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I have a data frame with several variables. What I want is create a string using (concatenation) the variable names but with something else in between them...
Here is a simplified example (number of variables reduced to only 3 whereas I have actually many)
Making up some data frame
df1 <- data.frame(1,2,3) # A one row data frame
names(df1) <- c('Location1','Location2','Location3')
Actual code...
len1 <- ncol(df1)
string1 <- 'The locations that we are considering are'
for(i in 1:(len1-1)) string1 <- c(string1,paste(names(df1[i]),sep=','))
string1 <- c(string1,'and',paste(names(df1[len1]),'.'))
string1
This gives...
[1] "The locations that we are considering are"
[2] "Location1"
[3] "Location2"
[4] "Location3 ."
But I want
The locations that we are considering are Location1, Location2 and Location3.
I am sure there is a much simpler method which some of you would know... Thank you for you time...
422
Concatenation is the process of combining two or more strings to form a new string by subsequently appending the next string to the end of the previous strings. In Java, two strings can be concatenated by using the + or += operator, or through the concat() method, defined in the java. lang. String class.
In formal language theory and computer programming, string concatenation is the operation of joining character strings end-to-end. For example, the concatenation of "snow" and "ball" is "snowball".
C++ has a built-in method to concatenate strings. The strcat() method is used to concatenate strings in C++. The strcat() function takes char array as input and then concatenates the input values passed to the function. In the above example, we have declared two char arrays mainly str1 and str2 of size 100 characters.
The concatenation of strings is a process of combining two strings to form a single string. If there are two strings, then the second string is added at the end of the first string. We can concatenate the strings in the following three ways: Concatenate two strings using loop.
The fact that these are names of a data.frame does not really matter, so I've pulled that part out and assigned them to a variable strs.
strs <- names(df1)
len1 <- length(strs)
string1 <- paste("The locations that we are considering are ",
paste(strs[-len1], collapse=", ", sep=""),
" and ",
strs[len1],
".\n",
sep="")
This gives
> cat(string1)
The locations that we are considering are Location1, Location2 and Location3.
Note that this will not give sensible English if there is only 1 element in strs.
The idea is to collapse all but the last string with comma-space between them, and then paste that together with the boilerplate text and the last string.
151
Are you looking for the collapse argument of paste?
> paste (letters [1:3], collapse = " and ")
[1] "a and b and c"
If your main goal is to print the results to the screen (or other output) then use the cat function (whose name derives from concatenate):
> cat(names(iris), sep=' and '); cat('\n')
Sepal.Length and Sepal.Width and Petal.Length and Petal.Width and Species
If you need a variable with the string, then you can use paste with the collapse argument. The sprintf function can also be useful for inserting strings into other strings (or numbers into strings).
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