] [1 2 4 6 8] … Read more
Yes but you have to use a different syntax. oneSlice := []int{1, 1, 1, 1, 1} It’s referred to as ‘composite literal’ Also, if there is reason to iterate (like calculating the values based loop variable or something) then you could use the range keyword rather than the old school for i is equal to, … Read more
You create a slice by calling slice with the same fields you would use if doing [start:end:step] notation: sl = slice(0,4) To use the slice, just pass it as if it were the index into a list or string: >>> s = “ABCDEFGHIJKL” >>> sl = slice(0,4) >>> print(s[sl]) ‘ABCD’ Let’s say you have a … Read more
To query the df by the MultiIndex values, for example where (A > 1.7) and (B < 666): In [536]: result_df = df.loc[(df.index.get_level_values(‘A’) > 1.7) & (df.index.get_level_values(‘B’) < 666)] In [537]: result_df Out[537]: C A B 3.3 222 43 333 59 5.5 333 56 Hence, to get for example the ‘A’ index values, if still … Read more
The slice points into the array. No point making another array when the array already exists and the slice can just describe the desired part of it. The addition causes implicit coercion, so it works. To make your assignment work, you would need to coerce: var list = [“hello”, “world”] var slice: Array<String> = Array(list[0..<list.count])
http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.head.html?highlight=head#pandas.DataFrame.head df2 = df.head(10) should do the trick
Just got curious about this myself. Ran some benchmarks: type MyStruct struct { F1, F2, F3, F4, F5, F6, F7 string I1, I2, I3, I4, I5, I6, I7 int64 } func BenchmarkAppendingStructs(b *testing.B) { var s []MyStruct for i := 0; i < b.N; i++ { s = append(s, MyStruct{}) } } func BenchmarkAppendingPointers(b *testing.B) … Read more
One way: some_list[::len(some_list)-1] A better way (Doesn’t use slicing, but is easier to read): [some_list[0], some_list[-1]]