大约有 4,768 项符合查询结果（耗时：0.0248秒） [XML]
Resetting generator object in Python
I have a generator object returned by multiple yield. Preparation to call this generator is rather time-consuming operation. That is why I want to reuse the generator several times.
...
What is the use of “ref” for reference-type variables in C#?
I understand that if I pass a value-type ( int , struct , etc.) as a parameter (without the ref keyword), a copy of that variable is passed to the method, but if I use the ref keyword a reference to that variable is passed, not a new one.
...
How to find the last day of the month from date?
How can I get the last day of the month in PHP?
28 Answers
28
...
How to fix the aspect ratio in ggplot?
I'm trying to resize a plot to fit into my document, but I'm having difficulties getting the plotted diagram do be a square.
...
How to assign colors to categorical variables in ggplot2 that have stable mapping?
...For simple situations like the exact example in the OP, I agree that Thierry's answer is the best. However, I think it's useful to point out another approach that becomes easier when you're trying to maintain consistent color schemes across multiple data frames that are not all obtained by subsettin...
Split column at delimiter in data frame [duplicate]
..., but then just some more magic to make it into a data.frame.
I added a "x|y" line to avoid ambiguities:
df <- data.frame(ID=11:13, FOO=c('a|b','b|c','x|y'))
foo <- data.frame(do.call('rbind', strsplit(as.character(df$FOO),'|',fixed=TRUE)))
Or, if you want to replace the columns in the exis...
Annotating text on individual facet in ggplot2
...
Typically you'd do something like this:
ann_text <- data.frame(mpg = 15,wt = 5,lab = "Text",
cyl = factor(8,levels = c("4","6","8")))
p + geom_text(data = ann_text,label = "Text")
It should work wi...
Javascript calculate the day of the year (1 - 366)
How do I use javascript to calculate the day of the year, from 1 - 366? For example:
22 Answers
...
How to convert a boolean array to an int array
I use Scilab, and want to convert an array of booleans into an array of integers:
6 Answers
...
How to drop columns by name in a data frame
...
You should use either indexing or the subset function. For example :
R> df <- data.frame(x=1:5, y=2:6, z=3:7, u=4:8)
R> df
x y z u
1 1 2 3 4
2 2 3 4 5
3 3 4 5 6
4 4 5 6 7
5 5 6 7 8
Then you can use the which fun...