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5 ???????????? Different ways to select the same set of columns. # See <https://tidyselect.r-lib.org/articles/syntax.html> for details iris %>%.
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 ...
17 ??.?. 2554 SELECT <Column> AS “New Heading”. ????????. SELECT hnCONCAT(pname
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.
14 ?.?. 2560 For column name extraction there is simple SQL query which extract column names for specific table. union SELECT 1sql
29 ?.?. 2543 Solutions to Exercise 2-1: Using the SELECT Statement ... Display the business entity ID number the name columns
matrix is a named entity containing an r × c (0 < r ? matsize the resulting matrices
17 ?.?. 2565 dbGetQuery(db "SELECT * FROM CO2 WHERE conc < 100") ... If TRUE
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.
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
apply(x2max) #finds the maximum for each column col max(x) #another way to find which column has the maximum value for each row
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
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
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
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