CODEWITHSUNDEEP
rvariablesreference
random_walker
random_walker

Reputation: 11

sum() operation on a data frame using variable reference

I have 2 data frames.

  1. msf has 2 rows and few hundred columns, each column head being a stock name and consisting all numerical elements.
  2. currList has many rows each of which has a stock name.

msf:-

  s1 s2 s3 s4 s5 s6 
 1 0  1  0  0  1  0  
 2 0  0  1  0  1  0

currList:- 

 1 s2
 2 s4
 3 s5
 4 s7

I want to find the column sum of msf for each stock in currList. I tried this: 

for curr in 1:nrow(currList){ 
    currSum<- sum(paste("msf$",curr, sep=""))
    ....    
    }

It gave an error as:

Error in sum(paste("msf$", curr, sep = "")) : 
  invalid 'type' (character) of argument

I am new to programming and R and need help to achieve what I want.

Upvotes: 0

Views: 49

Answers (1)

won782
won782

Reputation: 721

Your question is bit unclear but assuming my understanding is correct, it can be solved as followings :

data = data.frame(t(sample(50, 10)))
data
  X1 X2 X3 X4 X5 X6 X7 X8 X9 X10
 1 36  8 24 47  3 33 44  7 45  21

currlist = data.frame(c("X1", "X5", "X6"))
colnames(currlist) = "stocks"
currlist
   stocks
1     X1
2     X5
3     X6 

rowSums(data[ ,colnames(data) %in% currlist$stocks])

However all of above is not standard / effective way of storing and processing data. You can go over basic data structure and manipultation techniques for the better understanding.

Upvotes: 1

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