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How to append rows to an R data frame
...<- function(n){
df <- data.frame(x = numeric(n), y = character(n), stringsAsFactors = FALSE)
for(i in 1:n){
df$x[i] <- i
df$y[i] <- toString(i)
}
df
}
Here's a similar approach, but one where the data.frame is created as the last step.
# Use preallocated vectors
f4 <...
Throw keyword in function's signature
...lowing code?
#include <iostream>
void throw_exception() throw(const char *)
{
throw 10;
}
void my_unexpected(){
std::cout << "well - this was unexpected" << std::endl;
}
int main(int argc, char **argv){
std::set_unexpected(my_unexpected);
try{
throw_excepti...
Changing variable names in Vim
...nvar()
expand("<cword>") gets the word under the cursor. The search string uses % for file-scope, and the \(\W\) patterns look for non-word characters at the boundary of the word to replace, and save them in variables \1 and \2 so as to be re-inserted in the replacement pattern.
...
How to display pandas DataFrame of floats using a format string for columns?
... think you'll have to pre-modify the dataframe (converting those floats to strings):
import pandas as pd
df = pd.DataFrame([123.4567, 234.5678, 345.6789, 456.7890],
index=['foo','bar','baz','quux'],
columns=['cost'])
df['foo'] = df['cost']
df['cost'] = df['cost']...
OceanBase使用libeasy原理源码分析：服务器端 - 数据库(内核) - 清泛网 - ...
... 得到easy_request_t中成员request_list_node的指针
(type *)( (char *)__mptr - offsetof(type,member) );}) // 指针减去 request_list_node成员在easy_request_t中的偏移就得到了easy_request_t的首地址
其中offsetof(type,member)是得到member这个这个...
What are free monads?
...gives you a way to "get out" of it.
More generally, if X is a Y with some extra stuff P, then a "free X" is a a way of getting from a Y to an X without gaining anything extra.
Examples: a monoid (X) is a set (Y) with extra structure (P) that basically says it has an operation (you can think of add...
How can I get query string values in JavaScript?
Is there a plugin-less way of retrieving query string values via jQuery (or without)?
73 Answers
...
Convert a string to an enum in C#
What's the best way to convert a string to an enumeration value in C#?
25 Answers
25
...
Get value of c# dynamic property via string
I'd like to access the value of a dynamic c# property with a string:
11 Answers
11
...
ActiveRecord: List columns in table from console
...ou can just type the model name:
> User
gives:
User(id: integer, name: string, email: string, etc...)
In rails four, you need to establish a connection first:
irb(main):001:0> User
=> User (call 'User.connection' to establish a connection)
irb(main):002:0> User.connection; nil #call ...