R language Common functions & R language Other

Operational database (RODBC)

Odbcconnect (DSN, uid= "", pwd= "") Establish a connection to the ODBC database

SqlFetch (channel, sqltable) reads a table from an ODBC database into a data frame

SQLQuery (channel, query) submits a query to ODBC and returns the result

Sqlsave (channel, Dataframe, Tablename=table, Append=false, rowname=true) write or update a data frame to a table in an ODBC database

Sqlupdate (channel, Dataframe, Tablename=table, Append=false, Rowname=true, index= "")

Sqldrop (channel, table) delete a table (physical delete)

Sqlclear (channel, table) delete data from a table

Close (channel) Closed connection

Length (object)

Statement Variable[condition] <-expression will only perform an assignment if the value of condition is true.

Eg:leadership$agecat[leadership$age >] <-"Elder"

Rename rename (Dataframe, C (oldname= "NewName", oldname= "NewName", ...)) (Reshape bag)

Sort order (object)

Rank (object) returns the sorted ordinal number

Manipulating data frames using SQL statements (SQLDF): Sqldf (SQL): Use only select statements

NA (not available): Unavailable

NaN (not a number): Non-numeric

Determine if NA:is.na (object)

Remove na value: Na.omit (Object)

apply () function: You can "apply" an arbitrary function to any dimension of a matrix, an array, a data frame
Apply (x, MARGIN, fun, ...)

where x is the data object, MARGIN is the subscript of the dimension, Fun is the function you specify, and ... Includes any arguments that you want to pass to the fun. In a matrix or data frame, margin=1 represents a row, margin=2 represents a column

Stitching strings: Paste0 (str1, str2, ...)

Type conversions:

　

Logical operators:

　　

Arithmetic operators:

　　

Control Flow:

for (ver in SEQ) statement

while (condition) statement

if (condition) statement Else statement

IfElse (Conditon, STATEMETN1, Statement2)

R language Common functions & R language Other