In Example 3, we will access and extract certain columns with the subset function. Within the subset function, we need to specify the name of our data matrix (i.e. data) and the columns we want to select (i.e. x1 and x3): subset(data,select=c("x1","x3"))# Subset with select ...
In Example 1, I’ll explain how to select certain columns based on a logical condition using thegrepl function. Have a look at the following R code: data_new1<-data[, grepl("x", colnames(data))]# Extract by logicaldata_new1# Print updated data# x1 x2 x3# 1 1 x 9# 2 2 x ...
cnnstr <-"Data Source=localhost; Provider=MSOLAP; initial catalog=Analysis Services Tutorial"ocs <- OlapConnection(cnnstr) mdx <-"SELECT {[Measures].[Internet Sales Count], [Measures].[InternetSales-Sales Amount]} ON COLUMNS, {[Product].[Product Line].[Product Line].MEMBERS} ...
connStr <-"Server=.;Database=TestDB;Trusted_Connection=Yes"data <- RxSqlServerData(connectionString = connStr, sqlQuery ="SELECT COLUMN_NAME FROM TestDB.INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = N'testdata' AND DATA_TYPE <> 'image';") columns <- rxImport(data) columnList <- do.ca...
select(): Extract one or multiple columns as a data table. It can be also used to remove columns from the data frame. select_if(): Select columns based on a particular condition. One can use this function to, for example, select columns if they are numeric. ...
cnnstr <- "Data Source=localhost; Provider=MSOLAP;" olapCnn <- OlapConnection(cnnstr) qry <- Query() cube(qry) <- "[Analysis Services Tutorial]" columns(qry) <- c("[Measures].[Internet Sales Count]", "[Measures].[Internet Sales-Sales Amount]") rows(qry) <- c("[Product].[Produc...
解决R语言中出现的“undefined columns selected in data”参数错误 在R语言中,有时候我们会碰到一个错误提示:“undefined columns selected in data”,这是因为我们在使用某些函数时,传入的参数在数据集中并不存在。这个错误可能会让我们感到困惑,不知道如何解决。在本文中,我们将介绍这个错误的原因以及如何解决它。
We can view the output tibble/dataframe,works_from_dois, interactively in RStudio or inspect it with base functions likestrorhead. We also provide the experimentalshow_worksfunction to simplify the result (e.g., remove some columns, keep first/last author) for easy viewing. ...
rename_columns These operations are easy to demonstrate. We set up some simple data. d<-data.frame(x=c(1,1,2),y=c(5,4,3),z=c(6,7,8) )knitr::kable(d) xyz 156 147 238 For example:drop_columnsworks as follows.drop_columnscreates a newdata.framewithout certain columns. ...
# 假设我们想导出df的A和B列 columns_to_export <- df[, c("A", "B")] # 使用cat()函数将列数据导出为文本文件 con <- file("df_columns.txt", "w") for (i in 1:nrow(columns_to_export)) { cat(columns_to_export[i, "A"], ",", columns_to_export[i, "B"], "\n", file =...