Use slices.Reverse in Go 1.21 or later: slices.Reverse(s) Answers for Go version 1.20 and earlier: The standard library does not have a built-in function for reversing a slice. Use a for loop to reverse a slice: for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 { s[i], s[j] = s[j], … Read more
Edit: as of Go 1.17+, you may be able to use new support for slice-to-array conversions, https://tip.golang.org/ref/spec#Conversions_from_slice_to_array_pointer: s := make([]byte, 2, 4) s0 := (*[0]byte)(s) // s0 != nil s1 := (*[1]byte)(s[1:]) // &s1[0] == &s[1] s2 := (*[2]byte)(s) // &s2[0] == &s[0] s4 := (*[4]byte)(s) // panics: len([4]byte) > len(s) Previous answer for Go … Read more
You can use list comprehension to split your dataframe into smaller dataframes contained in a list. n = 200000 #chunk row size list_df = [df[i:i+n] for i in range(0,df.shape[0],n)] Or use numpy array_split, see this comment for discrepancies: list_df = np.array_split(df, n) You can access the chunks with: list_df[0] list_df[1] etc… Then you can assemble … Read more
If you want to get n elements from the end of an array simply fetch the elements from -n to -1: PS C:\> $a = 0,1,2,3 PS C:\> $n = 2 PS C:\> $a[-$n..-1] 2 3 Edit: PowerShell doesn’t support indexing relative to both beginning and end of the array, because of the way $a[$i..$j] … Read more
You can leave one end of the slice open by not specifying the value. test[3:] = [3, 4, 5, 6, 7, 8, 9] test[:3] = [0, 1, 2]
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
The syntax is: a[start:stop] # items start through stop-1 a[start:] # items start through the rest of the array a[:stop] # items from the beginning through stop-1 a[:] # a copy of the whole array There is also the step value, which can be used with any of the above: a[start:stop:step] # start through not … Read more
How about this: in python 2.x : def slicedict(d, s): return {k:v for k,v in d.iteritems() if k.startswith(s)} In python 3.x : def slicedict(d, s): return {k:v for k,v in d.items() if k.startswith(s)}
Ruby 2.6 introduced endless ranges, which basically remove the need to have to specify the end index. In your case, you can do: s = “hello world” s[6..]
Just a different take, that only works if [[1,3,5],[2,4]] is an acceptable partition, in your example. def partition ( lst, n ): return [ lst[i::n] for i in xrange(n) ] This satisfies the example mentioned in @Daniel Stutzbach’s example: partition(range(105),10) # [[0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100], # [1, 11, … Read more