The file is very large so I cannot store in memory. I iterate line by line as follows
for (line <- Source.fromFile(file).getLines) {
}
How can I specify that the first line should be skipped?
How about:
for (line <- Source.fromFile(file).getLines.drop(1)) {
// ...
}
drop will simply advance the iterator (returned by getLines) past the specified number of elements.
Related
I have sample file record like this
2018-01-1509.05.540000000000001000000751111EMAIL#AAA.BB.CL
and the above record is from a fixed length file and I wanted to split based on the lengths
and when I split I am getting a list as shown below.
ListBuffer(2018-01-15, 09.05.54, 00000000000010000007, 5, 1111, EMAIL#AAA.BB.CL)
Everything looks fine until now . But I am not sure why is there extra-space adding in each field in the list(not for the first field).
Example : My data is "09.05.54",But I am getting as" 09.05.54" in the list.
My Logic for splitting is shown below
// Logic to Split the Line based on the lengths
def splitLineBasedOnLengths(line: String, lengths: List[String]): ListBuffer[Any] = {
var splittedLine = line
var split = new ListBuffer[Any]()
for (i <- lengths) yield {
var c = i.toInt
var fi = splittedLine.take(c)
split += fi
splittedLine = splittedLine.drop(c)
}
split
}
The above code take's the line and list[String] which are nothing but lengths as input and gives the listbuffer[Any] which has the lines split according to the length.
Can any one help me why am I getting extra space before each field after splitting ?
There are no extra spaces in the data. It's just adding some separation between the elements when printing them (using toString) to make them easier to read.
To prove this try the following code:
split.foreach(s => println(s"\"$s\""))
You will see the following printed:
"2018-01-15"
"09.05.54"
"00000000000010000007"
"5"
"1111"
"EMAIL#AAA.BB.CL"
I was able to remove the first few lines of a single file using the code below:
scala> val file = sc.textFile("file:///root/path/file.csv")
Removing first 5 lines:
scala> val Data = file.mapPartitionsWithIndex{ (idx, iter) => if (idx == 0) iter.drop(5) else iter }
The problem is: Suppose that I have multiple files with the same columns, and I want to load all of them into rdd, removing the first few lines of each file.
Is this actually possible?
I'd appreciate any help. Thanks in advance!
Lets assume there are 2 files.
ravis-MacBook-Pro:files raviramadoss$ cat file.csv
first_file_first_record
first_file_second_record
first_file_third_record
first_file_fourth_record
first_file_fifth_record
first_file_sixth_record
ravis-MacBook-Pro:files raviramadoss$ cat file_2.csv
second_file_first_record
second_file_second_record
second_file_third_record
second_file_fourth_record
second_file_fifth_record
second_file_sixth_record
second_file_seventh_record
second_file_eight_record
Scala Code
sc.wholeTextFiles("/Users/raviramadoss/files").flatMap( _._2.lines.drop(5) ).collect()
Output:
res41: Array[String] = Array(first_file_sixth_record, second_file_sixth_record, second_file_seventh_record, second_file_eight_record)
In Spark/Hadoop if you give the input path as the directory containing all the files then the code which you have written will work on all the individual files separately.
So to achieve your objective, just give the input path as the directory containing all the files. So the first few lines will be removed from all the files.
As I am new to scala ,This problem might look very basic to all..
I have a file called data.txt which contains like below:
xxx.lss.yyy23.com-->mailuogwprd23.lss.com,Hub,12689,14.98904563,1549
xxx.lss.yyy33.com-->mailusrhubprd33.lss.com,Outbound,72996,1.673717588,1949
xxx.lss.yyy33.com-->mailuogwprd33.lss.com,Hub,12133,14.9381027,664
xxx.lss.yyy53.com-->mailusrhubprd53.lss.com,Outbound,72996,1.673717588,3071
I want to split the line and find the records depending upon the numbers in xxx.lss.yyy23.com
val data = io.Source.fromFile("data.txt").getLines().map { x => (x.split("-->"))}.map { r => r(0) }.mkString("\n")
which gives me
xxx.lss.yyy23.com
xxx.lss.yyy33.com
xxx.lss.yyy33.com
xxx.lss.yyy53.com
This is what I am trying to count the exact value...
data.count { x => x.contains("33")}
How do I get the count of records who does not contain 33...
The following will give you the number of lines that contain "33":
data.split("\n").count(a => a.contains("33"))
The reason what you have above isn't working is that you need to split data into an array of strings again. Your previous statement actually concatenates the result into a single string using newline as a separator using mkstring, so you can't really run collection operations like count on it.
The following will work for getting the lines that do not contain "33":
data.split("\n").count(a => !a.contains("33"))
You simply need to negate the contains operation in this case.
I'm looking for the best way to process a file in which, based on the contents, i combine certain lines into XML and return the XML.
e.g. Given
line 1
line 2
line 3
line 4
line 5
I may want the first call to return
<msg>line 1, line 2</msg>
and a subsequent call to return
<msg>line 5, line 4</msg>
skipping line 3 for uninteresting content and exhausting the input stream. (Note: the <msg> tags will always contain contiguous lines but the number and organization of those lines in the XML will vary.) If you'd like some criteria for choosing lines to include in a message, assume odd line #s combine with the following four lines, even line #s combine with the following two lines, mod(10) line #s combine with the following five lines, skip lines that start with '#'.
I was thinking I should implement this as an iterator so i can just do
<root>{ for (m <- messages(inputstream)) yield m }</root>
Is that reasonable? If so, how best to implement it? If not, how best to implement it? :)
Thanks
This answer provided my solution: How do you return an Iterator in Scala?
I tried the following but there appears to be some sort of buffer issue and lines are skipped between calls to Log.next.
class Log(filename:String) {
val src = io.Source.fromFile(filename)
var node:Node = null
def iterator = new Iterator[Node] {
def hasNext:Boolean = {
for (line <- src.getLines()) {
// ... do stuff ...
if (null != node) return true
}
src.close()
false
}
def next = node
}
There might be a more Scala-way to do it and i'd like to see it but this is my solution to move forward for now.
Reading lines in a foreach loop, a function looks for a value by a key in a CSV-like structured text file. After a specific line is found, it is senseless to continue reading lines looking for something there. How to stop as there is no break statement in Scala?
Scala's Source class is lazy. You can read chars or lines using takeWhile or dropWhile and the iteration over the input need not proceed farther than required.
To expand on Randall's answer. For instance if the key is in the first column:
val src = Source.fromFile("/etc/passwd")
val iter = src.getLines().map(_.split(":"))
// print the uid for Guest
iter.find(_(0) == "Guest") foreach (a => println(a(2)))
// the rest of iter is not processed
src.close()
Previous answers assumed that you want to read lines from a file, I assume that you want a way to break for-loop by demand.
Here is solution
You can do like this:
breakable {
for (...) {
if (...) break
}
}