average

问题 I'm trying to make something like a chart list and my actual query is like this: SELECT user.username, songs.*, albums.desc, albums.release, albums.name, AVG(songrating.rating) FROM songs INNER JOIN user ON songs.userid=user.id INNER JOIN albums ON songs.albumid=albums.id INNER JOIN songrating ON songs.id=songrating.songid GROUP BY songrating.songid it only shows entries with at least one rating entry, but I also want these without a rating I tried to use it with if / case but it doesn't work

问题 I'm trying to make something like a chart list and my actual query is like this: SELECT user.username, songs.*, albums.desc, albums.release, albums.name, AVG(songrating.rating) FROM songs INNER JOIN user ON songs.userid=user.id INNER JOIN albums ON songs.albumid=albums.id INNER JOIN songrating ON songs.id=songrating.songid GROUP BY songrating.songid it only shows entries with at least one rating entry, but I also want these without a rating I tried to use it with if / case but it doesn't work

问题 Basically, this question is an extension of this one: Create monthly mean by time intervals Now I have temperature observations from five different sources, and I would like to apply the same logic on all of them: calculate a data interval average for each of the columns (except for the last, which should be kept untouched). First, what I need to do is to average all januaries, februaries, marches and etc for the whole period. Then, I would like to do the same for specific periods of time (3

问题 I have 2 columns, qty_req and qty_issued in a report. I need to find the average of the values in the qty_issued column. The problem is that sometimes the corresponding value of qty_req is 0. I need to take the average of the qty_issued column for only the rows where qty_req is NOT 0. How do I do this? Spun off from my other question here: MS Access: How can I average a list of quantities on a report where the quantities are not zero? 回答1: If you want to do that in the Control Source of a

问题 I have a big data set which could be represented something like this: plot 1 2 3 3 3 4 4 5 5 5 5 6 7 fate S M S S M S S S M S S M M where plot is a location, and fate is either "survivorship" or "mortality" ( a plant lives or dies.) The plot number of a plant corresponds to the fate under it. Thus in plot 5 there are 4 plants. 3 of them survive, 1 dies. I want to figure out a way to make R calculate the fraction of individuals that survive in each plot for all of these. It is proving very

问题 I have a piece of code that checks if the given 3 coordinates are linear to one another (if so, return true). But is there a way to make the code give or take a few pixels/plots? private boolean collinear(double x1, double y1, double x2, double y2, double x3, double y3) { return (y1 - y2) * (x1 - x3) == (y1 - y3) * (x1 - x2); } You see, the coordinates have to be exactly inline for it to register as linear. How will I be able to make it look within a 'range' of some kind, for it to check

问题 I find this very weird. Can someone tell me whats going on here? >>>a = [1,0,1] >>>np.mean(a) 0.66666666666666663 >>>2.0/3 0.6666666666666666 What's up with the 3 in the end of the output of np.mean(a) ? Why isn't it a 6 like the line below it or a 7(when rounding off)? 回答1: This is just a case of a different string representation of two different types: In [17]: a = [1, 0, 1] In [18]: mean(a) Out[18]: 0.66666666666666663 In [19]: type(mean(a)) Out[19]: numpy.float64 In [20]: 2.0 / 3 Out[20]:

问题 This question already has answers here : Closed 10 years ago . Possible Duplicate: How do you calculate the average of a set of angles? I have two angles, a=20 degrees and b=350 degrees. The average of those two angles are 185 degrees. However, if we consider that the maximum angle is 360 degrees and allows for wrap around, one could see that 5 degrees is a closer average. I'm having troubles coming up with a good formula to handle that wrap around when calculating average. Anyone got any

问题 This question already has answers here : Closed 10 years ago . Possible Duplicate: How do you calculate the average of a set of angles? I have two angles, a=20 degrees and b=350 degrees. The average of those two angles are 185 degrees. However, if we consider that the maximum angle is 360 degrees and allows for wrap around, one could see that 5 degrees is a closer average. I'm having troubles coming up with a good formula to handle that wrap around when calculating average. Anyone got any

问题 I have a text file with n number of rows (separated by commas) and columns and I want to find average of each column, excluding empty field. A sample input looks like: 1,2,3 4,,6 ,7, The desired output is: 2.5, 4.5, 4.5 I tried with awk -F',' '{ for(i=1;i<=NF;i++) sum[i]=sum[i]+$i;if(max < NF)max=NF;};END { for(j=1;j<=max;j++) printf "%d\t",sum[j]/max;}' input But it treats consecutive delimiters as one and mixing columns. Any help is much appreciated. 回答1: You can use this one-liner: $ awk