How do you print the first 5 records in an array?

[Bob Sanders]

Let's say I have an array defined as:

@people = ["Jim", "Jen", "Jess", "Jay", "Jack", "John", "Jeff", "Jed",
"Jill"]

How would I then print out the first 5 records of that array? (i.e. from
Jim to Jack)

Any ideas?

 

[Stefano Crocco]

Alle sabato 18 agosto 2007, Bob Sanders ha scritto:

Let's say I have an array defined as:

@people = ["Jim", "Jen", "Jess", "Jay", "Jack", "John", "Jeff", "Jed",
"Jill"]

How would I then print out the first 5 records of that array? (i.e. from
Jim to Jack)

Any ideas?

puts @people [0..4]

Stefano

 

[Bob Sanders]

Alle sabato 18 agosto 2007, Bob Sanders ha scritto:

Let's say I have an array defined as:

@people = ["Jim", "Jen", "Jess", "Jay", "Jack", "John", "Jeff", "Jed",
"Jill"]

How would I then print out the first 5 records of that array? (i.e. from
Jim to Jack)

Any ideas?

puts @people [0..4]

Stefano

Stefano, you're the best. Thank you!

 

[Dirk Bruijn]

Alle sabato 18 agosto 2007, Bob Sanders ha scritto:

Let's say I have an array defined as:

@people = ["Jim", "Jen", "Jess", "Jay", "Jack", "John", "Jeff", "Jed",
"Jill"]

How would I then print out the first 5 records of that array? (i.e. from
Jim to Jack)

Any ideas?

puts @people [0..4]

Stefano

0.upto(4) { |x| puts @people[x]}

 

[Sebastian Hungerecker]

Stefano Crocco wrote:

puts @people [0..4]

0.upto(4) { |x| puts @people[x]}

Why do you feel that that's preferable to Stefano's solution?

 

[Xavier Noria]

@people = ["Jim", "Jen", "Jess", "Jay", "Jack", "John", "Jeff", "Jed",
"Jill"]

How would I then print out the first 5 records of that array? (i.e.
from
Jim to Jack)

You can explicitly say "Take n items starting from index i" with the
syntax

array[i, n]

In your example that'd give

puts @people[0, 5]

-- fxn

 

[Bob Sanders]

You all are so helpful. This is why the ruby community rocks. Thank you
so much

 

[Stefan Rusterholz]

Let's say I have an array defined as:

@people = ["Jim", "Jen", "Jess", "Jay", "Jack", "John", "Jeff", "Jed",
"Jill"]

How would I then print out the first 5 records of that array? (i.e. from
Jim to Jack)

Any ideas?

puts(*@people.first(5))
Ruby, so surprisingly unsurprising

Regards
Stefan

 

[Konrad Meyer]

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Let's say I have an array defined as:
=20
@people =3D ["Jim", "Jen", "Jess", "Jay", "Jack", "John", "Jeff", "Jed",
"Jill"]
=20
How would I then print out the first 5 records of that array? (i.e. from
Jim to Jack)
=20
Any ideas?

One idea comes to mind:

@people.inject([]){|a,p|a<<p if a.length<5;a}.each{|p|puts p}

Anyone wanna throw in callcc too?
Cheers,
=2D-=20
Konrad Meyer <[email protected]> http://konrad.sobertillnoon.com/

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[Konrad Meyer]

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Let's say I have an array defined as:
=20
@people =3D ["Jim", "Jen", "Jess", "Jay", "Jack", "John", "Jeff", "Jed",
"Jill"]
=20
How would I then print out the first 5 records of that array? (i.e. from
Jim to Jack)
=20
Any ideas?

=20
One idea comes to mind:
=20
@people.inject([]){|a,p|a<<p if a.length<5;a}.each{|p|puts p}

Actually:

$><<@people.inject([]){|a,p|a<<p if a.length<5;a}*"\n"

=2D-=20
Konrad Meyer <[email protected]> http://konrad.sobertillnoon.com/

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[Dirk Bruijn]

Stefano Crocco wrote:

puts @people [0..4]

0.upto(4) { |x| puts @people[x]}

Why do you feel that that's preferable to Stefano's solution?

It's not. I mistakenly placed my reaction on the wrong leaf.

