Adding assignments solutions for course "pogRomcy Danych" about data

science and R.

pogromcy-danych/assignments/1_4.R

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+wynik <- sqrt((2+517)*1.23)

pogromcy-danych/assignments/1_5.R

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+# Text file:
+auta2012 <- read.table(file="http://biecek.pl/MOOC/dane/auta2012mini.csv",
+                       sep=";", dec=",", header=TRUE)
+
+# Excela file:
+library(gdata)
+auta2012 <- read.xls("http://biecek.pl/MOOC/dane/auta2012mini.xls", sheet=1)
+
+# RDA file (it loads whole workspace, with variables):
+load(url("http://biecek.pl/MOOC/dane/auta2012mini.rda"))

pogromcy-danych/assignments/1_6.R

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+# Text file:
+write.table(koty_ptaki, file="dane_o_kotach.csv", sep=",", dec=".")
+
+# Excela file:
+library(xlsx)
+write.xls(koty_ptaki, file="koty_ptaki.xlsx", sheetName="New Sheet")
+
+# RDA file:
+save(koty_ptaki, file="koty_ptaki.rda")
+load("koty_ptaki.rda")

pogromcy-danych/assignments/1_7.1.R

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+# 10 following letters:
+c('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j')
+letters[1:10]
+
+# Odd numbers starting from 3:
+seq(3, 21, 2)
+
+# Selected numbers from LETTERS:
+LETTERS[c(5, 10, 15, 20, 25)]
+
+# Reversed LETTERS:
+LETTERS[26:1]

pogromcy-danych/assignments/1_7.2.R

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+# All besides falcons:
+koty_ptaki[-(11:12), ]
+koty_ptaki[c(1:10, 13), ]
+
+# Only cats:
+koty_ptaki[1:7, ]
+koty_ptaki[koty_ptaki$druzyna == "Kot", ]
+
+# Only two columns:
+koty_ptaki[, c("waga", "predkosc")]
+koty_ptaki[, c(2, 4)]
+
+# All besides last column:
+koty_ptaki[, 1:6]
+koty_ptaki[, -7]
+
+# Lightweight animals:
+koty_ptaki[koty_ptaki$waga < 100, 1:4]