Using with() to simply your object operations in R

We provide effective and economically affordable training courses for R and Python, click here for more details and course registration !

with() function in R provides an alternative way of carrying out several operations bypassing inputting object name repeatedly. For example, we have a data frame ‘grade’ on hand, and want to calculate the correlation coefficient between Math and Physics variables and show summary statistics of numerical variables, we can write code as follows:

#show first observations of data frame
head(grade)
#output
  StudentID        Fullname Race Gender Country Age Math Physics
1         1     James Zhang    A   Male      US  23   73      70
2         2       Wilson Li    E Female      UK  26   95      76
3         3 Richard Nuan Ye    A   Male      UK  35   77      83
4         4       Mary Deng    E Female      US  21   60      99
5         5    Jason Wilson    A   Male      UK  19   77      89
6         6 Jennifer Hopkin    A Female      UK  43   79      64
  Chemistry       Date
1        87 10/31/2008
2        83  3/16/2008
3        92  5/22/2008
4        84  1/24/2009
5        93  7/30/2009
6        83   4/5/2009
#show summary statistics of Math variable
summary(grade$Math)
#result
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   60.0    72.5    79.0    78.9    87.0    95.0 
#correlation between Math and Physics grades
> cor(grade$Math,grade$Physics)
#result
[1] -0.04852046

If we use with, all the relevant codes will be packed into a with() block, and object name ‘grade’ are therefore ommited.

#Using with block to do same operations
with(grade, {
  print(summary(Math))
  print(cor(Math, Physics))
})
#result
Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   60.0    72.5    79.0    78.9    87.0    95.0 
[1] -0.04852046

Just note the objects created inside the with() block usually exist only in it. So if you want to call this object outside of with() block, it does not exist.

#object assignments exist only within the function brackets
with(grade, {
  test <- summary(Math)
  test
})
#not work if we refer to the object created inside with()
test
#output
Error: object 'test' not found

If you want to bypass this limit, you can use instead a double arrow assignment symbol inside the with() block.

#use special assignment operator (<<-) to bypass the local scope limit
with(grade, {
  summary(Math)
  cor(Math,Physics)
  test<<- summary(Math)
})
test
#output
Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   60.0    72.5    79.0    78.9    87.0    95.0 
#Then we can use same technique for updating grade data frame
with(grade, {
  grade$totalscore <- Math + Physics + Chemistry
  print(grade$totalscore)
  grade <<- grade
})
#show first observations of data frame, and it works
head(grade)
#output
  StudentID        Fullname Race Gender Country Age Math Physics
1         1     James Zhang    A   Male      US  23   73      70
2         2       Wilson Li    E Female      UK  26   95      76
3         3 Richard Nuan Ye    A   Male      UK  35   77      83
4         4       Mary Deng    E Female      US  21   60      99
5         5    Jason Wilson    A   Male      UK  19   77      89
6         6 Jennifer Hopkin    A Female      UK  43   79      64
  Chemistry       Date totalscore
1        87 10/31/2008        230
2        83  3/16/2008        254
3        92  5/22/2008        252
4        84  1/24/2009        243
5        93  7/30/2009        259
6        83   4/5/2009        226

For getting more knowledge of R and a preview of our training course, you can watch R tutorial videos on our YouTube channel !