### Fabric calculator - a better way to do it?

by ailie (Friar)
 on Dec 06, 2001 at 04:04 UTC Need Help??
ailie has asked for the wisdom of the Perl Monks concerning the following question:

This is a script I wrote to calculate how much fabric I need when making various quilt blocks. At the moment it's run from the command line, but I'd like to eventually get it so it can be run from a web page. That's where I really started to get frustrated. Alternately, a GUI might be sort of neat.

Anyway, I would be interested in receiving feedback on the script as it stands now. I have a vague feeling that perhaps there are better, cleaner ways to do much of what I've got, and I'd like to learn them.

```#!/usr/bin/perl -w
use strict;

# How many fabrics are you using?

my \$j;
my \$number_of_fabrics;
print "How many fabrics are you using? \n";
chomp(\$number_of_fabrics = <STDIN>);
for (\$j = 1; \$j <= \$number_of_fabrics; \$j++) {

# How wide is the fabric you are using?

my %fabric_width;
my \$fab_width;
print "How wide is fabric \$j? \n";
chomp(\$fab_width = <STDIN>);
\$fabric_width{\$j} = \$fab_width - 2;
print "To be safe, we'll use a width of \$fabric_width{\$j} for fabri
+c \$j. \n";

# How many different shapes is a block made of?

my \$number_of_shapes;
print "How many different shapes of fabric \$j is a block made of? \
+n";
chomp(\$number_of_shapes = <STDIN>);

# What are the dimensions of the shapes?

my \$i;
my %width;
my %height;
my %shape;
my \$piece;
for (\$i = 1; \$i <= \$number_of_shapes; \$i++) {
my \$shape_width;
print "What is the width of shape \$i? \n";
chomp(\$shape_width = <STDIN>);
\$width{\$i} = \$shape_width;
my \$shape_height;
print "What is the height of shape \$i? \n";
chomp(\$shape_height = <STDIN>);
\$height{\$i} = \$shape_height;
\$shape{\$i} = \$shape_width . "x" . \$shape_height;
}
print "Shape dimensions: \n";
foreach \$i (keys (%shape)) {
print "The dimensions of shape \$i are \$shape{\$i}\n";
}

# For each shape, how many can be made per yard of fabric?

my \$number_per_fabric_width_strip;
my \$strips_per_yard;
my \$number_per_yard;
my \$number_of_pieces;
my %pieces;
my \$number_of_strips;
my \$strip_yardage;
my \$remainder;
my \$fabric_yardage;
my \$number_of_blocks;
my \$total_pieces;
foreach \$i (keys (%height)) {
\$number_per_fabric_width_strip = \$fabric_width{\$j} / (\$height{\$i
+});
\$number_per_fabric_width_strip = int \$number_per_fabric_width_st
+rip;
print "You can get \$number_per_fabric_width_strip piece(s) of sh
+ape \$i per
\$width{\$i}\" strip of fabric \$j.\n";
\$strips_per_yard = 36 / (\$width{\$i});
\$strips_per_yard = int \$strips_per_yard;
print "You can get \$strips_per_yard \$width{\$i}\" strips per yard
+. \n";
\$number_per_yard = \$number_per_fabric_width_strip * \$strips_per_
+yard;
print "You can get \$number_per_yard of shape \$i per yard of
\$fabric_width{\$j}\" of fabric \$j. \n";
print "How many of shape \$i do you need per block? \n";
chomp(\$number_of_pieces = <STDIN>);
\$pieces{\$i} = "\$number_of_pieces";
print "You need \$number_of_pieces per block. \n";
print "How many blocks are you making? \n";
chomp(\$number_of_blocks = <STDIN>);
print "You are making \$number_of_blocks blocks. \n";
\$total_pieces = \$number_of_pieces * \$number_of_blocks;
print "You need \$total_pieces of shape \$i. \n";
if (\$total_pieces <= \$number_per_fabric_width_strip) {
print "You will need one \$width{\$i}\" strip of fabric \$j. \n"
+;
}
else {
\$number_of_strips = \$total_pieces / \$number_per_fabric_width_
+strip;
\$number_of_strips = int \$number_of_strips;
\$remainder = \$total_pieces % \$number_per_fabric_width_strip;
\$strip_yardage= \$number_of_strips * \$width{\$i};
if (\$remainder == 0) {
print "You will need exactly \$strip_yardage\". \n";
}
else {
\$fabric_yardage = \$strip_yardage + \$width{\$i};
print "You will need \$fabric_yardage\" of fabric \$j. The last
+\$width{\$i}\" strip will have only \$remainder pieces cut from it. \n";
}
}
}
}

Replies are listed 'Best First'.
Re: Fabric calculator - a better way to do it?
by jynx (Priest) on Dec 06, 2001 at 09:36 UTC

A few suggestions,

Most of these are rather cosmetic, but they should help readability.

Considering how many times you read from STDIN you may want to farm that part out to a subroutine. It would remove clutter from the rest of the code and should be a bit more maintainable later.

For structures like %width an array seems to make more sense than a hash. It works either way, but it's probably a good idea to try and use more appropriate tools when possible.

Also you can reduce the number of variables you have to keep track of by using a hash for multiple things. For example, your \$number_of_* variables in the last section could probably be written as (using a subroutine for getting STDIN):

