R: Applying a function to every entry in dataframe

Question

I want to make every element in the dataframe (except fot the ID column) become a 0 if it is any number other than 1.

I have:

ID  A B C D E
abc 5 3 1 4 1
def 4 1 3 2 5

I want:

ID  A B C D E
abc 0 0 1 0 1
def 0 1 0 0 0

I am having trouble figuring out how to specify for this to be done to do to every entry in every column and row.

Here is my code:

apply(dat.lec, 2 , function(y) 
  if(!is.na(y)){
      if(y==1){y <- 1}
      else{y <-0} 
     }
  else {y<- NA}
)

Thank you for your help!

Have you tried using apply over columns and rows by setting MARGIN = c(1,2)? You could do that for dat.lec[ ,-1] to exclude the ID column. — missng
– missng, Commented Nov 16, 2017 at 21:56

Maurits Evers · Accepted Answer · 2017-11-16 22:37:51Z

2

No need for implicit or explicit looping.

# Sample data
set.seed(2016);
df <- as.data.frame(matrix(sample(10, replace = TRUE), nrow = 2));
df <- cbind.data.frame(id = sample(letters, 2), df);
df;
#  id V1 V2 V3 V4 V5
#1  k  2  9  5  7  1
#2  g  2  2  2  9  1    

# Replace all entries != 1 with 0's
df[, -1][df[, -1] != 1] <- 0;
df;
#  id V1 V2 V3 V4 V5
#1  k  0  0  0  0  1
#2  g  0  0  0  0  1

edited Nov 16, 2017 at 22:37

answered Nov 16, 2017 at 21:56

Maurits Evers

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2 Comments

Katy Torres Over a year ago

This works great but it also gets rid of all my Id's in column 1, how can I have the first column remain the same?

Maurits Evers Over a year ago

@KatyTorres Please see my updated answer. If you have additional ID columns, just exclude them when replacing entries.

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