大约有 47,000 项符合查询结果（耗时：0.0335秒） [XML]
Dynamically select data frame columns using $ and a character value
...is a reproducible example below:
# set seed for reproducibility
set.seed(123)
df <- data.frame( col1 = sample(5,10,repl=T) , col2 = sample(5,10,repl=T) , col3 = sample(5,10,repl=T) )
# We want to sort by 'col3' then by 'col1'
sort_list <- c("col3","col1")
# Use 'do.call' to call order. S...
Python Pandas: Get index of rows which column matches certain value
...ool (PS: about how to use it please check link )
df.query('BoolCol')
Out[123]:
BoolCol
10 True
40 True
50 True
After we filter the original df by the Boolean column we can pick the index .
df=df.query('BoolCol')
df.index
Out[125]: Int64Index([10, 40, 50], dtype='int64')
Als...
Detecting syllables in a word
...
123
Read about the TeX approach to this problem for the purposes of hyphenation. Especially see Fr...
How to assign name for a screen? [closed]
...ie Alpert
120k3535 gold badges206206 silver badges231231 bronze badges
answered Jul 8 '10 at 9:29
miedwarmiedwar
7,10011 gold badg...
How to convert an NSString into an NSNumber
...
For strings starting with integers, e.g., @"123", @"456 ft", @"7.89", etc., use -[NSString integerValue].
So, @([@"12.8 lbs" integerValue]) is like doing [NSNumber numberWithInteger:12].
share...
What's the difference between VARCHAR and CHAR?
...
123
CHAR Vs VARCHAR
CHAR is used for Fixed Length Size Variable
VARCHAR is used for Variable Leng...
Why are hexadecimal numbers prefixed with 0x?
...h is nicely divisible by 3 = log2(8).
The BCPL language used the syntax 8 1234 for octal numbers. When Ken Thompson created B from BCPL, he used the 0 prefix instead. This is great because
an integer constant now always consists of a single token,
the parser can still tell right away it's got a c...
How to get everything after a certain character?
...e, then substr grabs everything from that index plus 1, onwards.
$data = "123_String";
$whatIWant = substr($data, strpos($data, "_") + 1);
echo $whatIWant;
If you also want to check if the underscore character (_) exists in your string before trying to get it, you can use the following:...
Store password in TortoiseHg
...the name of your GC project. So something like:
default = https://fred:xyz123@fredproj.googlecode.com/hg/
share
|
improve this answer
|
follow
|
...
Reasons for using the set.seed function
... "42" is a reference to a famous book; other people use their birthday or "123" or just "1".
– Dirk Eddelbuettel
Nov 30 '12 at 1:30
7
...