A little exercise about a recent forum question input field handling in awk and Perl

A little exercise about a recent forum question input field handling in awk and Perl

Just recently the following question was posted to the UNIX scripting group in Linkedin:
remove all duplicate entries in a colon separated list of strings
e.g. a: b:c: b: d:a:a: b:e::f should be transformed to a: b:c: d:e::f

Some of the fields contain spaces which should be preserved in the output of course, there is an empty field too which (to me and other authors) indicates that the fields are not necessarily ordered. Here I wont discuss the suggested solutions, I also did not answer to the original posting because I read it one month too late.

awk
But when reading the question my brain already got working and I could not help to try for myself. The obvious tool of choice for exercises like this is awk because awk has inbuilt mechanisms for viewing lines as a sequence of fields with configurable field separators.

A solution could be

BEGIN {
  FS=":" ;    # field separator
  ORS=":"     # output record separator
}
{ for(i=1;i<=NF;i++) {  # for all input fields
    if( f[$i] ) {       # check if array entry for field already exists
     continue;          # if yes: go to next field
    } else {
     print $i;          # if no: print the field content
     f[$i] = 1;          # and record it in array f    }  }
}

which leads to this output:
a: b:c: d:e::f:

The script can be shortened by omitting superfluous braces and else to

BEGIN { FS=":" ; ORS=":" } 
{ for(i=1;i<=NF;i++) { if(f[$i]) continue; f[$i]=1; print $i; } } 

The script uses a very simple straightforward logic: loop through all input fields, if a field is new then print it, if not skip it. This is achieved by storing each field in an associated array f when it first occurs.
Using the field separator FS for splitting the input line and the output record separator ORS when printing (you need to know that print automatically adds ORS) makes this an easy task.

There is one issue though: this solution adds an extra colon at the very end (compared to the requested output), this could be an issue or not depending on the context of this request so one might prefer this code:

BEGIN { FS=":" } 
{ printf $1; f[$1]=1; 
  for(i=2;i<=NF;i++) { if(f[$i]) continue; f[$i]=1; printf FS $i } }

which uses a slightly different logic: the first field is printed straight away (and recorded), the loop checks the remaining fields 2..NF and prints the field separator as a prefix to the field content. This code also works for the extreme case where there is just one field and no colon.

Perl
I then wondered if this couldnt be done equivalently or even shorter in Perl but my best solution is a little bit lengthier because I have to use split to get the individual fields.

$FS=":";
@s = split($FS,<>);
for($i=0;$i<=$#s;$i++) {$e=$s[$i]; next if(exists($f{$e})); $f{$e}=1; print $e,$FS }

I could have used command line options "-a -F:" to avoid the split but I need FS to be defined anyway for the output (I dont know if the split pattern defined by -F can be accessed in Perl).
I use split to chop up the input line and put it into an array s. Then the same logic applies as in awk. Instead of an associative array Im using a hash table f in Perl. The variable e is only used to avoid repeated occurances of $s[$i]. In the end tits a matter of personal preference which solution you take.


It should be noted that I tested with

echo -n "...." | awk ... or perl -e ...

which feeds a string without newline to the pipe which helped to avoid chomp in Perl for removing the newline in the last field.

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5 Cool Recent Post Widgets for Blogger

5 Cool Recent Post Widgets for Blogger

For bloggers that pride themselves on always staying up-to-date with new content, a recent post widget for Blogger can be an invaluable tool. A recent post widget for blogger is in many ways similar to a breaking news alert that journalists love to use during their reports, providing the most recent and relevant posts that you have to offer.

Adding a recent post widget for Blogger helps to reduce the dependency on email marketing, because you dont have to send out an email just to let people know you made a new post. Instead, it updates automatically for everyone to see. You can then use this information to design scheduled email newsletters, and take advantage of whats often referred to as the Twitter effect where audiences will regularly check back on your site for the possibility that new posts are available. Without this, you force people to do run their own search for information and content, increasing the likelihood that theyll leave the site and hurt your bounce rate.

