topic Re: How to generate grid with offset and assign values to the cells of a the grid? in Mapping Questions

How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Sun, 24 Jun 2018 03:04:33 GMT

I have to generate thousands of cells as a grid, and then I have to assign values to the cells, so far I know the a fishnet tool can generate the grid but how can I manage to create the offset. May some one have better Idea.

The details of the grid are as illustrated in the attached diagram.
I have 5 Rows and 6 column, after the 3rd column the grid should start with B, other numbering should be the same as A.

Re: How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Tue, 26 Jun 2018 18:53:25 GMT

The Only problem I am facing now, is how to generate the grid with offset.

I mean did fishnet support creating the polygons with offset, for each row and column?

Re: How to generate grid with offset and assign values to the cells of a the grid?

XanderBakker — Tue, 26 Jun 2018 18:58:59 GMT

You can use the fishnet as you commented for each block of 32 rectangles, but if you have many blocks you might want to script it using some python code. For that you would need to define the initial coordinate (lower left for instance), the number of blocks horizontally and vertically, the size of each rectangle (width and height) and the spacing between the blocks.

Re: How to generate grid with offset and assign values to the cells of a the grid?

DanPatterson_Retired — Tue, 26 Jun 2018 19:00:17 GMT

No it doesn't, but you could replicate at the new location, but you would have to use the field calculator to replace your coding to represent the new block values.

Beyond that, it would be a coding effort.

Re: How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Tue, 26 Jun 2018 19:12:18 GMT

thanks , yes I do have many blocks, I have to think of that script.

Re: How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Tue, 26 Jun 2018 19:13:18 GMT

Thank you, do you have any code for replicating new location using the field calculator

Re: How to generate grid with offset and assign values to the cells of a the grid?

XanderBakker — Tue, 26 Jun 2018 20:35:59 GMT

If you can provide the following data:

the initial coordinate (lower left for instance),
The spatial reference to be used
the number of blocks horizontally and vertically,
the size of each rectangle (width and height)
the spacing between the blocks

... I'm sure we can help you with that script

Re: How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Wed, 27 Jun 2018 00:14:58 GMT

Thank you Bakker for your help.
the initial coordinate (lower left for instance)= (2523853.5,7124354.1)
The spatial reference to be used (NAD83 / Texas North Central(ftUS) )
the number of blocks horizontally and vertically, (Horizontally 6, Vertically 5
the size of each rectangle (width and height): 40x40ft
the spacing between the blocks: 3ft

after that I need to divide each block to 32 sub sections (w:10ft h:5ft) just like what I have in attached pic, and fill the attribute similar as shown in the attached pic.

Re: How to generate grid with offset and assign values to the cells of a the grid?

XanderBakker — Sun, 12 Dec 2021 07:19:13 GMT

I guess you could use something like this:

def main():
    import arcpy

    # settings
    fc_out = r'C:\GeoNet\RectangleBlocks\data.gdb\result01'
    sr = arcpy.SpatialReference(2276)  # NAD_1983_StatePlane_Texas_North_Central_FIPS_4202_Feet?
    x_start = 2523853.5  # lower left
    y_start = 7124354.1  # lower left
    rect_width = 10.0
    rect_height = 5.0
    num_blocks_h = 6
    num_blocks_v = 5
    num_rect_in_block_h = 4
    num_rect_in_block_v = 8
    spacing_h = 3.0
    spacing_v = 3.0

    rectangles = []

    # loop through blocks
    for block_h in range(num_blocks_h):
        for block_v in range(num_blocks_v):
            # loop through rectangles
            for rect_h in range(num_rect_in_block_h):
                for rect_v in range(num_rect_in_block_v):
                    x_min = x_start + block_h * spacing_h + block_h * num_rect_in_block_h * rect_width + rect_h * rect_width
                    y_min = y_start + block_v * spacing_v + block_v * num_rect_in_block_v * rect_height + rect_v * rect_height
                    x_max = x_min + rect_width
                    y_max = y_min + rect_height
                    rectangle = CreateRactangle(x_min, y_min, x_max, y_max, sr)
                    rectangles.append(rectangle)

    arcpy.CopyFeatures_management(rectangles, fc_out)


def CreateRactangle(x_min, y_min, x_max, y_max, sr):
    coords = [[x_min, y_min], [x_min, y_max], [x_max, y_max],
              [x_max, y_min], [x_min, y_min]]
    return arcpy.Polygon(arcpy.Array([arcpy.Point(*coord) for coord in coords]), sr)

if __name__ == '__main__':
    main()‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Which results in:

Re: How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Wed, 27 Jun 2018 22:43:32 GMT

Yes Yes that's it. Thank you Bakker, I did not test it yet but from code and the result, hat was exactly what I am looking for. its just missing the attribute tables, I will try the field calculator for that.

