Probably simple syntax error

**Gary Herron** · Jul 2 '07, 05:05 AM

Re: Probably simple syntax error

Dustin MacDonald wrote:

Hi everyone.
>
This is my first time posting to this newsgroup, and although I
maintain my netiquette I might've missed something specific to the
newsgroup, so hopefully you can avoid flaming me if I have :) I
apologize for the length of this post but I figure the more
information the better.
>
My problem is that I'm getting a syntax error in some Python code that
looks quite simple. The original code was in Object Pascal as I'm a
recent Delphi-turned-Python programmer.
>
I took the code (which is only about 130 lines in OP) and 'translated'
it the best I could into Python (ended up being one line shy of 80
when I was done). I can't see any problems with the code but it's
coming up with a bunch of errors, which I'm guessing are probably my
assuming something is the same in Python as it is in Pascal, and being
wrong.
>
Anyway, here's the code I'm having trouble with (the same error comes
up several times but this is the first part of the code it shows up
in):
>

Code:

randomizing_counter = 0
# Put the loop counter for the randomizing to zero.
until_val = 36
# Set the "until val" to 36. We'll compare them to make sure we're not
at the end of our wordlist_both.
>
while randomizing_counter < until_val:
	big_randomized_int = RandRange(0,100)
	# Make a random value and store it.
	small_randomized_int = big_randomized_int / 100
	# Divide that random value and store it in a different variable.
	small_randomized_int = Round(small_randomized_int, 2)
	# Round that value to 2 decimal places
	**weights_array(randomizing_counter) = small_randomized_int
>

Code:

If  weights_array is a list or dictionary then use
weights_array[randomizing_counter] = ...
to choose which element of the list gets the assignment.

If weights_array is a function, then
weights_array(randomizing_counter)
is the proper way to call the function, but the value returned cannot be
the object of an assignment.

Gary Herron
[QUOTE]
	# Assign the first randomized value to our first word to be weighted.
	randomizing_counter = randomizing_counter + 1
	# Up the counter and repeat.
[/QUOTE]

>
The starred line is the one getting the error message: "SyntaxErro r:
can't assign to function call"
>
Now, I do understand what this means. I'm trying to assign to a
function instead of the value that the function should create. But
since when is weights_array or small_randomizi ng_int a function? Both
are being declared in the code on their first usage. This one has got
me stumped, maybe you guys can help me out with it?
>
Thanks,
~Dustin
>
>

**Mark Peters** · Jul 2 '07, 05:15 AM

Re: Probably simple syntax error

**weights_array (randomizing_co unter) = small_randomize d_int

>
The starred line is the one getting the error message: "SyntaxErro r:
can't assign to function call"
>
Now, I do understand what this means. I'm trying to assign to a
function instead of the value that the function should create. But
since when is weights_array or small_randomizi ng_int a function? Both
are being declared in the code on their first usage. This one has got
me stumped, maybe you guys can help me out with it?

Using parens () indicates a function call.

I suspect things will work much better using square brackets [].

Square brackets indicate the index into a sequence (like a list)

**John Machin** · Jul 2 '07, 09:25 AM

Re: Probably simple syntax error

On Jul 2, 2:40 pm, Dustin MacDonald <dmacdonal...@g mail.comwrote:

Hi everyone.
>
This is my first time posting to this newsgroup, and although I
maintain my netiquette I might've missed something specific to the
newsgroup, so hopefully you can avoid flaming me if I have :) I
apologize for the length of this post but I figure the more
information the better.

The more relevant information the better. It would have helped had you
shown (a) the first use of weights_array (b) your import statements

>
My problem is that I'm getting a syntax error in some Python code that
looks quite simple. The original code was in Object Pascal as I'm a
recent Delphi-turned-Python programmer.
>
I took the code (which is only about 130 lines in OP) and 'translated'
it the best I could into Python (ended up being one line shy of 80
when I was done). I can't see any problems with the code but it's
coming up with a bunch of errors, which I'm guessing are probably my
assuming something is the same in Python as it is in Pascal, and being
wrong.
>
Anyway, here's the code I'm having trouble with (the same error comes
up several times but this is the first part of the code it shows up
in):

Others have pointed out that the likely source of your first problem
is using () instead of [] for list subscripting.

I'll move on to the next few ...

>

Code:

randomizing_counter = 0
# Put the loop counter for the randomizing to zero.

Code:

Problem 2: excessive verbosity
[QUOTE]
until_val = 36
# Set the "until val" to 36. We'll compare them to make sure we're not
at the end of our wordlist_both.
>
while randomizing_counter < until_val:[/QUOTE]

Try this:

weights_array = []
assert len(wordlist_both) == 36 # ???
for _unused in range(len(wordlist_both)):
# calculate something
weights_array.append(something)

[QUOTE]
        big_randomized_int = RandRange(0,100)[/QUOTE]

Problem 3a:
You have an import statement like
import random
in which case you would get a runtime error, and should have:
.... = random.randrange(0, 100)
or Problem 3b:
You have an import statement like:
from random import randrange as RandRange
which will not cause a runtime error, merely mass barfing among the
spectators :-)
[QUOTE]
        # Make a random value and store it.
        small_randomized_int = big_randomized_int / 100[/QUOTE]

Problem 5: putting comments after the code instead of on the same line
as the statement you think needs explanation (most don't) or before
it.
[QUOTE]
        # Divide that random value and store it in a different variable.[/QUOTE]

Problem 6: big_randomized_int can only have values in 0, 1, ..., 98,
99. So small_randomized_int will have the value 0, always.

