In the marks section in vega, the from pragma points to the dataset that should be used: for every datapoint in the dataset, a single mark is created. If no from is provided, vega defaults to creating a single mark. Let’s for example add a red square and a bit of text to the plot above:
{
"$schema": "https://vega.github.io/schema/vega/v5.json",
"width": 400,
"height": 200,
"padding": 5,
"data": [
{
"name": "table",
"values": [
{"x": 15, "y": 8},
{"x": 72, "y": 25},
{"x": 35, "y": 44},
{"x": 44, "y": 29}
]
}
],
"scales": [
{
"name": "xscale",
"domain": {"data": "table", "field": "x"},
"range": "width"
},
{
"name": "yscale",
"domain": {"data": "table", "field": "y"},
"range": "height"
}
],
"marks": [
{
"type": "symbol",
"from": {"data":"table"},
"encode": {
"enter": {
"x": {"scale": "xscale", "field": "x"},
"y": {"scale": "yscale", "field": "y"}
}
}
},
{
"type": "rect",
"encode": {
"enter": {
"x": {"value": 50},
"y": {"value": 50},
"width": {"value": 30},
"height": {"value": 30},
"fill": {"value": "red"}
}
}
},
{
"type": "text",
"encode": {
"enter": {
"text": {"value": "This is some text"},
"x": {"value": 100},
"y": {"value": 50}
}
}
}
]
}
Notice that there is no from defined for the square and the text.