I have column having values like "xxxxTxxx" or "xxTxx", always separated by 'T', I i want to extract the first part of the string, that is prior to 'T', AND, saved it in another column.
a <- c("abcT123","Dsds1Tdf4")
i get to get a table with 3 columns as below:
a b c
abcT123 abc 123
Dsds1Tdf4 Dsds Tdf4
Can you please help?
Try
cbind(a,do.call(rbind,strsplit(a,"T")))
Result:
a
[1,] "abcT123" "abc" "123"
[2,] "Dsds1Tdf4" "Dsds1" "df4"
Look at ?strsplit.
Related
I am trying to find 3 or more consecutive "a" within the last 10 letters of my data frame string. My data frame looks like this:
V1
aaashkjnlkdjfoin
jbfkjdnsnkjaaaas
djshbdkjaaabdfkj
jbdfkjaaajbfjna
ndjksnsjksdnakns
aaaandfjhsnsjna
I have written this code, however it just gets out the number of consecutive "a" within the whole string. However, I am wanting to do it so it only looks at the last 10 digits and then prints the string where the consecutive "a" are found. The code I have wrote is:
out: [1] 3
I am wanting my output to look like this:
jbfkjdnsnkjaaaas
djshbdkjaaabdfkj
jbdfkjaaajbfjna
Can anyone help
Using regex, you could do:
grep("(?=.{10}$).*?a{3,}", string, perl = TRUE, value = TRUE)
[1] "jbfkjdnsnkjaaaas" "djshbdkjaaabdfkj" "jbdfkjaaajbfjna"
string <- c("aaashkjnlkdjfoin", "jbfkjdnsnkjaaaas", "djshbdkjaaabdfkj",
"jbdfkjaaajbfjna", "ndjksnsjksdnakns", "aaaandfjhsnsjna")
If you have a dataframe and need tosubset it:
subset(df, grepl("(?=.{10}$).*?a{3}",V1, perl = TRUE))
V1
2 jbfkjdnsnkjaaaas
3 djshbdkjaaabdfkj
4 jbdfkjaaajbfjna
Hello I would like to select rows in form of list from a dataframe. Here is my dataframe:
df2 <- data.frame("user_id" = 1:2, "username" = c(215,154), "password" = c("John4","Dora4"))
now with this dataframe I can only select 1 column to view rows as a list, which I did with this code
df2[["user_id"]]
output is
[1] 1 2
but now when I try this with more columns I am told its out of bounds, what is the problem here
df2[["user_id", "username"]]
How can I resolve and get the results of rows as a list
If I understood your question correctly, you need to familiarize yourself with subsetting in R. These are ways to select multiple columns in R:
df2[,c('user_id', 'username')]
or
df2[,1:2]
If you want to return all columns as a list, you can use something like this:
lapply(1:ncol(df2), function(x) df2[,x])
The format is df2['rows','columns'], so you should use:
df2[,c("user_id", "username")]
To get them 'in form of list', do:
as.list(df2[,c("user_id", "username")])
The double bracket [[ notion is used to select a single unnamed element (in this case a single unnamed column since data frames are essentially lists of column data).
See this answer for more on double vs single bracket notion: https://stackoverflow.com/a/1169495/8444966
This should give you a row of list (There's got to be an answer somewhere here).
row_list<- as.list(as.data.frame(t(df2[c("user_id", "username")])))
#$V1
#[1] 1 215
#$V2
#[1] 2 154
If you want to keep names of the rows.
df2_subset <- df2[c("user_id", "username")]
setNames(split(df2_subset, seq(nrow(df2_subset))), rownames(df2_subset))
#$`1`
# user_id username
#1 1 215
#$`2`
# user_id username
#2 2 154
Working with a data frame in R studio. One column, PODMap, has sentences such as "At my property there is a house at 38.1234, 123.1234 and also I have a car". I want to create new columns, one for the latitude and one for the longitude.
