a9r <- do.call(rbind, by(iris, iris[5], function(x) with(x, data.frame(Species = Species[1], mean.Sepal.Length = mean(Sepal.Length), mean.Sepal.Width = mean(Sepal.Width), mean.Sepal.ratio = mean(Sepal.Length/Sepal.Width))) ###do.call() 是告诉list一个函数,然后list里的所有元...
解决;R语言使用sqldf库是报错"Failed to connect to database: Error: Access denied for user '..'@'localhost' (using password: NO) Error in !dbPreExists : invalid argument type" 原因:在使用sqldf时,不需要加载RMySQL库 解决方案:在控制台执行释放RMySQL库加载 detach("package:RMySQL", unload=T);...
Solution R has a package calledsqldfthat allows developers to manipulate data inside a dataframe in the same way a SQL developer, queries a SQL table. In this tutorial I will show how to install the package and how to use it to query some values from the sample AdventureWorks2014 database....
0 sqldf select statements in R not working? 3 Sample Rows with SQLDF 0 Query returning 0 rows with sqldf package 0 package sqldf in R 0 SQL Select query not working using sqldf package in R 2 sqldf and POSIXct 0 sqldf() fails with "could not find function "sqldf" error 0 ...
clear_errors <- function(table, campo){ table <-as.data.frame(table) table[,campo] <-c(gsub("Ã'","Ñ",c(tabla_entrada[,campo]))) table[,campo]<-c(gsub("é","é",c(tabla_entrada[,campo]))) table[,campo]<-c(gsub("ó","ó",c(tabla_entrada[,campo]))) ...
week_num_f <- function(dates){ ##dates为报卡的日期向量,一个日期代表一个病例 df <- data.frame(date = dates) df$date <- as.character(ymd(df$date)) df$dnum <- 1##发病例数, 一行即代表1个病例 ##根据报卡数据,判断起止日期
function(x) { head(x[order(x$sample, decreasing = TRUE), ], 2) }) ## id date sample quality durability ## 1 T01 20160405 180 9 10 ## 2 T01 20160302 150 10 9 ## 3 T02 20160403 90 9 8 ## 4 T02 20160502 85 10 9
R SQLDF是一个R语言中的包,用于在R中执行SQL查询。它提供了一种简单且方便的方式来处理和操作数据框。通过使用SQL语句,可以从数据框中提取特定的值。 R SQLDF的主要功能包括: 1. ...
0 sqldf select statements in R not working? 1 Can't figure out why syntax error near "from" is appearing for sqldf in R 5 Error in R Using SQLDF: too many SQL variables 2 Error running a SQL query in R with sqldf 0 sqldf() fails with "could not find function "sqldf" error...
Note that PostgreSQL is the only free database that supports window functions (similar to ave function in R) which would allow a different formulation of the above. For more on using sqldf with PostgreSQL see FAQ #12 > library(RPostgreSQL) > library(sqldf) > tmp <- sqldf('select + "Spe...