How to solve this error of conditional statements and Loops in R? - r

You can suggest me any sort of answers, not necessarily need using conditional statements and Loops.
I have the data set with several ids and and three alert or groups.
here is the image for the concept:
and here is the actual Data set for one ID: Click me
Concept is:
I have three alert: Relearn - Rebuild - Replace.
and after relearn: rebuild or replace can come but relearn cannot come
and after rebuild: replace can come but relearn cannot come
after replace: relearn and rebuild cannot come. if there is any replace only that can come
I have attached the image and Dataset for better clear understanding and Here is my try:
temp1 = NULL
temp2 = NULL
sql50 = NULL
for(i in 1:nrow(BrokenPins)) #First Loop
{
sql50 = sqldf(paste("select * from rule_data where key = '",BrokenPins[i,1],"'",sep = ""))
for(j in 1:nrow(sql50))
{ #Second Loop
while (head(sql50$Flag,1) == sql50$Flag[j] )
{
temp1 = sql50[j,]
temp2 = rbind(temp2,temp1)
print("Send")
if(j == 1 || sql50$Flag[j] == sql50$Flag[j-1])
{
j = j+1
}
else(sql50$Flag[j] > sql50$Flag[j-1])
{
break
}
}
}
}
First loop will go through each id and second loop will give me all the alert for that id.
so in the image i have added send and dont send. it wont be in actual table. that basically means send means copy it to new dataframe like i am doing above rbind in the code and dont send means dont copy it. This Above piece of code will run but only take the first and end it.
Finally, Based On above Data set Click me: that is for one ID (key), Flag (1 - Relearn, 2-Rebuild,3-replace). so based on this dataset. my output should have Row 1, 2 and 7 because First Relearn[Flag 1] came then Rebuild[Flag 2] then again relearn[Flag 1]cannot come, only rebuild [Flag 2] and replace[Flag 2] can.
can you help me solve this concept?

One thing I notice is that you use else and also provided a condition; you should only use else when you want every case that is not included in the condition of your if statement. Basically, instead of using else(sql50$Flag[j] > sql50$Flag[j-1]) you should be using else if(sql50$Flag[j] > sql50$Flag[j-1]).

Related

Length Zero in r

Greetings I am getting an error of
Error in if (nrow(pair) == 0) { :argument is of length zero
I have checked the other answers but do not seem to work on a variable like mine. Please check code below, please assist if you can.
pair<-NULL
if(exists("p.doa.ym")) pair <- rbind(pair, p.doa.ym[,1:2])
if(exists("p.doa.yd")) pair <- rbind(pair, p.doa.yd[,1:2])
if(nrow(pair) == 0) {
print("THERE ARE NO MATCHES FOR TODAY. STOP HERE")
quit()
}
Since you set pair=NULL and then it might happen that pair stays null if those two if statements are not true, you either need to check if pair is null first, or you could set pair to an empty data frame, or something else.
One option:
if (!is.null(pair)) {
if (nrow(pair)==0) {
# your code
}
}
Another option:
pair=data.frame()
# your code

Need to Print Value of a Variable using Paste in R

I am trying to create a data frame of various error messages based on Data to be cross checked between two dataframes and storing the message in a vector in an iterative manner . I am using the following snippet for this purpose :
> for(j in 1:nrow(MySQL_Data)){ date_mysql=
> paste("MySQL_Data[",j,",1]") date_red= paste("RED_Data[",j,",1]")
> body= c() if(!date_mysql == date_red) {
> body<- append(body,paste("'There is data missing for date",date_mysql,"in",table2)) }else {
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My table2 variable prints as MYSQL_Data[2,1] instead of the actual value of the variable which is a date
Following is the Output :
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Can someone help me with the error that I am committing here..
Thanks in Advance !
Your use of paste in the definitions of data_mysql and data_red makes no sense. I’m assuming that what you actually want is this:
data_mysql = MySQL_Data[j, 1]
data_red = RED_Data[j, i]
Furthermore, you’re resetting body in every loop iteration so it will only ever hold a single element.

