slice

Conversion of a slice of string into a slice of custom type

由 帅比萌擦擦* 提交于 2019-12-07 04:57:26
问题 I'm quite new to Go, so this might be obvious. The compiler does not allow the following code: (http://play.golang.org/p/3sTLguUG3l) package main import "fmt" type Card string type Hand []Card func NewHand(cards []Card) Hand { hand := Hand(cards) return hand } func main() { value := []string{"a", "b", "c"} firstHand := NewHand(value) fmt.Println(firstHand) } The error is: /tmp/sandbox089372356/main.go:15: cannot use value (type []string) as type []Card in argument to NewHand From the specs,

How to raise an IndexError when slice indices are out of range?

由 允我心安 提交于 2019-12-07 03:52:27
问题 The Python Documentation states that slice indices are silently truncated to fall in the allowed range and therefor no IndexErrors are risen when slicing a list, regardless what start or stop parameters are used: >>> egg = [1, "foo", list()] >>> egg[5:10] [] Since the list egg does not contain any indices greater then 2 , a egg[5] or egg[10] call would raise an IndexError : >> egg[5] Traceback (most recent call last): IndexError: list index out of range The question is now, how can we raise

How do I process a range in slices in Rust?

由 微笑、不失礼 提交于 2019-12-07 03:24:09
问题 I understand that the preferred way to iterate in Rust is through the for var in (range) syntax, but sometimes I'd like to work on more than one of the elements in that range at a time. From a Ruby perspective, I'm trying to find a way of doing (1..100).each_slice(5) do |this_slice| in Rust. I'm trying things like for mut segment_start in (segment_size..max_val).step_by(segment_size) { let this_segment = segment_start..(segment_start + segment_size).iter().take(segment_size); } but I keep

pandas mix position and label indexing without chaining

由 久未见 提交于 2019-12-07 02:47:03
问题 Since .ix has been deprecated as of Pandas 0.20, I wonder what is the proper way to mix lable-based, boolean-based and position-based indexing in Pandas? I need to assign values to a slice of dataframe that can be best referenced with label or boolean on the index and position on the columns. For example (using .loc as placeholder for the desired slicing method): df.loc[df['a'] == 'x', -12:-1] = 3 obviously this doesn't work, with which I get: TypeError: cannot do slice indexing on <class

How do you reference Array.prototype.slice.call()?

由 家住魔仙堡 提交于 2019-12-07 01:20:01
问题 I am writing a script in which I need to clone arrays in many different places. For this reason, I would like to do the following to emulate a cloning function: var clone = [].slice.call; var arr1 = [1,2,3,4,5,6,7,8,9,10]; var arr2 = clone(arr1, 0); Unfortunately, the above code results in: TypeError: object is not a function . I realize there are many functions out there to do deep cloning and shallow copies but I just want to use the built in method. Interestingly enough, the following does

Convert []interface to []string in Golang

由 你离开我真会死。 提交于 2019-12-07 00:37:23
问题 I'm using the github.com/fatih/structs package to convert values of all fields of a struct into []interface{} with the toValues() function. See here. This works fine, but eventually I want to write the values to a csv file by using the csv package. The csv.Write() function requires []string as input. So in short: how can I easily convert the output of toValues() into an array of strings? 回答1: You can't simply convert []interface{} to []string even if all the values are of concrete type string

Python Slicing 'bob' in s [duplicate]

由 匆匆过客 提交于 2019-12-07 00:30:06
This question already has answers here : String count with overlapping occurrences (23 answers) Closed 6 years ago . s = 'gfdhbobobyui' bob = 0 for x in range(len(s)): if x == 'bob': bob += 1 print('Number of times bob occurs is: ' + str(bob)) Attempting to write a code that will count the amount of times 'bob' appears in s, but for some reason this always outputs 0 for number of 'bob'. Here, try this, handcrafted :) for i, _ in enumerate(s): #i here is the index, equal to "i in range(len(s))" if s[i:i+3] == 'bob': #Check the current char + the next three chars. bob += 1 print('Number of times

how to split the array in to two equal parts using php

由 梦想的初衷 提交于 2019-12-06 23:00:29
问题 how to split an array in to two equal parts using array_slice() in PHP ? This is my requirement: First array contains: 0-1200 Second array contains: 1200-end 回答1: From the documentation for array_slice, all you have to do is give array_slice an offset and a length. In your case: $firsthalf = array_slice($original, 0, 1200); $secondhalf = array_slice($original, 1200); In other words, this code is telling array_slice : take the first 1200 records; then, take all the records starting at index

Slicing a Pandas DataFrame into a new DataFrame

由 不打扰是莪最后的温柔 提交于 2019-12-06 20:11:59
问题 I would like to slice a DataFrame with a Boolean index obtaining a copy, and then do stuff on that copy independently of the original DataFrame. Judging from this answer, selecting with .loc using a Boolean array will hand me back a copy, but then, if I try to change the copy, SettingWithCopyWarning gets in the way. Would this then be the correct way: import numpy as np import pandas as pd d1 = pd.DataFrame(np.random.randn(10, 5), columns=['a', 'b', 'c', 'd', 'e']) # create a new dataframe

Decreasing slice capacity

由 本秂侑毒 提交于 2019-12-06 17:29:19
问题 My question is about slice length and capacity. I'm learning about Go here: https://tour.golang.org/moretypes/11. (My question was marked as a possible duplicate of this; however, this is not the case. My question is specifically about the cutting off the first few elements of a slice and the implications of that.) Why does the line s = s[2:] decrease the capacity when s = s[:4] and s = s[:0] do not? The only difference I see is that there is a number before the colon in s = s[2:] while there
订阅 slice