Write shp into python and fill in the attribute table

Question

I am struggling to create a shp and I want it to writes records on the attribute table. I can create the shp but I can not fill in with the correct records. I import an Excel file, that contains the fields "code", "x_Start", "y_Start", "x_Finish", "y_Finish" and I want the field 'code' on the shp table.

Here is the code:

import pandas as pd
import geopandas as gpd
import requests
from shapely.geometry import Point


#import excel
import requests
df = pd.read_excel("NI.xls")
df.head()

#then I create trajectories through an API and I get a list. 

a = list(zip(*[list(df['x_S']), list(df['y_S']), list(df['x_F']), list(df['y_F'])]))
#print (a)
b = [bb for bb in [create_trajectory(coords) for coords in a] if not bb is None]
dg = pd.DataFrame(b)
dg

#I can create the shp from dg but I can't know how to fill in the attribute with th df. Ν.Β. that I do not get the same number routes as I give on excel file.

import shapefile

# Create a polyline shapefile writer
with shapefile.Writer("shapefiles/test/routeNI6") as w:
    #w = shapefile.Writer(shapefile.POLYLINE)

    # Add our fields
    w.field("NAME", "C", "40")


    #lines = []
    for i, row in df.iterrows():
        w.record(df.code)


        w.line([list(row.dropna())])

I want to add only the 'code' records. and here are the errors that I get

TypeError                                 Traceback (most recent call last)
<ipython-input-115-04aa2ea41a9f> in <module>
     21 
---> 22         w.line([list(row.dropna())])

~\Anaconda3\lib\site-packages\shapefile.py in line(self, lines)
   1670         shapeType = POLYLINE
-> 1671         self._shapeparts(parts=lines, shapeType=shapeType)
   1672 

~\Anaconda3\lib\site-packages\shapefile.py in _shapeparts(self, parts, shapeType)
   1756                 if not isinstance(point, list):
-> 1757                     point = list(point)
   1758                 polyShape.points.append(point)

TypeError: 'float' object is not iterable

During handling of the above exception, another exception occurred:

ShapefileException                        Traceback (most recent call last)
<ipython-input-115-04aa2ea41a9f> in <module>
     20         #lines.append(list(row))
     21 
---> 22         w.line([list(row.dropna())])

~\Anaconda3\lib\site-packages\shapefile.py in __exit__(self, exc_type, exc_val, exc_tb)
   1099         Exit phase of context manager, finish writing and close the files.
   1100         """
-> 1101         self.close()
   1102 
   1103     def __del__(self):

~\Anaconda3\lib\site-packages\shapefile.py in close(self)
   1120                 raise ShapefileException("When saving both the dbf and shp file, "
   1121                                          "the number of records (%s) must correspond "
-> 1122                                          "with the number of shapes (%s)" % (self.recNum, self.shpNum))
   1123         # Fill in the blank headers
   1124         if self.shp and shp_open:

ShapefileException: When saving both the dbf and shp file, the number of records (1) must correspond with the number of shapes (0)

I have added the libraries that I use. Actually, I have some couple of thousand polylines. This code is a part of the whole code.

I import the excel file as df and then I create trajectories as dg. So I want to create a shp with features from the dg and to fill in the attribute from df. I hope it helps. I am sorry for the inconvenience but I am quite fresh.

Answer 1

Your code has several issues. First one, 'read_excel' method belongs pandas library and this is not reflected in your question. Additionally, you need to define how many features has your shapefile.POLYLINE. Assuming a polyline with two features, I created a xls file named NI.xls with field code and only two records. So, I also need to define points for each feature:

[-40.5, -20.666],[-39.849998, -18.700001]
[-39.849998, -18.700001],[-39.816002, -19.6]

For avoiding projection issues, I assumed the data for EPSG 4326.

So, with all above assumptions, my code looks as follow:

import shapefile
import pandas as pd

df = pd.read_excel("NI.xls")

df.head()

w = shapefile.Writer(shapefile.POLYLINE)
w.line(parts=[[[-40.5, -20.666],[-39.849998, -18.700001]]])
w.poly(parts=[[[-39.849998, -18.700001],[-39.816002, -19.6]]], shapeType=shapefile.POLYLINE)
w.field('code','C','40')

for i, row in df.iterrows():
    w.record(str(row[0]))

filename = "/home/zeito/pyqgis_data/routeNI7"

w.save(filename)

prj = open("%s.prj" % filename, "w")
epsg = 'GEOGCS["WGS 84",'
epsg += 'DATUM["WGS_1984",'
epsg += 'SPHEROID["WGS 84",6378137,298.257223563]]'
epsg += ',PRIMEM["Greenwich",0],'
epsg += 'UNIT["degree",0.0174532925199433]]'
prj.write(epsg)
prj.close()

After running it at Python Console, I got expected result:

Editing Note:

By using osr osgeo python module, it is easier to define shapefile projection from EPSG:

import shapefile
import pandas as pd
from osgeo import osr

df = pd.read_excel("NI.xls")

df.head()

w = shapefile.Writer(shapefile.POLYLINE)
w.line(parts=[[[-40.5, -20.666],[-39.849998, -18.700001]]])
w.poly(parts=[[[-39.849998, -18.700001],[-39.816002, -19.6]]], shapeType=shapefile.POLYLINE)
w.field('code','C','40')

for i, row in df.iterrows():
    w.record(str(row[0]))

filename = "/home/zeito/pyqgis_data/routeNI7"

w.save(filename)

add_prj = open("%s.prj" % filename, "w")

proj = osr.SpatialReference()
proj.ImportFromEPSG(4326)
epsg = proj.ExportToWkt()

add_prj.write(epsg)
add_prj.close()