for-loop

问题 I'm new enough to postgresql, and I'm having issues updating a column of null values in a table using a for loop. The table i'm working on is huge so for brevity i'll give a smaller example which should get the point across. Take the following table +----+----------+----------+ | id | A | B | C | +----+----------+----------+ | a | 1 | 0 | NULL | | b | 1 | 1 | NULL | | c | 2 | 4 | NULL | | a | 3 | 2 | NULL | | c | 2 | 3 | NULL | | d | 4 | 2 | NULL | +----+----------+----------+ I want to write

问题 I'm facing a fatal error while I'm trying to manipulate a huge array of arrays in PHP and return the result as a response of an HTTP POST request : Allowed memory size of 536870912 bytes exhausted I have already tried to set ini_set('memory_limit', '-1'); in order to see if I get the result, but I didn't get any type of response. Postman crashed all the times that I tried to make the POST request. The starting structure of the array is this one. The body size is around 25mb. The main array

问题 I have a multiple standard text files that follow this format, with varying numbers of lines in each file: Line1 Line2 Line3 Line4 I want to merge every line into one, with a space in between each set of characters, so the text file would look as such: Line1 Line2 Line3 Line3 ...and so on. This needs to work with any given number of lines, due to the fact that each text file contains a different number of lines. My intention is not to merge the lines in the text files; I want each text file

问题 I have a small debate at work: Is it a good practice to calculate the size of the Array in swift before running over it's items? What would be a better code practice: Option A: func setAllToFalse() { for (var i = 0; i < mKeyboardTypesArray.count; i++ ) { self.mKeyboardTypesArray[i] = false } } or Option B: func setAllToFalse() { let typesCount = mKeyboardTypesArray.count for (var i = 0; i < typesCount; i++ ) { self.mKeyboardTypesArray[i] = false } } All, of course, if I don't alter the Array

问题 I have a huge file where I want to create a column based on other columns. My file look like this: person = c(1,2,3,4,5,6,7,8) father = c(0,0,1,1,4,5,5,7) mother = c(0,0,2,3,2,2,6,6) ped = data.frame(person,father,mother) And I want to create a column indicating if the person is a father or mother (gender column). I got it using a for loop in a small example, but when I apply in the whole file it takes hours to finish. How can I create an apply function to solve that, please. Thanks. for(i in

问题 I want to write a loop in R to run multiple regressions with one dependent variables and two lists of independent variables (all continuous variables). The model is additive and the loop should run by iterating through the two lists of variables so that it takes the first column from the first list + the first column from the second list, then the same for the second column in the two lists etc. The problem is I can't get it to iterate through the lists properly, instead my loop runs more

问题 I am working with the following data in R: > str(df) 'data.frame': 369269 obs. of 12 variables: $ bkod : int 110006 110006 110006 110006 110006 110006 110006 110006 110006 110006 ... $ bad : Factor w/ 215 levels "4. Levent","500 Evler",..: 26 26 26 26 26 26 26 26 26 26 ... $ mkod : int 359 359 359 359 359 359 359 359 359 359 ... $ mad : Factor w/ 8643 levels " Hilal Gida ",..: 4021 4021 4021 4021 4021 4021 4021 4021 4021 4021 ... $ yekod: int 12 12 12 12 12 12 12 12 12 12 ... $ yad : Factor w

问题 we can make dropdown list in asp.net component with below syntax <asp:DropDownList ID="test" runat="server"> <asp:ListItem Text="1" Value="1"></asp:ListItem> </asp:DropDownList> if we want our combo box contain 1 to 1000 , is there any way to populate it with foreach loop , rather than manually add 1000 item to it ? 回答1: Yes, you can add ListItems programmatically: for(int i=1; i<=1000; i++) { ListItem item = new ListItem(i.ToString(), i.ToString()); test.Items.Add(item); } ListItemCollection

问题 I'm writing a program that finds passwords. I ran into a problem when I saw that the "for" loops to replace parts of the password would have to be repeated for the variable of the chosen password length. The goal of this program is to generate and check a password of any character array, starting with "0" and going through "? (n times)", where '0' is the first character and '?' is the last character. Is there any way to repeat a for loop a variable number of times without coding them in

问题 SO, I am searching for a way to loop through a list of items in a for loop fashion, except I want the loop to iterate in a 'random' way. i.e. I dont want the loop to go 0,1,2,3,m+1...n, I want it to pick it in some random order and still run through the loop for all items. Here is my current looping code: for singleSelectedItem in listOfItems: item = singleSelectedItem.databaseitem logging.info(str(item)) please let me know if this doesnt make sense ;) 回答1: If listOfItems can be shuffled,