Fvalue is the data frame. So far I have
matches <- regmatches(fvalue[,"PODMap"], regexpr("..\\.....", fvalue[,"PODMap"], perl = TRUE))
Since the only periods in the text are in longitude and latitude, this returns the first lat or long listed in each string (still working on finding a regex to grab the longitude from after the latitude but that's a different question). The problem is, for instance, if my vector is c("test 38.1111", "x", "test 38.2222") then it returns (38.1111. 38.2222) which has the right values, but the vector won't be the right length for my data frame and won't match. I need it to return a blank or a 0 or NA for each string that doesn't have the value matching the regular expression, so that it can be put into the data frame as a column. If I'm going about this entirely wrong let me know about that too.
You can use regexecwhich returns a list of the same length so you don't loose the non-match spaces
PODMap<-c("At my property there is a house at 38.1234, 123.1234 and also I have a",
"Test TEst TEST Tes T 12.1234, 123.4567 test Tes",
"NO LONG HEre Here No Lat either",
"At my property there is a house at 12.1234, 423.1234 and also I have ")
Index<-c(1:4)
fvalue<-data.frame(Index,PODMap)
matches <- regmatches(fvalue[,"PODMap"], regexec("..\\.....", fvalue[,"PODMap"], perl
= TRUE))
> matches
[[1]]
[1] "38.1234"
[[2]]
[1] "12.1234"
[[3]]
character(0)
[[4]]
[1] "12.1234"
Using the package stringr, we can get both the long and lat.
library(stringr)
matches<-str_match_all(fvalue[,"PODMap"], ".\\d\\d\\.\\d\\d\\d\\d")
> matches
[[1]]
[,1]
[1,] " 38.1234"
[2,] "123.1234"
[[2]]
[,1]
[1,] " 12.1234"
[2,] "123.4567"
[[3]]
[,1]
[[4]]
[,1]
[1,] " 12.1234"
[2,] "423.1234"
The \\d checks for any digit 1:9, so that will keep out any words, and we use str_match_all to get all the matches from the string, as regmatches will only take the first match. str_match_all will set a value to NULL instead of character(0) though, which should not be a problem.
Check out this regex demo
I am using readLines() to extract an html code from a site. In almost every line of the code there is pattern of the form <td>VALUE1<td>VALUE2<td>. I would like to take the values in between the <td>. I tried some compilations such as:
output <- gsub(pattern='(.*<td>)(.*)(<td>.*)(.*)(.*<td>)',replacement='\\2',x='<td>VALUE1<td>VALUE2<td>')
but the output gives back only the one value. Any idea how to do that?
string <- "<td>VALUE1<td>VALUE2<td>"
regmatches(string , gregexpr("(?<=<td>)\\w+(?=<td>)" , string , perl = T) )
# use gregexpr function to get the match indices and the lengthes
indices <- gregexpr("(?<=<td>)\\w+(?=<td>)" , string , perl = T)
# this should be the result
# [1] 5 15
# attr(,"match.length")
# this means you have two matches the first one starts at index 5 and the
#second match starts at index 15
#[1] 6 6
#attr(,"useBytes")
# this means the first match should be with length 6 , also in this case the
#second match with length of 6
# then get the result of this match and pass it to regmatches function to
# substring your string at these indices
regmatches(string , indices)
Did you take a look at the "XML" package that can extract tables from HTML? You probably need to provide more context of the entire message that you are trying to parse so that we could see if it might be appropriate.
I am trying to change the name of some columns in my data using str_c function ( after installing "stringr" package). Column names are as follow:
> x
a b c d
I need to change the the "c" and "d" with "Aa" and "Ab". So instead of writing the full column names in my command, I will use the following structure:
colnames(x[,3:4])<-str_c(colnames(x[,1:2], "A")
However, the result shows the "A" at the end not the beginning of the name. So how to put the "A" at the beginning to get the following:
> x
a b Aa Ab
If I understand your question and this is for displaying a "column name", then you should swap the order in your expression, this
colnames(x[,3:4])<-str_c(colnames(x[,1:2], "A")
should be
colnames(x[,3:4])<-str_c("A", colnames(x[,1:2])
Note column names with a leading digit won't work with the $ function unless the name is quoted. So "A" works fine with '$' function but "1" needs the name to be quoted.