R: Iterating Over the List

I am trying to implement following algorithm in R:
Iterate(Cell: top)
While (top != null)
Print top.Value
top = top.Next
End While
End Iterate
Basically, given a list, the algorithm should break as soon as it hits 'null' even when the list is not over.
myls<-list('africa','america south','asia','antarctica','australasia',NULL,'europe','america north')
I had to add a for loop for using is.null() function, but following code is disaster and I need your help to fix it.
Cell <- function(top) {
#This algorithm examines every cell in the linked list, so if the list contains N cells,
#it has run time O(N).
for (i in 1:length(top)){
while(is.null(top[[i]]) !=TRUE){
print(top)
top = next(top)
}
}
}
You may run this function using:
Cell(myls)
You were close but there is no need to use for(...) in this
construction.
Cell <- function(top){
i = 1
while(i <= length(top) && !is.null(top[[i]])){
print(top[[i]])
i = i + 1
}
}
As you see I've added one extra condition to the while loop: i <= length(top) this is to make sure you don't go beyond the length of the
list in case there no null items.
However you can use a for loop with this construction:
Cell <- function(top){
for(i in 1:length(top)){
if(is.null(top[[i]])) break
print(top[[i]])
}
}
Alternatively you can use this code without a for/while construction:
myls[1:(which(sapply(myls, is.null))[1]-1)]
Check this out: It runs one by one for all the values in myls and prints them but If it encounters NULL value it breaks.
for (val in myls) {
if (is.null(val)){
break
}
print(val)
}
Let me know in case of any query.

R code does not work when called from function

HI i just started learning R and finding this problem to be really interesting where I just run a code directly without wrapping in a function it works but when I place it inside a function it doesn't work, What can be possible reason?
fill_column<-function(colName){
count <- 0
for(i in fg_data$particulars) {
count <- count +1
if(grepl(colName, i) && fg_data$value[count] > 0.0){
fg_data[,colName][count] <- as.numeric(fg_data$value[count])
} else {
fg_data[,colName][count] <- 'NA'
}
}
}
fill_column('volume')
Where I am creating new column named volume it this string exists in particulars column.
I have added a comment where solution given by another question does not work for me, Please look at my comment below.
Finally I got it working but reading another answer on SO, here is the solution:
fill_column <- function(colName){
count <- 0
for(i in fg_data$particulars) {
count <- count +1
if(grepl(colName, i) && fg_data$value[count] > 0.0){
fg_data[,colName][count] <- as.numeric(fg_data$value[count])
} else {
fg_data[,colName][count] <- 'NA'
}
}
return(fg_data)
}
fg_data = fill_column('volume')
Now reason, Usually in any language when we modify global object inside any function it reflects on global object immediately but in R we have to return the modified object from function and then assign it again to global object to see our changes. or another way for doing this is to assign local object from within the function to global context using envir=.GlobalEnv.

If inside of double loop

Inside of double loop I create subset of data for each combination of Tv stations with months which is done by loops. For example I have monthsnumbers 7,8,9 and stations A,B,C. It happens that for Month 9 there is no station C.
Then subset is empty and function throws and error of no possible aggregation.
So as you can see I tried to use if statement that if there are 0 rows don't continue with the code but go on to the next loop.
But I still get the same error fck. message
can you please navigate me ?
for (Mesic in monthnumbers){
for (Stanica in TVstations){
Client<-data[data$month ==Mesic & data$Channel_group1 ==Stanica & data$Brand == brand, ]
if (nrow(Client)!=0)
###some code
Client_AGG<-aggregate(formula= Client$BUYING_GRPs ~ Client$Brand,data= Client,FUN = sum)
###some code
}
}
}
Like Gregor commented, there is likely a better way of going about this.
But a quick patch might be to put the error check before the Client<- line because that's where it's looking for a channel that doesn't exist. Check if data$Channel_group1 == Stanica even exists before trying to get data from it.
Another option using for loops is to cycle through what you know is there with something like this:
subsetindex <- unique(data[ ,c('month','Channel_group1')])
for(i in 1:nrow(subsetindex)){
Client<-data[data$month ==subsetindex[i,'month'] & data$Channel_group1 ==subsetindex[i,'Channel_group1'] & data$Brand == brand, ]
#other code
}

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