```my %number;
\$number{blocks} = get_input("How many blocks are you making?");
\$number{strips} = int( \$total_pieces / \$number_per_fabric_width_strip)
+;
etc...
jynx
(crazyinsomniac:) Re: Fabric calculator - a better way to do it?
by crazyinsomniac (Prior) on Dec 06, 2001 at 11:42 UTC
This is me just being a monkey and testing the script out:
```F:\dev>perl fabric.pl
How many fabrics are you using?
2
How wide is fabric 1?
1
To be safe, we'll use a width of -1 for fabric 1.
How many different shapes of fabric 1 is a block made of?
1
What is the width of shape 1?
1
What is the height of shape 1?
2
Shape dimensions:
The dimensions of shape 1 are 1x2
You can get 0 piece(s) of shape 1 per
1" strip of fabric 1.
You can get 36 1" strips per yard.
You can get 0 of shape 1 per yard of
-1" of fabric 1.
How many of shape 1 do you need per block?
23
You need 23 per block.
How many blocks are you making?
2
You are making 2 blocks.
You need 46 of shape 1.
Illegal division by zero at fabric.pl line 88, <STDIN> line 7.

F:\dev>
I'll update this node after I've messed with the code.

My monkeying around immediately proves insightful into how you can improve this (at least it appears so to me).

A good strategy might be to turn this into a module, and then, write "interfaces" for it, like commandline, CGI, GUI. All I have to say at this point is, not bad quiltmaker (some of your math may be funny, but useful to real people and immensly perlmonkish -- no prog/perl bg, good practices at the beginning). I see sanity checks, units of measurement conversions, price estimation.... ;D

update:

```#!/usr/bin/perl -w
use strict;

# How many fabrics are you using?

my \$number_of_fabrics;

print "How many fabrics are you using? \n";

chomp(\$number_of_fabrics = <STDIN>);

\$number_of_fabrics =~ s/\D//; # only allow number input

## \$number_of_fabrics ||= 3;  # assume default quietly

unless(\$number_of_fabrics and \$number_of_fabrics >=3 )
{
warn "Ahem!!! You must enter a NUMBER >= 3, but that's ok, default
+ is 3";
\$number_of_fabrics = 3;
}
#... more to come ... ;D

___crazyinsomniac_______________________________________
Disclaimer: Don't blame. It came from inside the void

perl -e "\$q=\$_;map({chr unpack qq;H*;,\$_}split(q;;,q*H*));print;\$q/\$q;"

Wow. It never even occurred to me to put in widths like that, since quilting fabric is almost always 45" wide, sometimes 60" wide - certainly not 1" wide. Of course, now I'm going "D'oh!"

The math is inelegant, but that's a basic fact of calculating fabric yardages for quilts. Simple math, but annoying.

I like the module idea. Of course, I have no idea how to go about such a thing, but learning is really the whole point.

Price estimation is simple:
print "No, you may not buy more fabric. \n";

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