grepl

The regular expression of R language is mainly used to deal with textual data, such as searching, replacing and so on.The first is some of the functions that will be used when working with text:String split: Strsplit ()String connection: Paste (), Paste0 ()Calculate string Length: nchar (), Length ()String intercept: substr (), substring ()See if there is a character: grep (P,X) GREPL (P,X) Give me a chestnut: s " 123abc\\456 " , " abc123edf " Span

, author and other relations6 #Article release time7Sample (R_blog[grep ("Posted:", R_blog)],10)8 #article title9Sample (R_blog[grep ("Posted:", R_blog) -2],10)Ten #article author OneSample (R_blog[grep ("Posted:", R_blog) +3],5) A - #3, according to the above information, according to the article split long text (4.5M) - the #4, the library as a condition to see what the recent popular libraries -Library_list"^library\\ (", R_blog)],"\\(|\\)|\\,") -Library_list]) -Library_list"\\p{p}","", lib

the data preprocessing phase you need to skillfully manipulate the string object. Of course, if you are good at other processing software, such as Python, you can make it responsible for the dirty work of the previous period.String intercept: substr () can take a subset of a given string object, whose parameters are the starting and ending positions of the subset.String substitution: gsub () is responsible for searching the specific expression of the string and substituting the new content. The

-A3-A4-A5-A6"Substr String truncation Function substr(x = "hello", start = 1, stop = 2)[1] "he"Strsplit String delimiter to generate a list strsplit("abc", split = "")[[1]][1] "a" "b" "c" If you want to use this function for a vector, pay attention to it. # Divide each element of a vector and obtain the unlist (lapply (X = c ("abc", "bcd", "dfafadf") of the first element after the split "), FUN = function (x) {return (strsplit (x, split = "") [[1] [1])}) [1] "a" "B" "d"Gsub and sub String replac

://d396qusza40orc.cloudfront.net/getdata%2Fdata%2FGDP.csv",DestFile = "Q2.csv",method = "Curl")# Load LibraryLibrary (PLYR)Library (DPLYR)# load CSV fileQ2 # Reshape DataQ2 Rownames (Q2) Q2 Names (Q2) Replacement = "",x = names (Q2))Names (Q2) # Remove the comma in column UsdollarsQ2$usdollars Replacement = "",x = q2$usdollars)# convert Usdollars to numericQ2$usdollars # Calculate the average of usdollarsMean (x = q2$usdollars, na.rm = TRUE)# quesetion 3# Change the column name to match the ques

a vector, you need to be aware of it.# 分割向量的每一个元素，并取分割后的第一个元素unlist(lapply(X = c("abc""bcd""dfafadf"function(x) {return"")[[1]][1])}))[1"a""b""d"Gsub and SubString substitutiongsub Replace all matches toThe sub replaces the first one that matches the# Replace B with BGsub (pattern ="B", replacement ="B", x ="Baby")[1]"BaBy"Gsub (pattern ="B", replacement ="B", x = C ("ABCB","Boy.","Baby"))[1]"ABCB" "Boy." "BaBy"# Replace only the first BSub (pattern ="B", replacement ="B", x ="Baby")[1]"Baby"S

#实现了单一模式匹配后, in order to achieve the overall two-group data fuzzy matching further optimization. RM (list = ls ())Library (Tidyr)Library (DPLYR)Library (Lubridate)Library (Rjava)Library (Xlsxjars)Library (XLSX)Library (data.table)Library (READR)Library (READXL)SETWD (' g:\\r\\data\\0423 ')Dir ()Data1 Data2 DATA1$BZ For (J in 1:nrow (Data1)) {For (I-in 1:nrow (data2)) {if (GREPL (pattern = data2$gysh[i],data1$gysh[j]) = = TRUE) {DATA1$BZ[J] Print (i)}

= ' echo "$sysmem" |grepl|awk ' begin{sum1=0;} {sum1=sum1+$2;} END{SUM1=SUM1*16*1024;PRINTNBSP;SUM1;} ' ' mediumseg= ' echo "$sysmem" |grepm|awk ' begin{sum1=0;} {sum1=sum1+$2;} END{SUM1=SUM1*64;PRINTNBSP;SUM1;} ' ' smallseg= ' echo "$sysmem" |greps|awk ' begin{sum1=0;} {sum1=sum1+$2;} END{SUM1=SUM1*4;PRINTNBSP;SUM1;} ' ' Sysmem=$ (expr $supremeseg + $largeseg + $mediumseg + $smallseg) sysmem=$ ( expr $sysmem /1024) echo "System memory (physical memor

braces {} are used together with "|"Note:Escape Character \ is required to escape all reserved charactersFor example:Meanings of Common special escape characters \ N: linefeed\ T: tab\ W: Any letter (including underscores) or number is [a-zA-Z0-9 _]\ W: \ w antsense is [^ a-zA-Z0-9 _]\ D: Any number [0-9]\ D: \ d's antsense is [^ 0-9]\ S: any space, such as space, tab, newline, etc.\ S: \ s. Any non-spaceCommon Regular Expression Functions Grepl: ret

1.　　re.sub? Signature:re.sub (Pattern, REPL, String, Count=0, flags=0) Docstring:return the string obtained by replacing the L Eftmostnon in string by Thereplacement repl. or a callable; if in it is processed. is a callable, it ' s passed the match object and must returna replacement string to be used.Parameter description: Pattern string, can be numerically named can also name name (\gRepl replaced string can also be a function string source str

uppercase characters)–[A-ZA-Z]: any one English letter–[a-z]+: One or more lowercase English letters| OrParentheses () with curly braces {} with "|" UseSpecial Note: reserved characters require the escape character \ to escape the representationFor example:common meaning of special escape characters? \ n: Line break? \t:tab? \w: Any letter (including underscores) or numbers [a-za-z0-9_]? \w:\w's antisense meaning is [^a-za-z0-9_]? \d: Any number that is [0-9]? \d:\d's antisense meaning is [^0-9