Hopefully a simple question with Lua. I have a problem accessing JSON data. I write the following:
item3 = decoded.items[1].rights
local myText = display.newText(sceneGroup, item3, 150, 80, native.systemFont, 16 )
myText:setFillColor( 1, 1, 1 )
But error comes up
C:\Users\...\data_workingbasics.lua:57: bad argument #2 to 'newText' (string expected, got table)
stack traceback:
[C]: in function 'newText'
I think the problem is JSON data looks like below and I don't know how to fetch this data with square brackets.
Do you know how to write the right path?
"rights":["http://creativecommons.org/licenses/by-nc-sa/4.0/"],
By the way, I also tried item3 = decoded.items[1].rights[0] but get the following error:
C:\Users\...\data_workingbasics.lua:57: bad argument #2 to 'newText' (string expected, got nil)
stack traceback:
[C]: in function 'newText'
Many thanks!
It may be item3 = decoded.items[1].rights["rights"]. If not, use some old-fashioned debugging and add print statements to display properties of the table. For example:
print(#decoded.items[1].rights)
Or iterate through the tables keys and values to see its structure:
for k, v in pairs(decoded.items[1].rights) do
print(k, v)
end
Determine what you are working with.
Related
Following script describes the decoding of a JSON Object, that is received via MQTT. In this case, we shall take following JSON Object as an example:
{"00-06-77-2f-37-94":{"publish_topic":"/stations/test","sample_rate":5000}}
After being received and decoded in the handleOnReceive function, the local function saveTable is called up with the decoded object which looks like:
["00-06-77-2f-37-94"] = {
publish_topic = "/stations/test",
sample_rate = 5000
}
The goal of the saveTable function is to go through the table above and assign the values "/stations/test" and 5000 respectively to the variables pubtop and rate. When I however print each of both variables, nil is returned in both cases.
How can I extract the values of this table and save them in mentioned variables?
If i can only save the values "publish_topic = "/stations/test"" and "sample_rate = 5000" at first, would I need to parse these to get the values above and save them, or is there another way?
local pubtop
local rate
local function saveTable(t)
local conversionTable = {}
for k,v in pairs(t) do
if type(v) == "table" then
conversionTable [k] = string.format("%q: {", k)
printTable(v)
print("}")
else
print(string.format("%q:", k) .. v .. ",")
end
end
pubtop = conversionTable[0]
rate = conversionTable[1]
end
local lua_value
local function handleOnReceive(topic, data, _, _)
print("handleOnReceive: topic '" .. topic .. "' message '" .. data .. "'")
print(data)
lua_value = JSON:decode(data)
saveTable(lua_value)
print(pubtop)
print(rate)
end
client:register('OnReceive', handleOnReceive)
previous question to thread: Decode and Parse JSON to Lua
The function I gave you was to recursively print table contents. It was not ment to be modified to get some specific values.
Your modifications do not make any sense. Why would you store that string in conversionTable[k]? You obviously have no idea what you're doing here. No offense but you should learn some basics befor you continue.
I gave you that function so you can print whatever is the result of your json decode.
If you know you get what you expect there is no point in recursively iterating through that table.
Just do it like that
for k,v in pairs(lua_value) do
print(k)
print(v.publish_topic)
print(v.sample_rate)
end
Now read the Lua reference manual and do some beginners tutorials please.
You're wasting a lot of time and resources if you're trying to implement things like that if you do not know how to access the elements of a table. This is like the most basic and important operation in Lua.
I have a lua script with many tables like
local a = {1,2,3}
local b = {1,2,3}
local c = {1,2,3}
etc. and one function like
test = {}
function test.set(args)
for x, y in pairs(args) do
....
end
end
test[arg[1]](arg[2])
Now I want to choose one of the tables via command line to use it in the function. I tried
lua MyScript.lua set a
and I get the error
lua: MyScript.lua:1249: bad argument #1 to 'pairs' (table expected, got string)
stack traceback:
[C]: in function 'pairs'
MyScript.lua:1249: in field '?'
MyScript.lua:1266: in main chunk
[C]: in ?
It kind of makes sense because I pass a string. But I don't know how to select the table I want to use in the function. Can anybody help me?
local all_your_tables = {a = {1,2,3}, b = {1,2,3}, c = {1,2,3}}
...
test[arg[1]](all_your_tables[arg[2]])
I know that I can use LIST_TO_ASCI to convert a report to ASCII, but I would like to have a more high level data format like JSON, XML, CSV.
