tw_leaflet: Creates a leaflet map
In gvegayon/twitterreport: Out-of-the-Box Analysis and Reporting Tools for Twitter

Description Usage Arguments Details Value Author(s) Examples

This function works as a wrapper of the leaflet function, creating a map with circles which sizes are set by the number of observations in those coordinates.

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tw_leaflet(dat, coordinates = NULL, popup = NULL, lat = NULL,
  lng = NULL, radii = ~sqrt(n) * 5000, weight = 1,
  cluster.method = "centroid", nclusters = min(c(50, nrow(dat)%/%3)), ...)

`dat`	A twitter dataset (with coordinates)
`coordinates`	Name of the `coordinates` variable (see details)
`popup`	Name of the grouping variable (for example, `screen_name`)
`lat`	Name of the latitude variable
`lng`	Name of the longitude variable
`radii`	Formula to compute the radious of the circles
`weight`	Thickness of the circles' borders
`cluster.method`	Clustering method (see `hclust()`)
`nclusters`	Max number of clusters to include
`...`	Further arguments to be passed to `addCircles()`

The coordinates must be in the format of longitude:latitude (as the twitter API returns).

In order to improve visualization, the function performs Hierarchical Clustering via hclust() (from the stats package), grouping observations by geo coordinates. For each cluster, the final lat/lng coords are defined as the mean within the cluster.

In the case of radii, it is measured in meters (in the map). The n is the number of observations in that cluster.

For performance considerations, it is recommended not to use more than 1,000 observations (Try using a random sample from your data!) as hclust requires computing square matrices.

A map object (see the leaflet() package)

George G. Vega Yon

## Not run: 
# Getting the data
data(senate_tweets)

# using formulas to pass the variables names
tw_leaflet(senate_tweets,~coordinates,~screen_name)
tw_leaflet(senate_tweets,~coordinates)

# Using characters to pass the variables names
tw_leaflet(senate_tweets,'coordinates','screen_name')
tw_leaflet(senate_tweets,'coordinates')

# Aggregating until get only 3 big groups
tw_leaflet(senate_tweets,'coordinates', nclusters=3)

## End(Not run)