Package data.table
URL https://r-datatable.com https://Rdatatable.gitlab.io/data.table
dplyr.pdf
5 ???????????? Different ways to select the same set of columns. # See <https://tidyselect.r-lib.org/articles/syntax.html> for details iris %>%.
14 Matrix expressions
matrix is a named entity containing an r ×c rectangular array of the resulting matrices you will find that they have row and column names that use only ...
?????????????????? Report Designer ???????????? ??????
17 ??.?. 2554 SELECT <Column> AS “New Heading”. ????????. SELECT hnCONCAT(pname
openxlsx: Read Write and Edit xlsx Files
14 ?.?. 2564 Get and set active sheet of the workbook. Usage. activeSheet(wb) ... colNames or col.names If TRUE column names of x are written.
Injecting SQLite database based application Manish Kishan Tanwar
14 ?.?. 2560 For column name extraction there is simple SQL query which extract column names for specific table. union SELECT 1sql
Solutions to the Exercises
29 ?.?. 2543 Solutions to Exercise 2-1: Using the SELECT Statement ... Display the business entity ID number the name columns
14 Matrix expressions
matrix is a named entity containing an r × c (0 < r ? matsize the resulting matrices
RSQLite: SQLite Interface for R
17 ?.?. 2565 dbGetQuery(db "SELECT * FROM CO2 WHERE conc < 100") ... If TRUE
RODBC: ODBC Database Access
16 ?.?. 2564 For DBMSs that translate table and column names case must be set ... Specify or retrieve a mapping of R types to DBMS datatypes.
dplyr: A Grammar of Data Manipulation - The Comprehensive R
name the unpacked columns This can use {outer} to refer to the name originally generated by names and {inner} to refer to the names of the data frame you are unpacking Value across() typically returns a tibble with one column for each column in cols and each function in fns
A short list of the most useful R commands - University of Sydney
apply(x2max) #finds the maximum for each column col max(x) #another way to find which column has the maximum value for each row
plotly
column numbers with “-” to drop bc dt[ (b c)] –extract columns by name a 6 a 2 6 5 EXTRACT dt[ (x = sum(a))] –create a data tablewith new columns based on the summarized values of rows Summary functions like mean() median() min() max() etc can be used to summarize rows dt[ (c = sum(b)) by = a]–summarize rows within
R Reference Card - The Comprehensive R Archive Network
get the column headers aligned correctly for spreadsheet input sink(file)output to file until sink() Most of the I/O functions have a file argument This can often be a charac-ter string naming a ?le or a connection file="" means the standard input or output Connections can include ?les pipes zipped ?les and R variables
Data Wrangling - A foundation for wrangling in R - RStudio
Select columns whose names are in a group of names select(iris starts_with("Sepal")) Select columns whose name starts with a character string select(iris Sepal Length:Petal Width) Select all columns between Sepal Length and Petal Width (inclusive) select(iris -Species) Select all columns except Species
Searches related to get column name r filetype:pdf
median() #get the median of the values in x by median(x) sd() #get the standard deviation of the values in x var() #get the variance of the values in x IQR() #get the IQR of the values in x summary() #get the summary statistics of a single variable or of all variables in a data frame
How to rename multiple columns in R?
- rename () – rename the old column name with a new name. Rename multiple column at once using rename () function. rename a column name on a specific condition using rename_if () function in R. We will be using Orange data to depict the rename of column variable.
How do I combine columns in R?
- How do I combine variables in R? If datasets are in different locations, first you need to import in R as we explained previously. You can merge columns, by adding new variables; or you can merge rows, by adding observations. To add columns use the function merge() which requires that datasets you will merge to have a common variable. .
How to merge two columns in R?
- paste (objects, sep=" ") Here, “objects” refers to any R objects you will be merging (in our case it will be two columns). The “sep= ” “” allows you to input a character that will separate the values in the new column. It can be empty, include spaces, symbols, letters, numbers, or any combinations of them. Part 2.
How to add column to Dataframe in R?
- You can use the mutate() function from the dplyr package to add one or more columns to a data frame in R. This function uses the following basic syntax: Method 1: Add Column at End of Data Frame. df %>% mutate (new_col=c(1, 3, 3, 5, 4)) Method 2: Add Column Before Specific Column. df %>% mutate (new_col=c(1, 3, 3, 5, 4), .before=col_name)
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