Is there a way to get something that is easier to handle then ASCII?
Here is the report I'd like to convert:
The conversion needs to be executed in ABAP on a result which was executed like this:
SUBMIT <REPORT_NAME> ... EXPORTING LIST TO MEMORY AND RETURN.
You can get access to SUBMIT list in memory like this:
call function 'LIST_FROM_MEMORY'
TABLES
listobject = t_list
EXCEPTIONS
not_found = 1
others = 2.
if sy-subrc <> 0.
message 'Unable to get list from memory' type 'E'.
endif.
call function 'WRITE_LIST'
TABLES
listobject = t_list
EXCEPTIONS
EMPTY_LIST = 1
OTHERS = 2
.
if sy-subrc <> 0.
message 'Unable to write list' type 'E'.
endif.
And the final step of the solution (conversion of result table to JSON) was already answered to you in your question.
I found a solution here: http://zevolving.com/2015/07/salv-table-22-get-data-directly-after-submit/
This is the code:
DATA: lt_outtab TYPE STANDARD TABLE OF alv_t_t2.
FIELD-SYMBOLS: <lt_outtab> like lt_outtab.
DATA lo_data TYPE REF TO data.
" Let know the model
cl_salv_bs_runtime_info=>set(
EXPORTING
display = abap_false
metadata = abap_false
data = abap_true
).
SUBMIT salv_demo_table_simple
AND RETURN.
TRY.
" get data from SALV model
cl_salv_bs_runtime_info=>get_data_ref(
IMPORTING
r_data = lo_data
).
ASSIGN lo_data->* to <lt_outtab>.
BREAK-POINT.
CATCH cx_salv_bs_sc_runtime_info.
ENDTRY.
Big thanks to Sandra Rossi, she gave me the hint to cx_salv_bs_sc_runtime_info.
Related answer: https://stackoverflow.com/a/52834118/633961
I am trying to compile monthly data in to an existing JSON file that I loaded via import json. Initially, my json data just had one property which is 'name':
json_data['features'][1]['properties']
>>{'name':'John'}
But the end result with the monthly data I want is like this:
json_data['features'][1]['properties']
>>{'name':'John',
'2016-01': {'x1':0, 'x2':0, 'x3':1, 'x4':0},
'2016-02': {'x1':1, 'x2':0, 'x3':1, 'x4':0}, ... }
My monthly data are on separate tsv files. They have this format:
John 0 0 1 0
Jane 1 1 1 0
so I loaded them via import csv and parsed through a list of urls and set about placing them in a collective dictionary like so:
file_strings = ['2016-01.tsv', '2016-02.tsv', ... ]
collective_dict = {}
for i in strings:
with open(i) as f:
tsv_object = csv.reader(f, delimiter='\t')
collective_dict[i[:-4]] = rows[0]:rows[1:5] for rows in tsv_object
I checked how things turned out by slicing collective_dict like so:
collective_dict['2016-01']['John'][0]
>>'0'
Which is correct; it just needs to be cast into an integer.
For my next feat, I attempted to assign all of the monthly data to the respective json members as part of their external properties:
for i in file_strings:
for j in range(len(json_data['features'])):
json_data['features'][j]['properties'][i[:-4]] = {}
json_data['features'][j]['properties'][i[:-4]]['x1'] = int(collective_dict[i[:-4]][json_data['features'][j]['properties']['name']][0])
json_data['features'][j]['properties'][i[:-4]]['x2'] = int(collective_dict[i[:-4]][json_data['features'][j]['properties']['name']][1])
json_data['features'][j]['properties'][i[:-4]]['x3'] = int(collective_dict[i[:-4]][json_data['features'][j]['properties']['name']][2])
json_data['features'][j]['properties'][i[:-4]]['x4'] = int(collective_dict[i[:-4]][json_data['features'][j]['properties']['name']][3])
Here I got an arrow pointing at the last few characters:
Syntax Error: unexpected EOF while parsing
It is a pretty complicated slice, I suppose user error is not to be ruled out. However, I did double and triple check things. I also looked up this error. It seems to come up with input() related calls. I'm left a bit confused, I don't see how I made a mistake (although I'm already mentally prepared to accept that).
