RBSE SS Informatics Practices flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Pandas Series

A one-dimensional labelled array in Pandas that stores a single data type; created with pd.Series(data, index=...), where data may be a list, tuple, dictionary, scalar or NumPy array.

DataFrame

A two-dimensional labelled table in Pandas with rows and columns, created by pd.DataFrame() from a dictionary of lists, a list of dictionaries, a 2D NumPy array or a CSV file.

loc vs iloc

df.loc selects rows and columns by label and includes the endpoint in slices; df.iloc selects by integer position and excludes the stop position, like ordinary Python slicing.

iterrows() method

A DataFrame method that yields each row as a pair (index, Series), letting a loop read row values by column label; it is slower than vectorised operations on large tables.

Boolean masking in Series

Filtering a Series with a condition such as s[s > 50]: the condition produces True or False for each element, and only elements whose position is True are returned.

read_csv()

A Pandas function that loads a delimited text file into a DataFrame; common arguments are sep, header, names, index_col, usecols, nrows, na_values and dtype.

to_csv() index parameter

In df.to_csv('f.csv') the index parameter defaults to True, so row labels are written as an extra unnamed first column; set index=False to export only the data columns.

dropna()

A DataFrame method that removes rows or columns containing missing values; axis chooses rows (0) or columns (1), while how='any'/'all' and subset limit which nulls count.

merge()

A Pandas function joining two DataFrames on common key columns, where how = inner, left, right or outer decides which unmatched rows are retained in the result.

describe()

A DataFrame method returning count, mean, std, min, quartiles and max for numeric columns; include='all' adds object columns, and NaN values are ignored while computing.

plt.plot()

A matplotlib pyplot function drawing a line chart from x and y sequences, used to show trends over time or ordered categories; style arguments include color, marker and linestyle.

plt.hist()

A pyplot function drawing a histogram, which groups numerical data into bins and plots the frequency of each bin, revealing the distribution shape of a single variable.

plt.scatter()

A pyplot function that plots one dot per observation at coordinates (x, y), used to see the relationship or correlation between two numerical variables.

plt.legend()

A pyplot function displaying a key that maps each plotted line or bar to its label; the labels must be passed with label='...' when the plot is actually drawn.

savefig()

A pyplot function that writes the current figure to an image file such as PNG or PDF; it must be called before plt.show(), which clears the figure.

DDL vs DML

DDL statements (CREATE, ALTER, DROP, TRUNCATE) define or change table structure and auto-commit; DML statements (INSERT, UPDATE, DELETE) change the rows stored inside tables.

HAVING clause

A SQL clause that filters groups after GROUP BY and aggregation, so a condition on an aggregate result such as COUNT(*) > 2 must use HAVING rather than WHERE.

GROUP BY

A SQL clause that collects rows with equal values in the listed columns into one group, so each aggregate in the SELECT list is computed once per group.

INNER JOIN

A join returning only rows whose key values match in both tables; unmatched rows from either side are dropped, unlike LEFT JOIN, which keeps all left-table rows.

SQL aggregate functions

Functions such as COUNT, SUM, AVG, MIN and MAX that collapse many rows into one value; all of them ignore NULL except COUNT(*), which counts every row.

LAN

Local Area Network: a network covering a small area such as a room, building or campus, usually privately owned, with high data rates and low error rates.

Star topology

A topology in which every node connects to a central hub or switch; one cable failure affects only one node, but failure of the central device stops the whole network.

Router

A network device operating at the network layer that forwards packets between different networks using IP addresses, choosing the best path through its routing table.

TCP vs UDP

TCP is connection-oriented and guarantees ordered, error-checked delivery with retransmission; UDP is connectionless, gives no delivery guarantee and is faster, suiting streaming and DNS queries.

HTTP

HyperText Transfer Protocol: an application-layer request-response protocol used by browsers to fetch web pages, by default on TCP port 80; HTTPS adds encryption on port 443.

Digital footprint

The trail of data a person leaves online: active footprints come from deliberate posts and comments, while passive footprints are collected silently, such as browsing history and location data.

Open source software

Software whose source code is available for anyone to study, modify and redistribute, usually under licences such as GPL, MIT or Apache; it need not be free of charge.

Software piracy

Unauthorized copying, distribution or use of licensed software; forms include softlifting, hard-disk loading, renting, counterfeiting and downloading from unlicensed online sources.

E-waste

Discarded electrical and electronic equipment such as old computers, phones and batteries; it contains toxic metals like lead, mercury and cadmium and must go to authorized recyclers.

Project report structure

A typical report contains a title page, certificate, acknowledgement, table of contents, introduction, objectives, methodology, code and output, findings, conclusion and bibliography.

groupby() in Pandas

A DataFrame method that splits rows into groups sharing a column value, applies an aggregation such as mean or sum, and combines the per-group results into a new object.

DESC table

A MySQL command that displays a table's structure: column names, data types, nullability, key constraints and defaults; used to verify a CREATE TABLE statement in the practical exam.