I am new to streamlit, and I am trying to display a pydeck layer with columns. I want the column height to be the rain (mm) column I am providing in a dataframe, but whenever I use get_evelation="rain (mm)", I get the following error:
Error: Function calls not allowed in JSON expressions
at http://localhost:8501/static/js/7.f6560317.chunk.js:2:512302
at u (http://localhost:8501/static/js/7.f6560317.chunk.js:2:512666)
at http://localhost:8501/static/js/7.f6560317.chunk.js:2:512596
at Array.forEach (<anonymous>)
at u (http://localhost:8501/static/js/7.f6560317.chunk.js:2:512568)
at u (http://localhost:8501/static/js/7.f6560317.chunk.js:2:512673)
at t.default (http://localhost:8501/static/js/7.f6560317.chunk.js:2:512250)
at e.h [as convertFunction] (http://localhost:8501/static/js/7.f6560317.chunk.js:2:1049691)
at http://localhost:8501/static/js/7.f6560317.chunk.js:2:2778265
at y (http://localhost:8501/static/js/7.f6560317.chunk.js:2:2778495)
The function I am using to render my map is the following:
def make_map2(data, lat, lon, zoom):
column_layer = pdk.Layer(
"ColumnLayer",
data=data,
get_position=["lon", "lat"],
get_elevation="rain (mm)",
elevation_scale=20,
radius=2000,
get_fill_color=[180, 0, 200, 140],
pickable=True,
auto_highlight=True,
extruded=True
)
tooltip={'html': 'Location: {location}</br> Date: {date} </br> Rainfall (mm): {rain_mm}</br> Type: {type}'}
r = pdk.Deck(column_layer,
initial_view_state={
"latitude": lat,
"longitude": lon,
"zoom": zoom,
"pitch": 60
},
tooltip=tooltip,
map_provider="mapbox",
map_style='mapbox://styles/mapbox/light-v9',
)
map2 = st.write(r)
return map2
The input data have this structure:
date location lat lon rain (mm) type
0 2021-09-15 lowestoft 52.483 1.727 54.115513 predicted
1 2021-09-15 heathrow 51.479 -0.449 30.008739 predicted
2 2021-09-15 eastbourne 50.762 0.285 90.584396 predicted
3 2021-09-15 cambridge 52.245 0.102 51.445862 predicted
4 2021-09-15 manston 51.346 1.337 81.089737 predicted
5 2021-09-15 oxford 51.761 -1.262 39.420902 predicted
This could be as simple as a misspelled argument:
get_evelation="rain (mm)" should be get_elevation="rain (mm)"
Edit: Irrespective of the misspelled argument name, this error occurs in how pydeck parses string literals. pydeck assumes that rain (mm) is a function call, and throws an error. Naming the get_elevation column without the spaces or parenthesis allows the example to work:
import pandas as pd
import numpy as np
import streamlit as st
import pydeck as pdk
df = pd.read_csv("~/Desktop/data.csv")
#to prove hypothesis, make column name one continuous string with no extra characters
df["rain_noparens"] = df["rain (mm)"]
view = pdk.data_utils.compute_view(df[["lon", "lat"]])
view.pitch = 75
view.bearing = 60
column_layer = pdk.Layer(
"ColumnLayer",
data=df,
get_position=["lon", "lat"],
get_elevation="rain_noparens",
elevation_scale=20,
radius=2000,
get_fill_color=[180, 0, 200, 140],
pickable=True,
auto_highlight=True,
)
tooltip = {
"html": "Location: {location}</br> Date: {date} </br> Rainfall (mm): {rain (mm)}</br> Type: {type}"
}
r = pdk.Deck(
column_layer,
initial_view_state=view,
tooltip=tooltip,
map_provider="mapbox",
map_style="mapbox://styles/mapbox/light-v9",
)
st.pydeck_chart(r)
See also: https://github.com/streamlit/streamlit/issues/3992