for-loop

问题 I am sorry if this doesn't really belong here but I'm looking for a way to describe the mathematical background of my code. Using numpy I sum two more dimensional arrays: a.shape = (10, 5, 2) b.shape = (5, 2) c = a + b c.shape = (10, 5, 2) Is there a pure mathematical notation for this (so WITHOUT indroducing for-loops or numpy conventions in my text)? What I'm trying to avoid is to have to write something like this: c_{1, y, z} = a_{1, y, z} + b_{y, z} c_{2, y, z} = a_{2, y, z} + b_{y, z} ..

问题 In my Python 3(.5) script I have a simple for loop, that looks like this: request = "simple string" ignore = ( # Tuple that contains regex's to ignore ) for (i, regex) in enumerate(ignore): if re.search(regex, request): print("Found regex {0}.".format(i)) return False Now, this works as expected and the loop stops on the first match that is found. I understand that the break statement is what is used to break loops in Python. Knowing this lead to the question: Must I use the break statement

问题 I know we can loop through columns in VBA by doing this: For j = 3 To 6 but I want to loop through specific columns only, say For j = 3, 5, 6, 7 , 8, 9 to 12 but this does not seem workable. Does anyone have any idea how I could achieve this outcome? Thank you in advance! Update: The code for the workbook, I changed the part where to Mikku's suggestion to loop through the columns. So I changed it to this: Private Function MissingEntries() As Boolean Dim i As Integer Dim atLeastOneLine As

问题 I know we can loop through columns in VBA by doing this: For j = 3 To 6 but I want to loop through specific columns only, say For j = 3, 5, 6, 7 , 8, 9 to 12 but this does not seem workable. Does anyone have any idea how I could achieve this outcome? Thank you in advance! Update: The code for the workbook, I changed the part where to Mikku's suggestion to loop through the columns. So I changed it to this: Private Function MissingEntries() As Boolean Dim i As Integer Dim atLeastOneLine As

问题 So I'm working on a Windows Batch script and I want to know if an input string (the name of a file) is exactly four letters long. I want to do it with regular expressions or string matching. I tried the following but it didn't work... for /R "%windir%\system32" %%f in (*) do ( set filename=%%~nf if not "!filename!"=="!filename:[a-z][a-z][a-z][a-z]=!" ( echo %%~nf ) ) So my code loops through all the files in \system32. The files like mode.com should be echoed, but it's not the case. 回答1: This

问题 I tried: let mut vec = [1,2,3]; for mut x in &vec { *x=3; } for mut &x in &vec { x=3; } for mut *x in &vec { x=3; } for mut x in mut &vec { *x=3; } for mut x in &(mut vec) { *x=3; } None of these work; how should I do it? 回答1: You may want to re-read The Rust Programming Language section on mutability: You can also create a reference to it, using &x , but if you want to use the reference to change it, you will need a mutable reference: let mut x = 5; let y = &mut x; fn main() { let mut array

问题 I want to produce a pdf which shows multiple graphs, one for each NetworkTrackingPixelId . I have a data frame similar to this: > head(data) NetworkTrackingPixelId Name Date Impressions 1 2421 Rubicon RTB 2014-02-16 168801 2 2615 Google RTB 2014-02-16 1215235 3 3366 OpenX RTB 2014-02-16 104419 4 3606 AppNexus RTB 2014-02-16 170757 5 3947 Pubmatic RTB 2014-02-16 68690 6 4299 Improve Digital RTB 2014-02-16 701 I was thinking to use a script similar to the one below: # create a vector which

问题 int i,j; for(i=0;j=10;j>=0;i<10;i++;j--){ printf("%d %d",i,j); } It brings error while executing, how to rectify it and what is the correct syntax for using multiple iterators in for loop 回答1: A for loop has the following syntax: for ( expression ; expression ; expression ) There are 3 expressions separated by semicolons. You have 6 expressions separated by semicolons. That's invalid syntax. You should write it as follows: for(i=0,j=10; j>=0 && i<10; i++,j--) For the first expression,

问题 int i,j; for(i=0;j=10;j>=0;i<10;i++;j--){ printf("%d %d",i,j); } It brings error while executing, how to rectify it and what is the correct syntax for using multiple iterators in for loop 回答1: A for loop has the following syntax: for ( expression ; expression ; expression ) There are 3 expressions separated by semicolons. You have 6 expressions separated by semicolons. That's invalid syntax. You should write it as follows: for(i=0,j=10; j>=0 && i<10; i++,j--) For the first expression,

问题 I have an array with say 400 (but could be anything) names i want to send to an API, but the API only receives a max of 200 requests per time, how do i chunk my array so that for every 200th item, i perform an action? Here's what i have so far, rather than making my API request, i'm just trying to output the array's to the page. <?php for ($i = 0; $i <= $smsListLimit; $i++) { if ($i <= 199) { array_push($newarray, $smsList[$i]); if ($i == 199) { echo “ < pre > “; var_dump($newarray); echo “ <