BME180 processing output for Dashboard

Now this is the flow I am using - can anyone tell me what I have done and why it works so that I can learn a bit more please.

[{"id":"5e695e6.063222","type":"function","z":"782be2e6.43ff0c","name":"BME280","func":"var temp = msg.payload.BME280.Temperature;\nmsg.payload = temp;\nreturn msg;\n","outputs":1,"noerr":0,"x":400,"y":80,"wires":[["9fd41922.15cb88"]]},{"id":"caf61448.ed977","type":"mqtt in","z":"782be2e6.43ff0c","name":"","topic":"house/weather/tele/SENSOR","qos":"0","datatype":"json","broker":"310445f6.902322","x":180,"y":80,"wires":[["5e695e6.063222"]]},{"id":"9fd41922.15cb88","type":"function","z":"782be2e6.43ff0c","name":"change topic to Temperature","func":"msg.topic = \"house/weather/tele/SENSOR/Temperature\"\nreturn msg;","outputs":1,"noerr":0,"x":620,"y":80,"wires":[["e33f9f81.020f68"]]},{"id":"e33f9f81.020f68","type":"ui_chart","z":"782be2e6.43ff0c","name":"","group":"b1e25851.00fed8","order":5,"width":0,"height":0,"label":"Outside Temp","chartType":"line","legend":"false","xformat":"dd HH:mm","interpolate":"linear","nodata":"","dot":false,"ymin":"","ymax":"","removeOlder":"2","removeOlderPoints":"","removeOlderUnit":"86400","cutout":0,"useOneColor":false,"colors":["#1f77b4","#aec7e8","#ff7f0e","#2ca02c","#98df8a","#d62728","#ff9896","#9467bd","#c5b0d5"],"useOldStyle":false,"outputs":1,"x":880,"y":80,"wires":[[]]},{"id":"310445f6.902322","type":"mqtt-broker","z":"","name":"","broker":"192.168.1.20","port":"1883","clientid":"","usetls":false,"compatmode":false,"keepalive":"60","cleansession":true,"birthTopic":"","birthQos":"0","birthPayload":"","closeTopic":"","closeQos":"0","closePayload":"","willTopic":"","willQos":"0","willPayload":""},{"id":"b1e25851.00fed8","type":"ui_group","z":"","name":"Weather","tab":"bea48e01.e35b98","disp":true,"width":"6","collapse":false},{"id":"bea48e01.e35b98","type":"ui_tab","z":"","name":"Tab","icon":"dashboard","order":0,"disabled":false,"hidden":false}]

Work backwards. You have a ui_chart node that needs to receive a number in msg.payload
and the name of the series the number goes with in msg.topic.

You could combine the two function nodes or eliminate them by using a change node.

What is odd is the number of escaped characters in your debug