were the nominees selected on the basis of the number of votes or were they selected as per their ambition?
Number of votes
Balloting
The results showed that the delegates had scattered their ballots to a variety of candidates, with no one close to the 492 necessary to nominate (at that time, Democratic conventions required a two-thirds majority for nomination). 
on what date did the 1880 democratic national convention occur? June 22 to 24, 1880 what was the purpose for this meeting? To nominate Winfield S. Hancock for president and William H. English for vice president in the US presidential election of 1880. in which venue was this held? Music Hall in Cincinnati, Ohio can you name some people who attended this? Henry B. Payne who is the above person? American politician can you name a few nominees from this convention? Justice Stephen J. Field, Thomas F. Bayard. Gray, to name a few.
On the basis of the number of votes UNANSWERABLE UNANSWERABLE
1880 Democratic National Convention
Introduction
Six men were officially candidates for nomination at the convention, and several more also received votes.
wiki:15512042
1880 Democratic National Convention [SEP] Balloting
The clerk called the roll of the states again, and a band played "Yankee Doodle" and "Dixie" as the ballots were tallied. The results showed that the delegates had scattered their ballots to a variety of candidates, with no one close to the 492 necessary to nominate (at that time, Democratic conventions required a two-thirds majority for nomination). There was a clear delineation, however, as Hancock and Bayard, with 171 and 158½ respectively, were far ahead of the pack. The next closest, Payne, had less than half of Hancock's number, with 81. After one minor shift of ½ ballot, the totals were announced to the delegates.