I'm trying to remove the row names for all of my data using a for loop to make it shorter, but It is creating a new value called "i" rather than removing the rownames
this is the example of my code where U91, etc are my data.
for (i in c(U91,P95,P98,E10)) {
rownames(i) <- NULL
}
I have also tried using quotations inside the c() and still an error this instead creates an i value of "E10"
Another Problem I'm having with is trying to loop this function:
Caltex <- Main[Fuel=="Caltex", ]
for (i in c("7-Eleven","Caltex","Indie")) {
i <- Main[Brand==i, ]
}
rownames(dataframe) returns 'string' of vector. So, if want to remove or to do any operation of 'rownames' try to create a vector of string.
for example:
c("U91","P95","P98","E10") and then 'rownames(i) <- NULL'
to answer your second question: Please remember you are handling string. String does not work the same way it works for numbers.
Please explain your second question elaborately about your variables and string input. So, that I could help on this.
Related
I have a list of items that would like to check my field titled 'events' for. my desired output is another field in the table for each item in my list, which contains a count of that item for each row. I have little experience writing for loops and am stuck, but below is the logic of what I'm looking for.
events <- c('screen_view','cta','os_update')
for (i in events) {
event_data_consumer$i <- str_count(event_data_consumer$event,'i')
}
Does anyone know of a way to do this? Possibly in apply/lapply etc ?
The for loop code had two issues - 1) $i - will literally create a column i instead of the value from for each loop. Here, we can use [[. 2) 'i' will again be taken string "i" instead of the value, so we don't need a quoted value
library(stringr)
for(i in events) {
event_data_consumer[[i]] <- str_count(event_data_consumer$event, i)
}
Or with lapply, loop over the vector of events with lapply, get the count of strings from the 'event' column and assign it to new columns in the data with [
event_data_consumer[events] <- lapply(events, function(x)
str_count(event_data_consumer$event, x))
So this is a bit strange, I am pretty new to R and facing this weird problem.
I have a data frame, and there is a column called SNDATE which is a combined value of two different columns.
I want to check if the data frame has a column named SN, if it doesn't I will split SNDATE to fill the SN column.
Here is the code
if(!('SN' %in% colnames(data))){
#do some spliting here
}
Funny thing is, it keeps saying it's there, and the stuff in it never gets triggered.
And when I do this:
print(data$SN)
It will print the value of data$SNDATE. So does R have some sort of lazy name filling or something? This is very strange to me.
Thank you very much for the help
When you do
print(data$SN)
it works because $ is using partial name matching. For another example, try
mtcars$m
There is no column named m, so $ partially matches mpg. Unfortunately, this is not used in %in%, so you will need to use the complete exact column name in
if(!('SNDATE' %in% colnames(data))){
#do some spliting here
}
You could insead use something along the lines of pmatch()
names(mtcars)[2] <- "SNDATE"
names(mtcars)[pmatch("SN", names(mtcars))]
# [1] "SNDATE"
So the if() statement might go something like this -
nm <- colnames(data)
if(!nm[pmatch("SN", nm)] %in% nm) {
...
}
Or even
if(is.na(pmatch("SN", names(data)))
might be better
I have the below function which inserts a row into a table (new_scores) based upon the attribute that I feed into it (where the attribute represents a table that I select things from):
buildNewScore <- function(x) {
something <- bind_rows(new_scores,x%>%select(ATT,ADJLOGSCORE))
return(something)
}
Which works fine when I define x.
But when I try to create a for loop that feeds the rest of my attributes into the function it falls over as I'm feeding in a character.
attlist <- c('Z','Y','X','W','V','U','T','RT','RO')
record_count <- length(attlist)
for (x in c(1:record_count)){
buildNewScore(attlist[x])
}
I've tried to convert the attribute into other classes but I can't get the loop to use anything I change it to (name, data.frame etc.).
Anyone have any ideas as to where I'm going wrong - is my attlist vector in the wrong format?
Thanks,
Spikelete.
I have stored a list of names as characters and want to convert them to something that can be accepted as data frame name. something like this:
for (i in 1:18) {
str[i] <- paste("alert_month_amount_",i,sep="")
}
name_str = as.character(str)
then name_str will be:
name_str[1] would be "alert_month_amount_1"
now i want to assign certain data to a data frame that uses name_str[i] inside a loop like:
for (n in 1:18){
name_str[n] <- subset(by_Month_Acct_Num,month==month_index[n] & year==year_index[n])
}
but this does not work perhaps because the names are passed as characters inside double quotation mark ("). I would appreciate your help.
You can use assign for this:
assign(name_str[n], subset(by_Month_Acct_Num,month==month_index[n] & year==year_index[n]))
This is FAQ 7.21. The most important part of that answer is the end where it says (like #MrFlick) that it is better to use a list. You really should learn how to take advantage of R's vectorized functions.
The paste and paste0 functions are both vectorized, so your first bit of code can be replaced with:
name_str <- paste0("alert_month_amount_", 1:18)
without need for the loop.
You could create your list and fill it with code like:
alert_month_amount <- list()
for(i in 1:18) {
alert_month_amount[[i]] <- subset(by_Month_Acct_Num,month==month_index[n] & year==year_index[n])
}
Or possibly even easier using the split function. You could also use lapply or mapply.
If you want the elements named then just do:
names(alert_month_amount) <- name_str
Now with everything in a single list you can copy, save, delete, etc. one object rather than needing another loop to do each individual piece. If you want to do the same thing (calculate a summary, fit a regression, etc.) on each piece created then with everything in a list you can just use lapply or sapply on the list rather than having to create another loop and figuring out how to grab each piece in the loop and save it to an output object.
I'm working on a function and need to know how to reference the incoming parameters.
For example, in python or lots of other languages, you can reference the input parameters something like this:
sys.argv[1:].
How can I reference the name of a parameter in R?
The specific problem I'm trying to solve is I want to capture the string value of the incoming parameter, so I can paste it as a concentration with a list of column_names I want to iterate through.
Here's the head of the function call, just so you can see the incoming parameter:
function(df_in)
So here's an example of the code I am writing and I want the string value of the dataframe_in, not the object that it references.
col_name <-paste(df_in,varnames[i],sep="$")
if df_in contained "my_df" and the current column_name is my_col, I'm trying to have col_name in the example above set to my_df$my_col.
I was thinking of using the get() function but quite sure how to apply it in this situation.
Thanks
Try something along these lines:
fn1 <- function(df_in){ in_nam <- deparse(substitute(df_in) )
col_names <-paste(in_nam, names(df_in), sep="$")
cat(col_names) }
> dfrm <- data.frame(a=1:10, b=letters[1:10])
> fn1(dfrm)
#dfrm$a dfrm$b
You didn't say what varnames was supposed to be so I'm guessing you want the column names from the object. BTW, don't expect to be able to reference the column values with those character values. They are no longer language objects.