Once youve managed to attract visitors to one of your posts using the recent post widget for Blogger, it will continue to act as an accessible secondary resource to navigate around your site. That way, you can avoid having them sifting through old content that might be outdated. If youd rather show off some of your best posts instead of your most recent posts, you can do that instead, or add that feature to the bar with just a few alterations.

Apart from looking great and taking up minimal space, there are too many benefits for you not to have a recent post widget for Blogger. The best part about these add-ons is that they come in a wide variety of designs that will fit any theme. If youre interested in adding a widget to your site, here are 5 cool recent post widgets that might catch your eye and fit perfectly with your Blogger template:

Style #1

<script style="text/javascript" src="http://helplogger.googlecode.com/svn/trunk/helplogger/recentpoststhumbs.js"></script>
<script style="text/javascript">
var posts_no = 5;
var showpoststhumbs = true;
var readmorelink = true;
var showcommentslink = false;
var posts_date = true;
var post_summary = true;
var summary_chars = 70;
</script>
<script src="/feeds/posts/default?orderby=published&alt=json-in-script&callback=showlatestpostswiththumbs"></script>
<a style="font-size: 9px; color: #CECECE; float: right; margin: 5px;" href="http://softwareduck.blogspot.com/2015/05/5-cool-recent-post-widgets-for-blogger.html" rel="nofollow">Recent Posts Widget</a>
<noscript>Your browser does not support JavaScript!</noscript>
<link href=http://fonts.googleapis.com/css?family=Ubuntu+Condensed rel=stylesheet type=text/css />
<style type="text/css">
img.recent-post-thumb {width:50px;height:50px;float:right;margin: 5px -5px 0px 0px; border-radius: 100%; padding: 3px;background: #fff}
.recent-posts-container {font-family: Ubuntu Condensed, sans-serif; float: left;width: 100%;min-height: 55px;margin: 5px 0px 5px 0px;padding: 0;font-size:12px;}
ul.recent-posts-container {list-style-type: none; background: #fff;padding: 0px; }
ul.recent-posts-container li:nth-child(1n+0) {background: #F49A9A; width: 100%}
ul.recent-posts-container li:nth-child(2n+0) {background: #FCD092; width: 95%}
ul.recent-posts-container li:nth-child(3n+0) {background: #FFF59E; width: 90%;}
ul.recent-posts-container li:nth-child(4n+0) {background: #E1EFA0; width: 85%;}
ul.recent-posts-container li:nth-child(5n+0) {background: #B1DAEF; width: 80%;}
ul.recent-posts-container li {padding:5px 10px;min-height:50px; list-style-type: none; margin: 0px 5px -5px 5px; color: #777;}
.recent-posts-container a { text-decoration:none; }
.recent-posts-container a:hover { color: #222;}
.post-date {color:#e0c0c6; font-size: 11px; }
.recent-post-title a {font-size: 14px;color: #444; font-weight: bold;}
.recent-post-title {padding: 6px 0px;}
.recent-posts-details a{ color: #222;}
.recent-posts-details {padding: 5px 0px 5px; }
</style>

Style #2

<div class="recentpoststyle">
<script src="http://helplogger.googlecode.com/svn/trunk/helplogger/recentposts.js"></script>
<script>
var posts_no = 5;var posts_date = true;var post_summary = true;var summary_chars = 80;</script>
<script src="/feeds/posts/default?orderby=published&amp;alt=json-in-script&amp;callback=showlatestposts">
</script><a style="font-size: 9px; color: #CECECE; float: right; margin: 5px;" href="http://softwareduck.blogspot.com/2015/05/5-cool-recent-post-widgets-for-blogger.html" rel="nofollow">Recent Posts Widget</a>
<noscript>Your browser does not support JavaScript!</noscript>
<style type="text/css">
.recentpoststyle {counter-reset: countposts;list-style-type: none;}
.recentpoststyle a {text-decoration: none; color: #49A8D1;}
.recentpoststyle a:hover {color: #000;}
.recentpoststyle li:before {content: counter(countposts,decimal);counter-increment: countposts;float: left;z-index: 2;position:relative;font-size: 20px;font-weight: bold;color: #fff;background: #69B7E2; margin: 15px 5px 0px -6px; padding: 0px 10px; border-radius: 100%;}
li.recent-post-title { padding: 5px 0px;}
.recent-post-title { font-family: "Avant Garde",Avantgarde,"Century Gothic",CenturyGothic,AppleGothic,sans-serif;}
.recent-post-title a {color: #444;font-size: 13px; text-decoration: none; padding: 2px; font-weight: bold;}
.post-date {padding: 5px 2px 5px 30px; font-size: 11px; color: #999; margin-bottom: 5px;}
.recent-post-summ { border-left: 1px solid #69B7E2; color: #777; padding: 0px 5px 0px 20px; margin-left: 11px; font-family: Garamond,Baskerville,"Baskerville Old Face","Hoefler Text","Times New Roman",serif; font-size: 15px;}
</style></div>

