pyshp 1.21 unable to write double values for an attribute about pyshp

[jzmiller1]

Could you post more of your code and a zip of your shapefile somewhere if possible?

I'm not having any trouble reading or writing doubles
Here is my shapefile: https://dl.dropboxusercontent.com/u/77727653/points.zip
Here is some example code:

import shapefile
f = shapefile.Editor('shapefiles/points.shp')
for r in f.records:
    if r[1] == 0.0:
        r[1] = 9.9
for r in f.records:
    print(r)

f.save('shapefiles/junk')

[apiszcz]

import sys
sys.path.append('lib')
import shapefile
w=shapefile.Writer(shapefile.POINT)
w.point(1,1)
w.field('DOUBLETEST','N','8')
w.record('DOUBLETEST',1234567890123.0)
w.save('doubletest')

Traceback (most recent call last):
File "C:\p\test\pyshptest.py", line 8, in
w.save('doubletest')
File "lib\shapefile.py", line 1032, in save
self.saveDbf(target)
File "lib\shapefile.py", line 1004, in saveDbf
self.__dbfRecords()
File "lib\shapefile.py", line 891, in __dbfRecords
assert len(value) == size
AssertionError

[jzmiller1]

Looks like you are giving a double larger than the size you allowed in the field creation. You specified 8 but the double is larger. Try this instead:

import sys
sys.path.append('lib')
import shapefile
w=shapefile.Writer(shapefile.POINT)
w.point(1,1)
w.field('DOUBLETEST','N','14')
w.record('DOUBLETEST',1234567890123.0)
w.save('doubletest')

[apiszcz]

That corrects the initial stack trace however the value is 0.

The 2nd line from the bottom DOUBLETEST (Real) = 0

import sys
sys.path.append('lib')
import shapefile
w=shapefile.Writer(shapefile.POINT)
w.point(1,1)
w.field('DOUBLETEST','N','14')
w.record('DOUBLETEST',1234567890123.0)

w.save('doubletest')

C:\p\test>ogrinfo -al doubletest.shp
INFO: Open of doubletest.shp' using driverESRI Shapefile' successful.

Layer name: doubletest
Geometry: Point
Feature Count: 1
Extent: (1.000000, 1.000000) - (1.000000, 1.000000)
Layer SRS WKT:
(unknown)
DOUBLETEST: Real (16.0)
OGRFeature(doubletest):0
DOUBLETEST (Real) = 0
POINT (1 1)

On Wed, Sep 3, 2014 at 2:37 PM, Zac Miller [email protected] wrote:

Looks like you are giving a double larger than the size you allowed in the
field creation. You specified 8 but the double is larger. Try this instead:

import sys
sys.path.append('lib')
import shapefile
w=shapefile.Writer(shapefile.POINT)
w.point(1,1)
w.field('DOUBLETEST','N','14')
w.record('DOUBLETEST',1234567890123.0)
w.save('doubletest')

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#7 (comment)
.

[jzmiller1]

Try this:

w = shapefile.Writer(shapefile.POINT)
w.point(1,1)
w.field('DOUBLETEST', 'N', '17', 2)
w.record(DOUBLETEST=1234567890123.0)
w.save('doubletest')

Or this:

w = shapefile.Writer(shapefile.POINT)
w.point(1,1)
w.field('DOUBLETEST', 'N', '17', 2)
w.record(1234567890123.0)
w.save('doubletest')

If you do it the first way your data gets collected into recordDict, if you do it the second way it gets collected into recordList of the Editor record method:

def record(self, *recordList, **recordDict):
        """Creates a dbf attribute record. You can submit either a sequence of
        field values or keyword arguments of field names and values. Before
        adding records you must add fields for the record values using the
        fields() method. If the record values exceed the number of fields the
        extra ones won't be added. In the case of using keyword arguments to specify
        field/value pairs only fields matching the already registered fields
        will be added."""
        record = []
        fieldCount = len(self.fields)
        # Compensate for deletion flag
        if self.fields[0][0].startswith("Deletion"): fieldCount -= 1
        if recordList:
            [record.append(recordList[i]) for i in range(fieldCount)]
        elif recordDict:
            for field in self.fields:
                if field[0] in recordDict:
                    val = recordDict[field[0]]
                    if val is None:
                        record.append("")
                    else:
                        record.append(val)
        if record:
            self.records.append(record)

[apiszcz]

Both work, any way those examples can be added to the documentation (if
needed), or did I miss something. Thank you.

On Wed, Sep 3, 2014 at 3:09 PM, Zac Miller [email protected] wrote:

Try this:

w = shapefile.Writer(shapefile.POINT)
w.point(1,1)
w.field('DOUBLETEST', 'N', '17', 2)
w.record(DOUBLETEST=1234567890123.0)
w.save('doubletest')

Or this:

w = shapefile.Writer(shapefile.POINT)
w.point(1,1)
w.field('DOUBLETEST', 'N', '17', 2)
w.record(1234567890123.0)
w.save('doubletest')

If you do it the first way your data gets collected into recordDict, if
you do it the second way it gets collected into recordList of the Editor
record method:

def record(self, _recordList, *_recordDict):
"""Creates a dbf attribute record. You can submit either a sequence of
field values or keyword arguments of field names and values. Before
adding records you must add fields for the record values using the
fields() method. If the record values exceed the number of fields the
extra ones won't be added. In the case of using keyword arguments to specify
field/value pairs only fields matching the already registered fields
will be added."""
record = []
fieldCount = len(self.fields)
# Compensate for deletion flag
if self.fields[0][0].startswith("Deletion"): fieldCount -= 1
if recordList:
[record.append(recordList[i]) for i in range(fieldCount)]
elif recordDict:
for field in self.fields:
if field[0] in recordDict:
val = recordDict[field[0]]
if val is None:
record.append("")
else:
record.append(val)
if record:
self.records.append(record)

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#7 (comment)
.

[jzmiller1]

If I have time I will try to look over the docs and put together a pull request with another example.

[riggsd]

Whether the user is doing something wrong or not, I think that this isn't an appropriate use of assert() in library code. Here's a PR to throw an exception instead:

#17

[karimbahgat]

So the original issue here was caused by the field length being too short for the value.

Another issue was that w.record(DOUBLETEST=1234567890123.0) was mistyped as w.record('DOUBLETEST',1234567890123.0).

As for the doc additions, I didn't fully understand which parts were desired, but record keyword assignment are already featured in the docs, and #73 suggests adding more examples on data types.

And the assert has been changed to a more informative exception.

Considering this resolved.