Explore our sites

Stack Exchange
tour help careers 2.0
Take the 2-minute tour ×
Stack Overflow is a question and answer site for professional and enthusiast programmers. It's 100% free, no registration required.
up vote 1 down vote favorite

I have a file arranged like so:
"url1","info1"
"url2","info2"
"url3","info3" ... all the way up to "url15","info15"

I would like to read the last 10 lines of the file into an array such that $pagelist[0][0] would give url5 and $pagelist[0][1] would give info5.

My current code is as follows:

$file=fopen(csvfile.txt,"r");
$pagelist=array();
$i=0;
$key=0;
while (!feof($file)) {
    if ($i >= (count($file)-11)) {
        $pagelist[$key]=fgetcsv($file);
        $key++; }
    $i++;
}
fclose($file)

When I used print_r($pagelist) it seemed to have loaded all the lines of the file into the array instead of just the last 10. Can anyone see what I've done wrong in my code? thanks :)

share|improve this question
add comment

3 Answers

up vote 3 down vote accepted

The problem with you code is that count($file) is not doing what you think. $file is just a file handle resource, not an array. You end up comparing $i >= -11, which will of course always evaluate to true/

You might try something like this if you want to just use linux to grab the last ten lines (not sure if you are on linux):

$initial_csv = 'csvfile.txt';
$truncated_csv ='csvfile_trun';
$number_of_lines_from_from_end = 10;
shell_exec('tail -n ' . $number_of_lines_from_end . ' ' . $initial_csv . ' > ' . $truncated_csv);
$file=fopen($truncated_csv,"r");
$pagelist=array();
$i=0;
while (!feof($file)) {
    $pagelist[$i]=fgetcsv($file);
    $i++;
}
fclose($file)

Alternateively, if you don't mind having the entire file in memory (i.e. the file will remain small), you can read the entire file into an array like this.

$csv = 'csvfile.txt';
$number_of_lines_from_from_end = 10;
$file_array = file($csv);
$line_count = count($file_array);
$start = $line_count - $number_of_lines_from_from_end - 1;
$pagelist=array();
for ($i = $start; $i < $line_count; $i++) {
    $pagelist[]=fgetcsv($file);
}
share|improve this answer
 
If going the file() route (huge memory indeed), an foreach(array_slice($file_array,$line_count-11,10) as $line) $pagelist[]=str_getcsv($line); seems more apt. –  Wrikken Dec 15 '12 at 0:17
1  
@Wrikken The only reason I provided the file() solution is that it seems the OP is dealing with relatively little data. If you were talking about thousands of line of data, I would use something like the linux tail command to solution to just get the portion of the data is cared about right up front. You are right that array_slice() would work fine just as well. –  Mike Brant Dec 15 '12 at 0:23
 
Just to clarify, the array_slice doesn't address the memory issue; the use of file() means that the file is already read into memory. array_slice just avoids looping through the first n-10 lines. –  ernie Dec 15 '12 at 0:25
 
@ernie You are correct about the memory consumption. The code shown does not loop through the first n-10 lines, however. –  Mike Brant Dec 15 '12 at 0:32
 
Yes, I wouldn't advocate file() for a couple of MBs of logfiles for instance, I was just saying that if we have it, we might as well use it (and your code misses a seeking to the proper line in that part b.t.w.). If I was the OP, I'd go for the tail solution most definitely (with proper escapeshellarg for dynamic arguments). –  Wrikken Dec 15 '12 at 0:37
show 3 more comments
up vote 0 down vote

Yet another implementation, for the fun of it (Mike's tail is probably fastest):

$storage  = new SPLFixedArray(10);
$i = 0;
while(($line = fgets($file)) && ++$i) {
    $storage[$i%10] = $line;
}
$storage = $storage->toArray();
//switch if order is important;
$prepend = array_splice($storage,($i%10)+1,10 - ($i%10));
array_splice($storage,0,0,$prepend);
//interpret csv
$result = array_map('str_getcsv',$storage);
share|improve this answer
 
FWIW, a simple 1M lines seems to take about 2 seconds here. Fast enough for shell scripts / crons, waaaaaay to long for HTTP requests. –  Wrikken Dec 15 '12 at 0:46
add comment
up vote -1 down vote 
$file=fopen(csvfile.txt,"r");    
$pagelist= [];                  
$temp = fgetcsv($file);          
array_merge($pagelist, $temp);   
fclose($file);                              
print_r($pagelist);                         
$lastten = array_slice($pagelist, -10, 10); 
print_r($lastten);

*I might be wrong about the slice offset and limit.

share|improve this answer
 
You need a loop for fgetcsv as it reads only a single line from the file. –  Mike Brant Dec 15 '12 at 0:24
 
Oops. Forgot about that. –  bobthyasian Dec 15 '12 at 0:31
1  
Thanks for the reply :) –  Sean Cooper Dec 15 '12 at 0:54
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.