python - 如何从 Pandas 数据框中输入 Plotly 条形图的 x 和 y 值
问题描述
我有以下玩具数据集:
df = pd.DataFrame({'Make':['Ford', 'Ford', 'Ford', 'BMW', 'BMW', 'BMW', Mercedes', 'Mercedes', 'Mercedes'],
'Score':['88.6', '76.6', '100', '79.1', '86.8', '96.4', '97.3', '98.7', '98.5'],
'Dimension':['Speed', 'MPG', 'Styling', 'Speed', 'MPG', 'Styling', 'Speed', 'MPG', 'Styling'],
'Month':['Apr-19', 'Apr-19', 'Apr-19', 'Apr-19', 'Apr-19', 'Apr-19', 'Apr-19', 'Apr-19', 'Apr-19']})
我正在使用Plotly
和Dash
框架来构建基于 Web 的交互式仪表板。代码如下:
import base64
import datetime
import io
import dash
from dash.dependencies import Input, Output, State
import dash_core_components as dcc
import dash_html_components as html
import plotly.graph_objects as go
import dash_table
import pandas as pd
app = dash.Dash()
app.layout = html.Div([
dcc.Upload(
id='upload-data',
children=html.Div([
'Drag and Drop or ',
html.A('Select Files')
]),
style={
'width': '100%',
'height': '60px',
'lineHeight': '60px',
'borderWidth': '1px',
'borderStyle': 'dashed',
'borderRadius': '5px',
'textAlign': 'center',
'margin': '10px'
},
# Allow multiple files to be uploaded
multiple=True
),
html.Div(id='output-data-upload'),
])
def parse_contents(contents, filename, date):
content_type, content_string = contents.split(',')
decoded = base64.b64decode(content_string)
try:
if 'csv' in filename:
# Assume that the user uploaded a CSV file
df = pd.read_csv(
io.StringIO(decoded.decode('utf-8')))
elif 'xls' in filename:
# Assume that the user uploaded an excel file
df = pd.read_excel(io.BytesIO(decoded))
except Exception as e:
print(e)
return html.Div([
'There was an error processing this file.'
])
return html.Div([
html.H5(filename),
html.H6(datetime.datetime.fromtimestamp(date)),
dash_table.DataTable(
data=df.to_dict('records'),
columns=[{'name': i, 'id': i} for i in df.columns]
),
html.Hr(), # horizontal line
#### How to get the x and y values DYNAMICALLY from the data frame to pass into the Bar() function? ####
dcc.Graph(
figure = go.Figure(data=[
go.Bar(name=df.columns.values[0], x=pd.unique(df['Make']), y=[88.6, 76.6, 100], text=[88.6, 76.6, 100], textposition='auto'),
go.Bar(name=df.columns.values[1], x=pd.unique(df['Make']), y=[92.5, 93.6, 93.4], text=[92.5, 93.6, 93.4], textposition='auto'),
go.Bar(name=df.columns.values[2], x=pd.unique(df['Make']), y=[99.1, 99.2, 95.9], text=[99.1, 99.2, 95.9], textposition='auto'),
])
),
html.Hr(),
# For debugging, display the raw contents provided by the web browser
html.Div('Raw Content'),
html.Pre(contents[0:200] + '...', style={
'whiteSpace': 'pre-wrap',
'wordBreak': 'break-all'
})
])
@app.callback(Output('output-data-upload', 'children'),
[Input('upload-data', 'contents')],
[State('upload-data', 'filename'),
State('upload-data', 'last_modified')])
def update_output(list_of_contents, list_of_names, list_of_dates):
if list_of_contents is not None:
children = [
parse_contents(c, n, d) for c, n, d in
zip(list_of_contents, list_of_names, list_of_dates)]
return children
if __name__ == '__main__':
app.run_server(debug=True)
总之,用户上传了一个 .csv 文件并Pandas data frame
创建了一个。然后根据数据框中的数据呈现条形图。
如您所见,该go.Bar()
函数具有来自数据框的x
值。值的数量可能会波动(在这种情况下,它是 3,但它可能是 2 或 10 或介于两者之间的任何位置)。我将值以非常不雅的方式硬编码为列名中的索引值。y
df
x
x
问题:
1) 动态读取值的最 Pythonic 方式是什么x
,以便代码接受可变数量的x
值?
2)从数据框中y
动态读取关联值的最佳方法是什么?df
(出于本示例的目的,我将它们完全硬编码)
提前致谢?
解决方案
你用这种方式尝试过吗?
dcc.Graph(
figure = go.Figure(data=[
go.Bar(name=df.columns.values[0], x=pd.unique(df['Make']), y=df['Score'], text=df['Score'], textposition='auto'),
go.Bar(name=df.columns.values[1], x=pd.unique(df['Make']), y=df['Score'], text=df['Score'], textposition='auto'),
go.Bar(name=df.columns.values[2], x=pd.unique(df['Make']), y=df['Score'], text=df['Score'], textposition='auto'),
])
),
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