xlsxwriter: modifying parts of a line in a scatter chart - xlsxwriter

Question

in the Python package xlsxwriter, is it possible to format a part of a scatter chart series differently than another part? for example, a scatter chart where some sections of the line of a specific series are blue, and other sections of the same line are red. it is certainly possible in Excel itself by modifying specific data points.
I tried using the 'points' option in many combinations without success. I don't know which options are valid for it in a scatter chart.
UPDATE:
here is an example of what I'm trying to achieve. This was created directly in Excel, not through xlsxwriter. Notice how one section of the line is dashed and red, and another is a different thickness. To create it, simply select a data point and use the options in the sidebar to adjust formatting.

Answer 1

I've made an example that I think answers your question.
I'm using Python 3.5 and xlsxwriter 0.9.6.
In chart 1, I changed the color of the markers based on whether they were in a particular group. It's fairly straightforward if chart 1 is what you're looking for.
In chart 2, I show how to hard code a continuous line with different colors (there may be a better way to do this).
import xlsxwriter
import numpy as np
import pandas as pd
dates = pd.DataFrame({'excel_date':pd.date_range('1/1/2016', periods=12, freq='M')})
dates.excel_date = dates.excel_date - pd.datetime(1899, 12, 31)
data = np.array([11,20,25,35,40,48,44,31,25,38,49,60])
selection = np.array([4,5,6,8,11])
#Creating a list - you could hard code these lines if you prefer depending on the size of your series
diff_color_list = list()
for n in range(1, 13):
if n in selection:
diff_color_list.append({'fill':{'color': 'blue', 'width': 3.25}},)
else:
diff_color_list.append({'fill':{'color': 'red', 'width': 3.25}},)
#Workbook Creation
workbook = xlsxwriter.Workbook("test.xlsx")
format = workbook.add_format({'num_format':'mmm-yy'})
worksheet1 = workbook.add_worksheet("testsheet")
worksheet1.write('A1', 'Date')
worksheet1.write('B1', 'Data')
worksheet1.write_column('A2', dates.excel_date, format)
worksheet1.write_column('B2', data)
chart1 = workbook.add_chart({'type': 'scatter'})
# Configure the series.
chart1.add_series({'categories': '=testsheet!$A$2:$A$13',
'values': '=testsheet!$B$2:$B$13',
'points': diff_color_list
})
chart1.set_title ({'name': 'Results'})
chart1.set_x_axis({'name': 'Date'})
chart1.set_y_axis({'name': 'Data'})
chart1.set_legend({'none': True})
# Second chart with alternating line colors
chart2 = workbook.add_chart({'type': 'scatter',
'subtype': 'straight'})
chart2.add_series({'categories': '=testsheet!$A$2:$A$3',
'values': '=testsheet!$B$2:$B$3',
'line':{'color': 'blue'}
})
chart2.add_series({'categories': '=testsheet!$A$3:$A$4',
'values': '=testsheet!$B$3:$B$4',
'line':{'color': 'red'}
})
chart2.add_series({'categories': '=testsheet!$A$4:$A$5',
'values': '=testsheet!$B$4:$B$5',
'line':{'color': 'blue'}
})
chart2.set_title ({'name': 'Results'})
chart2.set_x_axis({'name': 'Date'})
chart2.set_y_axis({'name': 'Data'})
chart2.set_legend({'none': True})
worksheet1.insert_chart('D6', chart1)
worksheet1.insert_chart('L6', chart2)
workbook.close()

Answer 2

The question is a little bit confusing since you talk about changing the color of parts of a line but also about points.
I'm going to assume you are referring to changing the color of points/markers since as far as I know changing the color of line segments in a series isn't possible in Excel.
Anyway, it it possible to change marker colors in a scatter chart using XlsxWriter. For example:
import xlsxwriter
workbook = xlsxwriter.Workbook('chart_scatter.xlsx')
worksheet = workbook.add_worksheet()
# Add the worksheet data that the charts will refer to.
worksheet.write_column('A1', [1, 2, 3, 4, 5, 6])
worksheet.write_column('B1', [15, 40, 50, 20, 10, 50])
# Create a new scatter chart.
chart = workbook.add_chart({'type': 'scatter',
'subtype': 'straight_with_markers'})
# Configure the chart series. Increase the default marker size for clarity
# and configure the series points to
chart.add_series({
'categories': '=Sheet1!$A$1:$A$6',
'values': '=Sheet1!$B$1:$B$6',
'marker': {'type': 'square',
'size': 12},
'points': [
None,
None,
{'fill': {'color': 'green'},
'border': {'color': 'black'}},
None,
{'fill': {'color': 'red'},
'border': {'color': 'black'}},
],
})
# Turn off the legend for clarity.
chart.set_legend({'none': True})
# Insert the chart into the worksheet.
worksheet.insert_chart('D2', chart)
workbook.close()
Output: