I was trying to read a data file to an array which include float and string.
metadata = genfromtxt('iris_labels.tsv',delimiter='\t', dtype=str)
print(metadata)
Which give me
is that possible to ignore the ('') sign?
Not a numpy expert and I haven't tried it out but I think you're looking for something like
my_dtype=np.dtype([
('petal.w', np.float),
('petal.h', np.float),
('sepal.w', np.float),
('sepal.h', np.float),
('species', 'a32')
])
p.s. I don't know the actual order of your columns
Related
From my understanding, and I am probably wrong here, but doesn't the ISNUMERIC() return a 1 if whatever we are looking at is a numeric data type? And since most zip codes are saved as varchar data types, shouldn't it then return a 0? I looked up the documentation and that's what it says there to me, what am I missing here? I get zip codes are numbers, but because they are saved as a string shouldn't that make a difference? Thanks in advance.
ISNUMERIC() is specifically to look at strings, not at things already stored as numbers.
However, I don't recommend using it. For instance, '3.1e5' is considered numeric.
Instead, use try_convert():
try_convert(int, zip)
This returns NULL if the column cannot be converted.
I'm aware of the option to output a query formatted as JSON, like the following example from the from MSDN page:
SELECT name, surname
FROM emp
FOR JSON AUTO
There are a lot of samples on how to use the resulting json from apps but my question is, how can I store the resulting json in a varchar variable, let's say to store in another table?
DECLARE #Json nvarchar(MAX) = (
SELECT name, surname
FROM emp
FOR JSON AUTO
);
Dan Guzman replied in the MSDN Forum with this neat solution, which corresponds also to #FDavidov's suggestion in his last comment
A JSON is, in fact, a character string. What makes this character string to be a JSON is the combination of two things:
You refer to it as a JSON (using the correct functions within your environment),
It contains the correct delimiters at the correct locations to comply with the rules of a JSON.
So, if you want to store a JSON in a variable, just assign to the variable the source string and, whenever you want to act on your variable, just remember it is a JSON.
I am using PostgreSQL 9.4.1 and have run into an issue with a column that I need to update. The column is of type JSON with elements in the following format:
["a","b","c",...]
["a","c","d",...]
["c","d","e",...]
etc.
so that each element is a string. It is my understanding that each of these elements are considered keys to the JSON array (please correct me if I am a bit confused here, I haven't ever worked with JSON datatype columns before, so I'm still trying to get a grip on them anyways). There is not an actual pattern to these arrays, and their contents are dependent on user input from somewhere else. My goal is to update any of the arrays that contain a particular element (say "b" for the purpose of explaining my question more thoroughly) and replace the content "b" with say "b1". Meaning that:
["a","b","c",...]
would be updated to
["a","b1","c",...]
I have found a few ways listed on this site (I don't currently have the links, but I can find them again if necessary) to update VALUES for a particular KEY, but I haven't found a way mentioned to change the KEY itself. I have already found a way to target the specific rows of interest by doing something similar to:
SELECT *
FROM TableA
WHERE column::json ?| ["b", other string elements of interest]
Any suggestions would be greatly appreciated. Thanks for your help!
So I went ahead and gave that a check (because it looks like it should work, and it's more or less what I ended up doing), but I figured out what I was trying to do! What I got was this:
UPDATE TableA
SET column = REPLACE(column::TEXT,'b','b1')::JSON
WHERE column::JSON ?| ['b']
And now that I think about it, I probably don't even need the last where condition because the replace won't affect anything that doesn't have 'b' in it. But that worked for me, and it looks like yours probably should too! Thanks for the help!
I wanted to rename a specific key for json array column.
I tried and it worked on PostgreSQL 9.4:
UPDATE Your_Table_Name
SET Your_Column_Name = replace(Your_Column_Name::TEXT,'Key_Old_Name','Key_New_Name')::json
WHERE attributes::jsonb ? 'Key_Old_Name'
Basically, solution is to go over the list of json_array_elements, and based on json value using CASE condition replace certain value with other one. After all, need to re-build new json array using array_agg() and to_json() description of aggregate functions in psql is here.