Style #3

<script style="text/javascript" src="http://helplogger.googlecode.com/svn/trunk/helplogger/recentpoststhumbs.js"></script>
<script style="text/javascript">
var posts_no = 5;
var showpoststhumbs = true;
var readmorelink = true;
var showcommentslink = true;
var posts_date = true;
var post_summary = true;
var summary_chars = 70;</script>
<script src="/feeds/posts/default?orderby=published&alt=json-in-script&callback=showlatestpostswiththumbs"></script>
<a style="font-size: 9px; color: #CECECE; float: right; margin: 5px;" href="http://softwareduck.blogspot.com/2015/05/5-cool-recent-post-widgets-for-blogger.html" rel="nofollow">Recent Posts Widget</a>
<noscript>Your browser does not support JavaScript!</noscript>
<link href=http://fonts.googleapis.com/css?family=Oswald rel=stylesheet type=text/css/>
<style type="text/css">
img.recent-post-thumb {padding:2px;width:65px;height:65px;float:left;margin: 0px 10px 10px; background: #fff; border: 1px solid #69B7E2;}
.recent-posts-container {font-family: Oswald, sans-serif;  float: left;width: 100%;min-height: 70px;margin: 5px 0px 5px 0px;padding: 0;font-size:12px;}
ul.recent-posts-container li {padding:5px 0px;min-height:65px; list-style-type: none; margin-bottom: 5px;}
ul.recent-posts-container {counter-reset: countposts;list-style-type: none;}
ul.recent-posts-container li:before {content: counter(countposts,decimal);counter-increment: countposts;z-index: 2;position:absolute; left: 15px; font-size: 13px;font-weight: bold;color: #fff;background: #69B7E2;padding: 4px 10px; border-radius: 100%;}
.recent-posts-container a { text-decoration:none; }
.recent-post-title a {font-size: 13px; text-transform: uppercase; color: #2aace3;}
.recent-posts-details {margin: 5px 0px 0px 92px; }
.recent-posts-details a{ color: #777;}
</style>

Style #4

<script style="text/javascript" src="http://helplogger.googlecode.com/svn/trunk/helplogger/recentposts2.js"></script>
<script style="text/javascript">
var posts_no = 5;
var showpoststhumbs = false;
var readmorelink = true;
var showcommentslink = true;
var posts_date = true;
</script>
<script src="/feeds/posts/default?orderby=published&alt=json-in-script&callback=showlatestpostswiththumbs"></script>
<a style="font-size: 9px; color: #CECECE; float: right; margin: 5px;" href="http://softwareduck.blogspot.com/2015/05/5-cool-recent-post-widgets-for-blogger.html">Recent Posts Widget</a>
<noscript>Your browser does not support JavaScript!</noscript>
<link href=http://fonts.googleapis.com/css?family=Oswald rel=stylesheet type=text/css/>
<style type="text/css">
img.recent-post-thumb {padding: 2px; width:35px;height:35px;float:right;margin: -14px 0px 0px 5px; border: 1px solid #cea5ac; border-radius: 10%;}
.recent-posts-container {font-family: Oswald, sans-serif;  float: left;width: 100%;min-height: 70px;margin: 5px 0px 5px 0px;padding: 0;font-size:12px;}
ul.recent-posts-container li {padding:5px 0px;min-height:65px; list-style-type: none; margin: 0px 10px 5px 35px;}
ul.recent-posts-container {counter-reset: countposts;list-style-type: none;}
ul.recent-posts-container li:before {content: counter(countposts,decimal);counter-increment: countposts;z-index: 2;position:absolute; left: 5px; font-size: 16px;color: #4D4D4D;background: #F7F7F7;padding: 9px 14px; border: 1px solid #efefef;}
.recent-posts-container a { text-decoration:none; }
.recent-posts-container a:hover{color: #4DACE3;}
.post-date {color:#e0c0c6; font-size: 11px; }
.recent-post-title a {font-size: 13px; text-transform: uppercase; color: #5C4D4D;}
.recent-post-title { margin: 5px 0px; }
.recent-posts-details {border-top: 4px solid #AC707A; margin-top: 5px; padding-top: 5px;}
.recent-posts-details a{ color: #888;}
a.readmorelink {color: #4DACE3;}
</style>

