Halving length of a crochet pattern

[Nicolapen]

I found a pattern I want to try but only want my finished product to be half as long as the original, same width. Design is a rectangle

Can I just buy half the amount of yarn pattern requests (miss out a few of the colours) or is it more complicated than that

Main stitch used in pattern is hdc 

Yarn required is Rainbow Cotton 8/8. Colour 1: 110g. Colours 2-10: 40g 

Edited January 18, 2021 by Nicjane

[Granny Square]

I don't see why not.  

I see each skein is 50 grams.  Halving the # of not-main colors should be safe as the full 40g called for would have been covered by1 skein; if it were me I'd still buy 2 skeins of the main color to be safe, because half of 110g=55g, a bit more than 1 skein.  I always buy 1 skein more than the pattern calls for, and once in a while I end up having to use a bit of that skein.