subtraction

问题 i am working on frames of a video and i want to subtract one frame from other to find out the difference but i dont know how to proceed. i tried converting my bitmap frames into mat and then subtracting them but its not working. i am using opencv 2.4.3 for mat function. can anybody tell me how to do that. if possible explain with code snippets. i tried something like this Bitmap myBitmap1 = BitmapFactory.decodeFile("/mnt/sdcard/Frames/mpgFrames/image001.jpg"); Bitmap myBitmap2 = BitmapFactory

问题 I have some CGPath (a poly with two circle) carried out on a CAShapeLayer . Can I trim/subtract paths like this? 回答1: Instead of do the math, the result can be achieved at drawing time using kCGBlendModeClear . // Create the poly. CGContextBeginPath(context); CGContextMoveToPoint (context, a_.x, a_.y); CGContextAddLineToPoint (context, b_.x, b_.y); CGContextAddLineToPoint (context, c_.x, c_.y); CGContextAddLineToPoint (context, d_.x, d_.y); CGContextClosePath(context); // Draw with the

问题 Basically, the behavior you get when overflowing integers with subtraction, but for a given number of bits. The obvious way, assuming a signed integer: template <int BITS> int sub_wrap(int v, int s) { int max = (1<<(BITS)); v -= s; if (v < -max) v += max*2; // or if branching is bad, something like: // v += (max*2) * (v < -max) return v; } // For example subtracting 24 from -16 with 5 bit wrap, // with a range of -32, 31 sub_wrap<5>(-16, 28); -> 20 Is there a neat way of doing it that is less

问题 I have been looking for an answer for a few hours now, but I can't find one. I'm writing a simple script . The user sets their work start and end time. So, for example, somebody is working from 8:00 to 16:00. How can I subtract this time to see how long the person has been working? I was experimenting with strtotime(); but without success... 回答1: A bit nicer is the following: $a = new DateTime('08:00'); $b = new DateTime('16:00'); $interval = $a->diff($b); echo $interval->format("%H"); That

问题 I need to subtract all elements in one column of pandas dataframe by its first value. In this code, pandas complains about self.inferred_type, which I guess is the circular referencing. df.Time = df.Time - df.Time[0] And in this code, pandas complains about setting value on copies. df.Time = df.Time - df.iat[0,0] What is the correct way to do this computation in Pandas? 回答1: I think you can select first item in column Time by iloc: df.Time = df.Time - df.Time.iloc[0] Sample: start = pd.to

问题 I have 2 pandas dataframes. A = pd.DataFrame({'c1':[1],'c2':[2],'c3':[2],'c4':[1],'c5':[1],'c6':[1]}) B = pd.DataFrame({'c1':[0],'c2':[1],'c3':[0],'c4':[1],'c5':[0],'c6':[1]}) I would like to subtract B to A and assign the difference to A. I tried several options wither using the assign subtraction or pandas subtraction functions, but don't seem to get the right values. Either get "NaN" when subtracting and assigning or the wrong data. I tried: A.sub(B, fill_value=0) and A-=B I expect, after

问题 I have 2 pandas dataframes. A = pd.DataFrame({'c1':[1],'c2':[2],'c3':[2],'c4':[1],'c5':[1],'c6':[1]}) B = pd.DataFrame({'c1':[0],'c2':[1],'c3':[0],'c4':[1],'c5':[0],'c6':[1]}) I would like to subtract B to A and assign the difference to A. I tried several options wither using the assign subtraction or pandas subtraction functions, but don't seem to get the right values. Either get "NaN" when subtracting and assigning or the wrong data. I tried: A.sub(B, fill_value=0) and A-=B I expect, after

问题 I'm trying to subtract two dates and expecting some floating values return. But what I got in return is as below: +000000000 00:00:07.225000 Multiplying the value by 86400 (I want to get the difference in second) is getting something even more strange value being returned: +000000007 05:24:00.000000000 any idea? I'm suspecting is has something to do with type casting. 回答1: I guess your columns are defined as timestamp rather than date . The result of subtracting timestamps is an interval

问题 I am using this script from snipplr, How would I set it so the container div is 100px less than the newWindowHeight height, like -100 or something. <script type="text/javascript" charset="utf-8"> $(document).ready(function(){ //If the User resizes the window, adjust the #container height $(window).bind("resize", resizeWindow); function resizeWindow( e ) { var newWindowHeight = $(window).height(); $("#container").css("max-height", newWindowHeight ); } }); </script> 回答1: The script you found

问题 How to remove a pandas dataframe from another dataframe, just like the set subtraction: a=[1,2,3,4,5] b=[1,5] a-b=[2,3,4] And now we have two pandas dataframe, how to remove df2 from df1: In [5]: df1=pd.DataFrame([[1,2],[3,4],[5,6]],columns=['a','b']) In [6]: df1 Out[6]: a b 0 1 2 1 3 4 2 5 6 In [9]: df2=pd.DataFrame([[1,2],[5,6]],columns=['a','b']) In [10]: df2 Out[10]: a b 0 1 2 1 5 6 Then we expect df1-df2 result will be: In [14]: df Out[14]: a b 0 3 4 How to do it? Thank you. 回答1: