How do I disable buffering in fread()?
来源： https://stackoverflow.com/questions/8699397/how-do-i-disable-buffering-in-fread
fread
How do I disable buffering in fread()?
来源： https://stackoverflow.com/questions/8699397/how-do-i-disable-buffering-in-fread
How do I disable buffering in fread()?
来源： https://stackoverflow.com/questions/8699397/how-do-i-disable-buffering-in-fread
Read a line from file in C and extract the number of input
来源： https://stackoverflow.com/questions/63457609/read-a-line-from-file-in-c-and-extract-the-number-of-input
Read a line from file in C and extract the number of input
来源： https://stackoverflow.com/questions/63457609/read-a-line-from-file-in-c-and-extract-the-number-of-input
Read a line from file in C and extract the number of input
来源： https://stackoverflow.com/questions/63457609/read-a-line-from-file-in-c-and-extract-the-number-of-input
What is the fastest way and fastest format for loading large data sets into R [duplicate]
问题 This question already has answers here : Quickly reading very large tables as dataframes (11 answers) Closed 4 years ago . I have a large dataset (about 13GB uncompressed) and I need to load it repeatedly. The first load (and save to a different format) can be very slow but every load after this should be as fast as possible. What is the fastest way and fastest format from which to load a data set? My suspicion is that the optimal choice is something like saveRDS(obj, file = 'bigdata.Rda',
Fast reading and combining several files using data.table (with fread)
问题 I have several different txt files with the same structure. Now I want to read them into R using fread, and then union them into a bigger dataset. ## First put all file names into a list library(data.table) all.files <- list.files(path = "C:/Users",pattern = ".txt") ## Read data using fread readdata <- function(fn){ dt_temp <- fread(fn, sep=",") keycols <- c("ID", "date") setkeyv(dt_temp,keycols) # Notice there's a "v" after setkey with multiple keys return(dt_temp) } # then using mylist <-
fread和fseek的用法
原味：http://baike.baidu.com/view/656696.htm http://baike.baidu.com/view/656689.htm fread 功 能: 从一个流中读数据 函数原型: size_t fread( void * buffer , size_t size , size_t count , FILE * stream ); 参 数： 1.用于接收数据的地址（指针）（ buffer ） 2.单个元素的大小（size） ：单位是字节而不是位，例如读取一个整型数就是2个字节 3.元素个数（ count ） 4.提供数据的文件指针（stream） 返回值：成功读取的元素个数 程序例 #include <stdio.h> int main(void) { FILE *stream; char msg[] = "this is a test"; char buf[20]; if ((stream = fopen("DUMMY.FIL","w+")) == NULL ) { fprintf(stderr,"Cannot open output file.\n"); return 1; } fwrite(msg,strlen(msg)+1,1,stream); fseek(stream,0,SEEK_SET);
【FBI WARNING】读入优化
感觉这个优化挺重要的，毕竟在2017NOIP提高的那个奶酪问题 写出代码来 就只是读入感觉就超时 过了样例又如何？ 最后还不是TLE。 对于输入数据非常大的一些可（变）爱（态）题目，scanf就会大大拖慢程序的运行速度，cin就更不用说了，所以我们要用一种高大上的东西——读入优化。 读入优化的原理其实就是一个一个字符的读入，再组成数字 ---Peper（我百度找的） 插入一套比较简单的读入优化 当然 对于我来说还是比较简（困）单（难）的。 1 int read() 2 { 3 int x=0,f=1; 4 char ch; 5 while(ch<'0'||ch>'9') {if(ch=='-')f=-1;ch=getchar();} 6 while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} 7 return f*x; 8 } 这就是 最基本 的读入优化，通过getchar函数依次读入字符，用x记录答案，用f判断正负。 ps：在主程序中调用时int n=read();即可 ===========================前方高能预警=============================== 在插一套某大佬的版子 template<class T>void read(T &x) { x=0;int f=0;char ch