TITLE: Notation for the all-ones vector
QUESTION [27 upvotes]: What's the most common way of writing the all-ones vector, that is, the vector, when projected onto each standard basis vector of a given vector space, having length one? The zero vector is frequently written $\vec{0}$, so I'm partial to writing the all-ones vector as $\vec{1}$, but I don't know how popular this is, and I don't know if a reader might confuse it with the identity matrix.
I'm writing for a graph theory audience, if that helps pick a notation.

REPLY [5 votes]: Let $I \subset \{ 1,2,3,\ldots, n \} $. Let $e_I = \sum_{i\in I} e_i.$ Let $[n]=\{ 1,2,3, \ldots, n \} $. 
Then $\vec{1}=e_{[n]}$. Also $e_{\{i\}} = e_i$.
This is not satisfactory to your context, but may have the advantage of alternative usages in subsequent contexts.