Possible query can be the following:
-- Sample DDL and JSON data
CREATE TABLE jsontest (data JSON);
INSERT INTO jsontest VALUES ('["a","b","c"]'::JSON);
-- QUERY
WITH result AS (
SELECT to_json( -- creating updated json structure
array_agg( -- create array with new element "b1"
CASE WHEN element::TEXT = '"b"' -- here we process array elements to find "b"
THEN to_json('b1'::TEXT)
ELSE element
END)) as new_json
FROM jsontest,json_array_elements(jsontest.data) as element
)
UPDATE jsontest SET data = result.new_json FROM result;
I needed to insert an array field into a database and I was pleased to notice that PostGreSQL had that functionality. But now I am not able to insert the data using the tables active record.
I have tried the below calls with no success
$active_record->array_column = $_array_of_values;
which gives me the exception
Exception Raised:CDbCommand failed to execute the SQL statement: SQLSTATE[22P02]: Invalid text representation: 7 ERROR: array value must start with "{" or dimension information
I have also tried this using
foreach($_array_of_values as $value){
$active_record->array_column[] = $value;
}
which tells me
Indirect modification of overloaded property FeatureRaw::$colors_names has no effect
Can anyone help me with this?
Thanks!
Data must be inserted in the form (text representation of an ARRAY):
INSERT INTO tbl (arr_col) VALUES ('{23,45}')
Or:
INSERT INTO tbl (arr_col) VALUES ('{foo,"bar, with comma"}')
So you need to enclose your array values in '{}' and separate them with comma ,. Use double quotes "" around text values that include a comma.
I listed more syntax variants to insert arrays in a related answer.
For those who also have same problem:
I didn't check the Yii1 behavior, but in Yii2 you simply can insert array as properly formed string as Erwin Brandstetter mentioned in his comment:
$activeRecord->arrayField = '{' . implode(',',$array_values) . '}';
Of course you need to make additional efforts when your $array_values has strings with commas, etc. And you still need to convert value back to array after you load ActiveRecord.
You can make these conversions in ActiveRecord's beforeSave() and afterLoad() and you will not need to convert values manually.
UPD. Recently I made a simple behavior for Yii2 to use array fields with ActiveRecord without manual field building: kossmoss/yii2-postgresql-array-field. It is more generalized way to solve the problem and I hope it will help. For those who use Yii1: you can investigate the package code and create your own solutuion compatible with your framework.
I have currently a dataset which contains the variables I need together with the needed formats.
Now I am using the getvarc() function (among others) in a loop to get those variables to write to a file.
The first problem occuring ofcourse, is that some variables are not char type but num type. I could use getvarn() to retrieve those, but then the format goes to waste which I really need.
E.g. date in num type: 18750. Format = yymmdd10. Thus looking like 2011-05-03
Using the value=getvarn() for this field, it would retrieve 18750 for value. If I then want to output (using PUT) this value, it would not give me the 2011-05-03 date as I want.
So now I am looking for a better way to do this.
My first option is to use the sashelp.vcolumn data set, to retrieve the format on this field, and use it in the put statement to output in the right format.
My second option is to convert the data set containing this field (in reality it is about multiple data sets), where I convert all num type fields to char types remaining the right format.
Which option should I go with?
And in case of the second option, can this be done in a generic way (as I said, this is not about one variable only) ?
EDIT:
After the answer of Cmjohn I got to find a way to fix my problem. Not using the sashelp.vcolumn but using the varfmt function.
So a short explanation of what I am doing in my code:
data _null_
set dataset1;
file file1;
if somefield = x then do;
dsid = open(datasetfield, i);
rc = fetchobs (dsid);
varnum = varnum(dsid,anotherfield);
**varfmt = varfmt(dsid,anotherfield);
if vartype(dsid,anotherfield) = 'N' then do;**
value = getvarn(dsid,varnum);
**value_formatted = putn(value,varfmt);**
**end;
else do;**
value = getvarc(dsid,varnum);
**value_formatted = putc(value,varfmt);
end;**
put value_formatted;
end;
run;
So this is in general (quickly out of my head) what I am doing now. The bold part of the solution is what I came up with after Cmjohns response. So my first question is answered, 'How to do it?'.
But my added question: What would be most efficient in the long run: keep this process or make my data sets the way that all data can be read in by only using getvarc without the need of the type-check and the getfmt()?
I'd suggest that you use the vvalue function, or any of the other techniques provided in the answers to this question to put formatted values to a file.