 

[David A. Black]

Hi --

Let's say I have an array defined as:

@people = ["Jim", "Jen", "Jess", "Jay", "Jack", "John", "Jeff", "Jed",
"Jill"]

How would I then print out the first 5 records of that array? (i.e. from
Jim to Jack)

Any ideas?

puts(*@people.first(5))
Ruby, so surprisingly unsurprising

I don't think you need the * there.


David

--
* Books:
RAILS ROUTING (new! http://www.awprofessional.com/title/0321509242)
RUBY FOR RAILS (http://www.manning.com/black)
* Ruby/Rails training
& consulting: Ruby Power and Light, LLC (http://www.rubypal.com)

 

[David A. Black]

Hi --

Stefano Crocco wrote:


puts @people [0..4]

0.upto(4) { |x| puts @people[x]}

Why do you feel that that's preferable to Stefano's solution?

It's not. I mistakenly placed my reaction on the wrong leaf.

I'd avoid iterating through a whole array just to puts its elements,
but in this case your code avoids creating a temporary sub-array. So
there might be some reason to use that technique.


David

--
* Books:
RAILS ROUTING (new! http://www.awprofessional.com/title/0321509242)
RUBY FOR RAILS (http://www.manning.com/black)
* Ruby/Rails training
& consulting: Ruby Power and Light, LLC (http://www.rubypal.com)

 

[Stefan Rusterholz]

Hi --



I don't think you need the * there.


David

Darn, and just when you say it is unsurprising you hit a surprising
thing.
Right, I keep forgetting that puts treats Arrays differently than every
other object.
Thanks for pointing out

Regards
Stefan

 

[Robert Klemme]

Let's say I have an array defined as:

@people = ["Jim", "Jen", "Jess", "Jay", "Jack", "John", "Jeff", "Jed",
"Jill"]

How would I then print out the first 5 records of that array? (i.e. from
Jim to Jack)

Any ideas?

One idea comes to mind:

@people.inject([]){|a,p|a<<p if a.length<5;a}.each{|p|puts p}

Actually:

$><<@people.inject([]){|a,p|a<<p if a.length<5;a}*"\n"

Although I'm always fond of solutions using #inject in this case I'm
sorry to say that but this is not only inefficient but totally
obfuscated. If you feel you have to iterate then you can immediately
print members. These are my preferred solutions

# fast and readable
5.times {|i| puts @people}
0.upto(4) {|i| puts @people}

# might be less efficient but
# very readable
puts @people[0,5]
puts @people[0...5]
puts @people[0..4]

Note: it's not too unlikely that those variants with the sub arrays are
actually faster, because that is all done in C code.

Cheers

robert

 

[Phlip]

0.upto(4) { |x| puts @people[x]}

5.times{ puts @people.shift }

Hey - they didn't say non-destructively!

 

[Bob Gustafson]

0.upto(4) { |x| puts @people[x]}

5.times{ puts @people.shift }

Hey - they didn't say non-destructively!

--
Phlip
http://www.oreilly.com/catalog/9780596510657/
"Test Driven Ajax (on Rails)"
assert_xpath, assert_javascript, & assert_ajax

puts @people[0..4].join("\n")

 

[James Edward Gray II]

Let's say I have an array defined as:

@people = ["Jim", "Jen", "Jess", "Jay", "Jack", "John", "Jeff", "Jed",
"Jill"]

I see you got your answer, but I wanted to add that you can do the
above with a lot less noise:

@people = %w[Jim Jen Jess Jay Jack John Jeff Jed Jill]

James Edward Gray II

 

[rio4ruby]

One idea comes to mind:

@people.inject([]){|a,p|a<<p if a.length<5;a}.each{|p|puts p}

Anyone wanna throw in callcc too?

You could use Rio for this problem:

require 'rio'
rio(?-) < @people[0...5].join($/) + $/

 

[David A. Black]

Hi --

puts @people[0..4].join("\n")

Assuming people don't end with "\n", that will have the same effect as
doing it without the join:

irb(main):007:0> people = %w{ me you him her them }
=> ["me", "you", "him", "her", "them"]
irb(main):008:0> puts people[0..4].join("\n")
me
you
him
her
them
=> nil
irb(main):009:0> puts people[0..4]
me
you
him
her
them
=> nil

If they do end with "\n", then they'll be separated by blank lines if
you do the join.


David

--
* Books:
RAILS ROUTING (new! http://www.awprofessional.com/title/0321509242)
RUBY FOR RAILS (http://www.manning.com/black)
* Ruby/Rails training
& consulting: Ruby Power and Light, LLC (http://www.rubypal.com)