Will get back to you ASAP.

I do appreciate that

Re: How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Thu, 28 Jun 2018 02:18:18 GMT

Thank you Xander, this worked as supposed to be "smarter".

One last question-is it possible to generate the attribute as requested earlier?.

Thanks Again

Re: How to generate grid with offset and assign values to the cells of a the grid?

XanderBakker — Thu, 28 Jun 2018 13:25:12 GMT

With the attribute table you are referring to labels for each rectangle shown in you image, right?

If so, let's clear up some doubts I have about the coding. Please correct me where I'm wrong.

The code is defined by 3 parts separated by dashes
Part 1 is a character "A" or "B". "A" in case of the 3 first blocks (left) and "B" in case of the last 3 blocks (right)
Part 2 is a number that is defined per quadrant (4x4 rectangles) of each block going from left to right increasing by one. First series 1 to 6 (lower half of first row of blocks), second series (upper part of first row of blocks) 7 to 12, followed by 13 to 18 and 19 to 24 for the second row of blocks, 25 to 30 and 31 to 36 for the third row of blocks, 37 to 42 and 43 to 48 for the fourth row of blocks and 49 to 54 and 55 to 60 for the fifth row of blocks.
Part 3 is a number that will be assigned per quadrant of the blocks, always in the range of 1 to 8, taking the first column of a quadrant and assigning 1 to 4 (starting in the lower rectangle in the quadrant) and 5 to 8 for the second column.

Are these assumptions correct?

Re: How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Thu, 28 Jun 2018 14:22:38 GMT

You are absolutely correct, I mean labeling, and almost exactly right correct in your all other assumptions.

Thank you

Re: How to generate grid with offset and assign values to the cells of a the grid?

XanderBakker — Sun, 12 Dec 2021 07:19:16 GMT

You could try this:

def main():
    import arcpy
    import os

    # settings
    fc_out = r'C:\GeoNet\RectangleBlocks\data.gdb\result04'
    fld_lbl = r'RectangleID'
    sr = arcpy.SpatialReference(2276)  # NAD_1983_StatePlane_Texas_North_Central_FIPS_4202_Feet?

    x_start = 2523853.5  # lower left
    y_start = 7124354.1  # lower left
    rect_width = 10.0
    rect_height = 5.0
    num_blocks_h = 6
    num_blocks_v = 5
    num_rect_in_block_h = 4
    num_rect_in_block_v = 8
    spacing_h = 3.0
    spacing_v = 3.0

    # create output featureclass
    arcpy.env.overwriteOutput = True
    fc_ws, fc_name = os.path.split(fc_out)
    arcpy.CreateFeatureclass_management(fc_ws, fc_name, "POLYGON", None, None, None, sr)

    # add field
    arcpy.AddField_management(fc_out, fld_lbl, "TEXT", None, None, 10)

    # insert cursor
    flds = ("SHAPE@", fld_lbl)
    cnt = 0
    with arcpy.da.InsertCursor(fc_out, flds) as curs:

        # loop through blocks
        for block_h in range(num_blocks_h):
            for block_v in range(num_blocks_v):
                # loop through rectangles
                for rect_h in range(num_rect_in_block_h):
                    for rect_v in range(num_rect_in_block_v):
                        x_min = x_start + block_h * spacing_h + block_h * num_rect_in_block_h * rect_width + rect_h * rect_width
                        y_min = y_start + block_v * spacing_v + block_v * num_rect_in_block_v * rect_height + rect_v * rect_height
                        x_max = x_min + rect_width
                        y_max = y_min + rect_height
                        rectangle = CreateRactangle(x_min, y_min, x_max, y_max, sr)
                        label = GetLabel(block_h, block_v, rect_h, rect_v)
                        cnt += 1
                        if cnt % 50 == 0:
                            print("Processing rectangle: {}".format(cnt))
                        curs.insertRow((rectangle, label, ))