My only guess was that something somewhere was not a string. When I checked collective_dict and json_data, everything that was supposed to be a string was a string ('John', 'Jane' et all). So, I guess it's something else.
I made the problem as simple as I could while keeping the original structure of the data and for loops and so forth. I'm using Python 3.6.
Question
Why am I getting the EOF error? How can I build my external properties data without encountering such an error?
Here I have rewritten your last code block to:
for i in file_strings:
file_name = i[:-4]
for j in range(len(json_data['features'])):
name = json_data['features'][j]['properties']['name']
file_dict = json_data['features'][j]['properties'][file_name] = {}
for x in range(4):
x_string = 'x{}'.format(x+1)
file_dict[x_string] = int(collective_dict[file_name][name][x])
from:
for i in file_strings:
for j in range(len(json_data['features'])):
json_data['features'][j]['properties'][i[:-4]] = {}
json_data['features'][j]['properties'][i[:-4]]['x1'] = int(collective_dict[i[:-4]][json_data['features'][j]['properties']['name']][0])
json_data['features'][j]['properties'][i[:-4]]['x2'] = int(collective_dict[i[:-4]][json_data['features'][j]['properties']['name']][1])
json_data['features'][j]['properties'][i[:-4]]['x3'] = int(collective_dict[i[:-4]][json_data['features'][j]['properties']['name']][2])
json_data['features'][j]['properties'][i[:-4]]['x4'] = int(collective_dict[i[:-4]][json_data['features'][j]['properties']['name']][3])
That is just to make it a bit more readable, but that shouldn't change anything.
A thing I noticed in your other part of code is the following:
collective_dict[i[:-4]] = rows[0]:rows[1:5] for rows in tsv_object
The thing I refer to is the = rows[0]:rows[1:5] for rows in tsv_object part. In my IDE, that does not work, and I'm not sure if that is a typo in your question or of that is actually in your code, but I imagine you want it to actually be
collective_dict[i[:-4]] = {rows[0]:rows[1:5] for rows in tsv_object}
or something like that. I'm not sure if that could confuse the parser think that there is an error at the end of the file.
The ValueError: Invalid literal for int()
If your tsv-data is
John 0 0 1 0
Jane 1 1 1 0
Then it should be no problem to do int() of the string value. E.g.: int('42') will become an int with value 42. However, if you have an error in one, or several, lines of your files, then use something like this block of code to figure out which file and line it is:
file_strings = ['2016-01.tsv', '2016-02.tsv', ... ]
collective_dict = {}
for file_name in file_strings:
print('Reading {}'.format(file_name))
with open(file_name) as f:
tsv_object = csv.reader(f, delimiter='\t')
for line_no, (name, *x_values) in enumerate(tsv_object):
if len(x_values) != 4:
print('On line {}, there is only {} values!'.format(line_no, len(x_values)))
try:
intx = [int(x) for x in x_values]
except ValueError as e:
# Catch "Invalid literal for int()"
print('Line {}: {}'.format(line_no, e))
This question was given to me during an interview. The interview is long over, but I'm still thinking about hte problem and its bugging me:
You have a language that contains the following tools: a rand() function, while and for loops, if statements, and a readline() method (similar to python's readline()). Given these tools, write an algorithm that returns a random line in the file. You don't know the size of the file, and you can only loop over the file's contents once.
I don't know the desired answer, but my solution would be the following:
chosen_line = ""
lines = 0
while (current_line = readline()):
if (rand(0, lines) == 0):
chosen_line = current_line
lines++
return chosen_line
Edit: A good explanation why this works was posted in this comment.
One method, guaranteeing a uniform distribution:
(1) Read the file line-by-line into an array (or similar, e.g. python list)
(2) Use rand() to select a number between 0 and largest index in the array.
Another, not guaranteeing a uniform distribution:
Read each line. On each read, also call rand(). If over a threshold, return the line.
Although similar to Marcin's third option, Luc's implementation always returns the first line, while parsing the whole file.
It should be something like:
chosen_line = ""
treshold = 90
max = 100
while chosen_line == "":
current_line = readline()
if (rand(0, max) > treshold):
chosen_line = current_line
print chosen_line
You could also return current_line in the case no line was chosen and you read the whole file.