difference

问题 My DataFrame is in the Form: TimeWeek TimeSat TimeHoli 0 6:40:00 8:00:00 8:00:00 1 6:45:00 8:05:00 8:05:00 2 6:50:00 8:09:00 8:10:00 3 6:55:00 8:11:00 8:14:00 4 6:58:00 8:13:00 8:17:00 5 7:40:00 8:15:00 8:21:00 I need to find the time difference between each row in TimeWeek , TimeSat and TimeHoli, the output must be TimeWeekDiff TimeSatDiff TimeHoliDiff 00:05:00 00:05:00 00:05:00 00:05:00 00:04:00 00:05:00 00:05:00 00:02:00 00:04:00 00:03:00 00:02:00 00:03:00 00:02:00 00:02:00 00:04:00 I

问题 Is there any difference between (\w+)? and (\w*) in regex? It seems the same, doesn't it? 回答1: (\w+)? and (\w*) both match the same (0..+inf word characters) However, there is a slight difference: In the first case, if this part of the regex matches "" , the capturing group is absent. In the second case, it is empty. In some languages, the former manifests as a null while the latter should always be "" . In Javascript, for example, /(\w*)/.exec("") // ["", ""] /(\w+)?/.exec("") // ["",

问题 Is there any difference between (\w+)? and (\w*) in regex? It seems the same, doesn't it? 回答1: (\w+)? and (\w*) both match the same (0..+inf word characters) However, there is a slight difference: In the first case, if this part of the regex matches "" , the capturing group is absent. In the second case, it is empty. In some languages, the former manifests as a null while the latter should always be "" . In Javascript, for example, /(\w*)/.exec("") // ["", ""] /(\w+)?/.exec("") // ["",

问题 i have a question about enums that the codes are below: namespace space { public enum MyEnums { Enum1,Enum2,... } } namespace space { public class MyClass { public enum MyEnums { Enum1,Enum2,... } } } whats difference and how to use them? 回答1: Well syntactically the only difference is that you'd preface the enum type with the containing class: MyClass.MyEnums.Enum1 versus just MyEnums.Enum1 (in both cases the namespace is assumed to be covered with a using directive) However, containing it

问题 I try to mutate new column to data.frame. When V column order changes from decreasing to increasing order, I use diff function inside of mutate to categorize them in new column H . V <- c(seq(30,-10,-10),seq(-10,30,10)) gr = rep(seq(1,3),each=10) df <- data.frame(V,gr) library(dplyr) diff_df <- df%>% group_by(gr)%>% mutate(H=ifelse(diff(V)<0,"back","forward")) However getting error Error: incompatible size (9), expecting 10 (the group size) or 1 But when I do diff(df$V) [1] -10 -10 -10 -10 0

问题 I'm trying to make something like this: if (datetime - system date > 15 minutes) (false) if (datetime - system date <= 15 minutes) (true) But I'm totally lost. I don't know how to make this operation in PHP. I'd like to see how I can pick that DateTime from my database and check if it's between the last 15 minutes of my server's time. The type of database is MySQL. Finally, I managed to do it thanks to Sammitch and the other ones, here i leave the snippet: $now = time(); $target = strtotime(

问题 This question already has answers here : rank and order in R (7 answers) Closed last year . What is the difference between sort(), rank(), and order() in R . Can you explain with examples? 回答1: sort() sorts the vector in an ascending order. rank() gives the respective rank of the numbers present in the vector, the smallest number receiving the rank 1. order() returns the indices of the vector in a sorted order. for example: if we apply these functions are applied to the vector - c (3, 1, 2, 5

问题 I have 2 CSV files of same dimensions. In the below example used the dimensions is 3*3 (3 comma separated values and 3 rows). It could be files of dimensions 100*10000 File1.csv: Name, ID, Profession Tom, 1, Teacher Dick, 2, Actor File2.csv: Name, ID, Profession Dick, 2, Actor Tom, 1, Police I want to compare the files element wise (e.g: Teacher == Police) It would be great if I could compare the lists using primary key (ID) in case the list is not in order. I would like to have output

问题 When scraping multiple websites in a loop, I notice there is a rather large difference in speed between, sleep(10) response = requests.get(url) and, response = requests.get(url, timeout=10) That is, timeout is much faster. Moreover, for both set-ups I expected a scraping duration of at least 10 seconds per page before requesting the next page, but this is not the case. Why is there such a difference in speed? Why is the scraping duration per page less than 10 seconds? I now use

问题 I'm learning TensorFlow and Keras. I'd like to try https://www.amazon.com/Deep-Learning-Python-Francois-Chollet/dp/1617294438/, and it seems to be written in Keras. Would it be fairly straightforward to convert code to tf.keras ? I'm not more interested in the portability of the code, rather than the true difference between the two. 回答1: At this point tensorflow has pretty much entirely adopted the keras API and for a good reason - it's simple, easy to use and easy to learn, whereas "pure"