大约有 40,900 项符合查询结果(耗时:0.0285秒) [XML]

https://stackoverflow.com/ques... 

Mean per group in a data.frame [duplicate]

....table(text= 'Name Month Rate1 Rate2 Aira 1 12 23 Aira 2 18 73 Aira 3 19 45 Ben 1 53 19 Ben 2 22 87 Ben 3 19 45 Cat 1 22 87 Cat 2 67 43 Cat ...
https://stackoverflow.com/ques... 

How can I delete one element from an array by value

... I think I've figured it out: a = [3, 2, 4, 6, 3, 8] a.delete(3) #=> 3 a #=> [2, 4, 6, 8] share | improve this answer | follow ...
https://stackoverflow.com/ques... 

How can I sort a dictionary by key?

What would be a nice way to go from {2:3, 1:89, 4:5, 3:0} to {1:89, 2:3, 3:0, 4:5} ? I checked some posts but they all use the "sorted" operator that returns tuples. ...
https://stackoverflow.com/ques... 

For each row return the column name of the largest value

...amples using sample reproducible): DF <- data.frame(V1=c(2,8,1),V2=c(7,3,5),V3=c(9,6,4)) colnames(DF)[apply(DF,1,which.max)] [1] "V3" "V1" "V2" A faster solution than using apply might be max.col: colnames(DF)[max.col(DF,ties.method="first")] #[1] "V3" "V1" "V2" ...where ties.method can be...
https://stackoverflow.com/ques... 

Applying a function to every row of a table using dplyr?

... | edited Aug 6 '19 at 3:20 answered Jul 14 '14 at 0:20 ...
https://stackoverflow.com/ques... 

How do you match only valid roman numerals with a regular expression?

... 330 You can use the following regex for this: ^M{0,4}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0...
https://stackoverflow.com/ques... 

Does assignment with a comma work?

Why does aaa = 1,2,3 work and set the value of aaa to 1 ? 4 Answers 4 ...
https://stackoverflow.com/ques... 

“ValueError: zero length field name in format” error in Python 3.0,3.1,3.2

I'm trying learn Python (3 to be more specific) and I'm getting this error: 3 Answers ...
https://stackoverflow.com/ques... 

Version of SQLite used in Android?

...database.sqlite package-level javadoc Using the emulators: adb shell sqlite3 --version UPDATE: Since SDK 29 (emulator revision 8), the adb shell command gives: /system/bin/sh: sqlite3: inaccessible or not found Any ideas why? Issue tracker here. SQLite 3.28.0 (window functions!): 30-11.0-R (Re...
https://stackoverflow.com/ques... 

Reshape three column data frame to matrix (“long” to “wide” format) [duplicate]

...similar questions scattered around this site. tmp <- data.frame(x=gl(2,3, labels=letters[24:25]), y=gl(3,1,6, labels=letters[1:3]), z=c(1,2,3,3,3,2)) Using the tidyverse: The new cool new way to do this is with pivot_wider from tidyr 1.0.0. It returns a d...