Style #5

<script style="text/javascript" src="https://helplogger.googlecode.com/svn/trunk/helplogger/recentposts2.js"></script>
<script style="text/javascript">
var posts_no = 5;
var showpoststhumbs = true;
var readmorelink = true;
var showcommentslink = true;
var posts_date = true;
</script>
<script src="/feeds/posts/default?orderby=published&alt=json-in-script&callback=showlatestpostswiththumbs" rel="nofollow"></script>
<a style="font-size: 9px; color: #CECECE; float: right; margin: 5px;" href="http://softwareduck.blogspot.com/2015/05/5-cool-recent-post-widgets-for-blogger.html" rel="nofollow">Recent Posts Widget</a>
<noscript>Your browser does not support JavaScript!</noscript>
<link href=http://fonts.googleapis.com/css?family=Lobster|Gloria+Hallelujah rel=stylesheet type=text/css />
<style type="text/css">
img.recent-post-thumb {width:50px;height:50px;float:right;margin: -4px -35px 0px 0px; border: 4px solid #FCD6CB; border-radius: 100%;}
.recent-posts-container {font-family: Gloria Hallelujah, cursive;  float: left;width: 100%;min-height: 55px;margin: 5px 0px 5px 0px;padding: 0;font-size:12px;}
ul.recent-posts-container {counter-reset: countposts;list-style-type: none; background: #fff; }
ul.recent-posts-container li:before {content: counter(countposts,decimal);counter-increment: countposts;z-index: 2;position:absolute; left: -20px; font-size: 16px;color: #616662;background: #FCD6CB;padding: 9px 14px; border-radius: 100%; margin-top: 15px;}
ul.recent-posts-container li {padding:5px 0px;min-height:50px; list-style-type: none; margin: -2px 5px 5px 5px;  border-top: 2px solid #FCD6CB;}
ul.recent-posts-container {border: 2px solid #FCD6CB; }
.recent-posts-container a { text-decoration:none; }
.recent-posts-container a:hover { color: #222;}
.post-date {color:#e0c0c6; font-size: 11px; }
.recent-post-title a {font-size: 14px;color: #616662;}
.recent-post-title {padding: 6px 0px;}
.recent-posts-details a{ color: #888;}
.recent-posts-details {padding-bottom: 5px;}
a.readmorelink {color: #4DACE3;}
</style>

How to Add Recent Posts Widget on Blogger

Want to add one of the styles above? Just follow the following steps below:

Step 1. Log in to your Blogger dashboard and click on your blog
Step 2. Go to "Layout" and click the "Add a gadget" link on the right side
Step 3. From the pop-up window, scroll down and select the "HTML/JavaScript" gadget:

Step 4. Paste the code of the chosen widget found below it.
Step 5. Hit the "Save" button... and thats it!

Keep Your Blog Updated

Using a recent post widget for Blogger can truly benefit you and improve your skill as a blogger. As you can see, these designs can look great on Blogger sites, but they do act a little bit like a progress report for the author. If you start to fall behind, the dates on your recent post widget will definitely give you away.

Set a schedule and make sure that you are making regular posts on the blog. These posts will be automatically updated on your widget and readers can view this information whenever they want. Add your recent post widget for Blogger on the every page of the blog or in your template so that these posts can encourage others to continue reading, thus increasing the total time spent on your site. 

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