    print("Finished processing {} rectangles".format(cnt))


def CreateRactangle(x_min, y_min, x_max, y_max, sr):
    coords = [[x_min, y_min], [x_min, y_max], [x_max, y_max],
              [x_max, y_min], [x_min, y_min]]
    return arcpy.Polygon(arcpy.Array([arcpy.Point(*coord) for coord in coords]), sr)

def GetLabel(block_h, block_v, rect_h, rect_v):

    even = rect_h % 2 == 0
    if rect_v < 4:
        # lower
        if even:
            part3 = rect_v + 1
        else:
            part3 = rect_v + 5

        quad_row = 1 + 12 * block_v
        if rect_h <2:
            quad_col = block_h * 2
        else:
            # lower right
            quad_col = 1 + block_h * 2
    else:
        if even:
            part3 = rect_v - 3
        else:
            part3 = rect_v + 1
        quad_row = 7 + 12 * block_v
        if rect_h <2:
            quad_col = block_h * 2
        else:
            # lower right
            quad_col = 1 + block_h * 2
    part2 = quad_row + quad_col

    if block_h < 3:
        part1 = "A"
    else:
        part1 = "B"
        part2 = part2 - 6


    return "{}-{}-{}".format(part1, part2, part3)

if __name__ == '__main__':
    main()
‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Which results in:

Re: How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Sun, 12 Dec 2021 07:19:19 GMT

Xander

This script saved my day a couple of times

one line of your script I had never used before.

    return "{}-{}-{}".format(part1, part2, part3)
‍

format is it a method to concatenate string elements.

"Thank you" does not even begin to express the gratitude I have for this help.

Re: How to generate grid with offset and assign values to the cells of a the grid?

DanPatterson_Retired — Fri, 29 Jun 2018 07:47:44 GMT

It has been around for a while...

Read all about it

/blogs/dan_patterson/2016/03/01/basic-fancy-formats

From the Python docs

6.1. string — Common string operations — Python 3.7.0 documentation

Re: How to generate grid with offset and assign values to the cells of a the grid?

XanderBakker — Fri, 29 Jun 2018 12:29:30 GMT

In short the line:

    return "{}-{}-{}".format(part1, part2, part3)‍

... will take a string "{}-{}-{}" and will replace each "{}" by a parameters specified in the format. A very easy and powerful feature of Python. I recommend that you read the documentation provided by the links in Dan_Patterson 's comment.

Re: How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Fri, 29 Jun 2018 12:39:43 GMT

Thank you, for the Useful Link

Re: How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Fri, 29 Jun 2018 12:42:41 GMT

Thanks, Dan Patterson 's comment very useful

Re: How to generate grid with offset and assign values to the cells of a the grid?

HushamMohamed — Sun, 12 Dec 2021 07:19:22 GMT

I am playing around this script, I am not quite well understanding the second part (creating the label - starting from

GetLabel function). If you could put some comments on this parts,
def GetLabel(block_h, block_v, rect_h, rect_v):

    even = rect_h % 2 == 0
    if rect_v < 4:
        # lower
        if even:
            part3 = rect_v + 1
        else:
            part3 = rect_v + 5

        quad_row = 1 + 12 * block_v
        if rect_h <2:
            quad_col = block_h * 2
        else:
            # lower right
            quad_col = 1 + block_h * 2
    else:
        if even:
            part3 = rect_v - 3
        else:
            part3 = rect_v + 1
        quad_row = 7 + 12 * block_v
        if rect_h <2:
            quad_col = block_h * 2
        else:
            # lower right
            quad_col = 1 + block_h * 2
    part2 = quad_row + quad_col

    if block_h < 3:
        part1 = "C"
    else:
        part1 = "D"
        part2 = part2 - 6


    return "{}-{}-{}".format(part1, part2, part3)‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

I am trying to modify this part so the label goes straight through C only without D section and without the offset,

Thank You