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Top Questions People Ask About Pandas, NumPy, Matplotlib & Scikit-learn — Answered!

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 Whether you're a beginner or brushing up on your skills, these are the real-world questions Python learners ask most about key libraries in data science. Let’s dive in! 🐍 🐼 Pandas: Data Manipulation Made Easy 1. How do I handle missing data in a DataFrame? df.fillna( 0 ) # Replace NaNs with 0 df.dropna() # Remove rows with NaNs df.isna(). sum () # Count missing values per column 2. How can I merge or join two DataFrames? pd.merge(df1, df2, on= 'id' , how= 'inner' ) # inner, left, right, outer 3. What is the difference between loc[] and iloc[] ? loc[] uses labels (e.g., column names) iloc[] uses integer positions df.loc[ 0 , 'name' ] # label-based df.iloc[ 0 , 1 ] # index-based 4. How do I group data and perform aggregation? df.groupby( 'category' )[ 'sales' ]. sum () 5. How can I convert a column to datetime format? df[ 'date' ] = pd.to_datetime(df[ 'date' ]) ...
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The Exclusive Way to Declare Variables in Oracle Procedure

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Declare record type variables in PLSQL

There are four data types in PLSQL. Those are Numeric, Char, Boolean, and Date/Time. Each data type and its features are demonstrated. And explained how to declare variables in PLSQL procedure.

Data types

Here are the four popular data types in PLSQL.

1. Numeric


DEC, DECIMAL, and NUMERIC are used to declare fixed-point numbers with a precision of a maximum of 38 decimal digits. INTEGER, INT, and SMALLINT declare integers with a maximum precision of 38 digits.

2. Char


Char and Varchar data types support storing data of 1 t0 2000 bytes. The VARCHAR2 supports 1 to 4000 bytes of data. The VARCHAR and VARCHAR2 release the unused space in memory,

 3. Date/Time


The range for the Date is from 01-Jan-4712 BC to 31-DEC-9999. It stores the data in date format DD-MON-YYYY. The value is written in single quotes.

4. Boolean


BOOLEAN datatype stores logical values and can be either TRUE or FALSE.

Declare variables


The Declare block in PL/SQL is reserved for variable declaration. The code between begin and end blocks will participate in the execution.


PL/SQL variable-declaration


DECLARE

A NUMBER(4,1) := 11.2; B PLS_INTEGER:=78; C NUMBER(2) :=11; D CHAR(1) :='P'; E varchar (4):='GOOD'; V1 CHAR (1):='T'; D1 DATE:='01-01-2020'; -- Displays current date D2 DATE:=SYSDATE;
BEGIN

Dbms_output.put_line('A:'||' '|| A ); Dbms_output.put_line('B:'||' '|| B); Dbms_output.NEW_LINE; Dbms_output.put_line('C:'||' '|| C); Dbms_output.put_line ('D:'||' '|| D); Dbms_output.NEW_LINE; Dbms_output.put_line('D1' ||CHR(9) ||'Today's DATE '); Dbms_output.put_line(D1|| CHR(9) || D2); Dbms_output.put_line ('V1:'||' '|| V1);
END;

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