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How to Solve R Error in readchar(con, 5l, usebytes = true) : cannot open the connection

by | Programming, R, Tips

In R, if you try to load a file that does not exist using load() function, you will raise the error Error in readchar(con, 5l, usebytes = true) : cannot open the connection.

To solve this error you need to check that the file exists and that the spelling you used for the filename is correct.

This tutorial will go through the error and how to solve it with code examples.

Table of contents

Example

Let’s look at an example of a data frame with two columns.

dat1 <- data.frame(x=c("A", "B", "C", "D"),
  vals = c(2, 4, 6, 8))

dat1
  x vals
1 A    2
2 B    4
3 C    6
4 D    8

Next, we will save the data frame to an R Data File (RDA).

save(dat1, "test1.rda")

Now in a new session, we will try to load the .RDA file using load()

load("dat.rda")

Let’s run the code to see what happens:

Error in readChar(con, 5L, useBytes = TRUE) : cannot open the connection
In addition: Warning message:
In readChar(con, 5L, useBytes = TRUE) :
  cannot open compressed file 'dat.rda', probable reason 'No such file or directory'

The error occurs because the file dat.rda does not exist in the directory.

Solution

We can check if the file exists and the correct name using list.files()

list.files()
"data.rda"

We can see that the file is called data.rda not dat.rda. Let’s try to load data.rda into our program:

load("data.rda")
dat1

Let’s run the code to see the result:

  x vals
1 A    2
2 B    4
3 C    6
4 D    8

We successfully loaded the data frame into the program.

Summary

Congratulations on reading to the end of this tutorial!

For further reading on R related errors, go to the articles: 

Go to the online courses page on R to learn more about coding in R for data science and machine learning.

Have fun and happy researching!