slice

问题 I have a slice that I want to change (for example i want to remove the first element) using a function. I thought to use a pointer, but I still can't index it. What am I doing wrong? Playground link: func change(list *[]int) { fmt.Println(*list) *list = *list[1:] //This line screws everything up } var list = []int{1, 2, 3} func main() { change(&list) } 回答1: You need to use (*list) . func change(list *[]int) { *list = (*list)[1:] } or a different approach that's usually more go idomatic: func

问题 Anyone care to take a stab at speeding up this dataframe index slicing scheme? I'm trying to slice and dice some huge dataframes, so every bit counts. I need to somehow find a faster way of index slicing the dataframe, other than the following technique: v = initFrame.xs(x,level=('ifoo2','ifoo3'), drop_level=False) Also the loop in pd.unique is impacting performance pretty significantly. uniqueList = list(pd.unique(initFrame[['bar1','bar4']].values)) Copy and paste the below snippet to avoid

问题 My code looks like: d = pd.read_csv('Collector Output.csv') df = pd.DataFrame(data=d) dfa = df.copy() dfa = dfa.rename(columns={'OBJECTID': 'Object ID', 'test_no': 'TEST #', 'retest_no': 'RETEST #', 'tester': 'TESTED BY', 'date': 'DATE', 'proj_no': 'Project Number', 'test_elev': 'TEST ELEVATION', 'curve_no': 'CURVE #', 'curve': 'Curve Description', 'dry': 'Dry Maximum Density (pcf)', 'opt': 'OPT. M.C.', 'Material Type': 'Material Type', 'AC Thickness': 'AC Thickness', 'AB Thickness': 'AB

问题 I draw PieChart with 4 slices in iPhone app. I want to add Names in each Slice in Pie Chart. Am using Core-Plot9. And also i want to give different colors for each slice in PieChart. How can do this? Please suggest me any idea/sample code to do this. Please help me. Thanks in advance. 回答1: download the samples from given link then go to CorePlot_0.9->Source->examples->CPTTestApp-iPhone check this sample. it will give you an idea how to solve your problem? core plot example 来源： https:/

问题 I passed a reference of a slice to a function and I am making changes in the slice inside the function. Also I am trying to access an element from the slice using index. It is throwing exception in golang. What is the best way to access an element from a slice by index which is passed by reference? You can find a sample code here. [ref : http://www.reddit.com/r/golang/comments/283vpk/help_with_slices_and_passbyreference/ ]. Since my code is huge I added a sample. package main import "fmt"

问题 Here is my query : c := session.DB("searchV").C("video") var results []BadVideo err5 := c.Find(nil).All(&results) fmt.Println("request done") if err5 != nil { panic(err5) } var i = 0 for _,badvideo := range results { } I would like to randomize the order of browsing the items of the query for making operation on each item of the request ... So each time I run it, I browse it in a different order. 回答1: Manual shuffling Here's a simple shuffle algorithm, which shuffles (randomizes) a []BadVido

问题 Say I have a list of lists >>> s = [ [1,2], [3,4], [5,6] ] I can access the items of the second list: >>> s[1][0] 3 >>> s[1][1] 4 And the whole second list as: >>> s[1][:] [3, 4] But why does the following give me the second list as well? >>> s[:][1] [3, 4] I thought it would give me the second item from each of the three lists. One can use list comprehension to achieve this (as in question 13380993), but I'm curious how to properly understand s[:][1] . 回答1: s[:] returns a copy of a list. The

问题 When reading up on Go slices, I came across this behaviour in the context of the append method If the backing array of s is too small to fit all the given values a bigger array will be allocated. The returned slice will point to the newly allocated array. Source - Golang Tour To understand this I wrote the following piece of code: Try on the Go Playground func makeSlices() { var a []int; a = append(a, 0) b := append(a, 1) printSlice("b", b) c := append(a, 2) printSlice("b", b) printSlice("c",

问题 I have several one dimensional numpy array (around 5 millions elements) I have to slice them repeatedly with the same slice. I have a a collections of arrays (all of the same dimensions ) and I want to slice them with the same array index (same dimension of the arrays) Is there a way to cal A[index] for all the different arrays A which is more efficient than the naive way? Maybe there’s a way to use Cython to speed things up? Thank you! Edit To make things clearer, this is my setting: I have

问题 I am trying to get the text selection within a an html element and then insert span tags around it. So far, I am having problems with the correct indices. If I highlight text inside a <p> block, the index goes to 0 after a <br> tag. I want to be able to slice() the text out and then recombine it with span tags after highlighting the text as well as grabbing the selected text and sending it to server via Ajax. Here is some sample HTML and code: <html><body><p>This is some sample text.<br