Perhaps you meant:
small_randomised_float = big_randomized_int / 100.0
[QUOTE]
        small_randomized_int = Round(small_randomized_int, 2)
        # Round that value to 2 decimal places[/QUOTE]

Problem 7: even if you did intend big.... / 100.00, the above is
redundant. 1 / 100.0 is 0.01, 99 / 100.0 is 0.99 -- no rounding is
necessary.

Problem 8: it's round(), not Round()
[QUOTE]
        **weights_array(randomizing_counter) = small_randomized_int
        # Assign the first randomized value to our first word to be weighted.[/QUOTE]

First? It's done each time around the loop.
[QUOTE]
        randomizing_counter = randomizing_counter + 1
        # Up the counter and repeat.
[/QUOTE]

>

So, here's the looping version:

weights_array = []
for _unused in range(len(wordl ist_both)):
weights_array.a ppend(random.ra ndrange(100) / 100.0)

and here's the obligatory one-liner, using a list comprehension:

weights_array = [random.randrang e(100) / 100.0 for _unused in
range(len(wordl ist_both))]

and here's an example of it in use:

>>import random
>>wordlist_bo th = 10 * ['foo']
>>weights_arr ay = [random.randrang e(100) / 100.0 for _unused in range(len(wordl ist_both))]
>>weights_arr ay

[0.38, 0.12, 0.5500000000000 0004, 0.2399999999999 9999,
0.9100000000000 0003, 0.4899999999999 9999, 0.9100000000000 0003,
0.6700000000000 0004, 0.7700000000000 0002,
0.8199999999999 9995]

>>>

Problem 9: you were expecting "precise" values like 0.55 and 0.24.

Solution is to read this:

404 Not Found

http://docs.python.org/tut/node16.html

HTH,
John

**ptn** · Jul 2 '07, 02:35 PM

Re: Probably simple syntax error

>
Problem 6: big_randomized_ int can only have values in 0, 1, ..., 98,
99. So small_randomize d_int will have the value 0, always.
>
Perhaps you meant:
small_randomise d_float = big_randomized_ int / 100.0
>

small_randomize d_int = Round(small_ran domized_int, 2)
# Round that value to 2 decimal places

>

PASCAL -- PYTHON
5 div 2 -- 5/2
5 mod 2 -- 5 % 2
5/2 -- 5/2. (Notice the little dot at the end)

**Cameron Laird** · Jul 2 '07, 05:15 PM

Re: Probably simple syntax error

In article <1183352843.803 263.82140@57g20 00hsv.googlegro ups.com>,
Mark Peters <mpeters42@gmai l.comwrote:

**Dustin MacDonald** · Jul 2 '07, 11:05 PM

Re: Probably simple syntax error

Ah. Thank you everyone. Sorry for not replying earlier, real life got
in the way :)

Gerry Herron, Tim Delaney, Mark Peters: Thank you. Switching from
parentheses to square brackets fixed the code, and yes, Tim, you were
right. It was a list I was working with. And thanks for those links
Tim.

John Machin: Thank you for all the pointers/code fixes there. They'll
help alot.

Ptn: I was unaware of that period added, Thanks, I'll have to watch
out for it. :)

And Cameron: Ah, yes. It does reduce the confusion. I do know that
square brackets are used for *creating* a dictionary (blah = ["A",
"B", "C"], so I figured the same would apply to accessing it (which is
why for my list, which I created with parenthesis I assumed I accessed
with parenthesis). Thank you =]

~Dustin

**Duncan Booth** · Jul 3 '07, 08:05 AM

Re: Probably simple syntax error

ptn <tn.pablo@gmail .comwrote:

PASCAL -- PYTHON
5 div 2 -- 5/2

better: 5//2

The behaviour of 5/2 varies according to command line options and/or
__future__ imports. e.g. If you start Python with the -Qwarn option 5/2
will generate a warning; if you start Python with -Qnew (or use "from
__future__ import division") then 5/2 will give you 2.5.

It is best, if you mean integer division, to always use the integer
division operator.

5 mod 2 -- 5 % 2
5/2 -- 5/2. (Notice the little dot at the end)

Also note that those relationships only hold where both operands are
positive.

Python: -3//2 ----2
Pascal: -3 div 2 ---either -1 or -2 is allowed by the standard.

Python: 3 % -2 ----1
Pascal: 3 mod -2 --error

Probably simple syntax error

Probably simple syntax error

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