Pivotering av data

Datamanipulering i Julia

Katerina Zahradova

Instructor

Pivottabeller

Metod för att sammanfatta data
Omorganisering av kolumner och rader för bättre läsbarhet

Pivottabell med unstack()

unstack-struktur

unstack() för pivotering

# Using unstack to pivot
# unstack(DataFrame, :col_as_rows, :col_as_cols, :values, combine = f_to_aggregate)

unstack(penguins, :species, :sex, :body_mass_g, combine = median)

3×3 DataFrame
Row  species   MALE     FEMALE
     String15  Float64  Float64
_____________________________________
1    Adelie    4000.0   3400.0
2    Chinstrap 3950.0   3550.0
3    Gentoo    5500.0   4700.0

Pivotering med flera kolumner som rader

# Pivot on more columns as rows 
unstack(penguins, [:species, :island], :sex, :body_mass_g, combine = median)

5×4 DataFrame
Row  species    island     MALE       FEMALE
     String15   String15   Float64?   Float64?
_____________________________________________________
1    Adelie     Torgersen  4000.0    3400.0
2    Adelie     Biscoe     4000.0    3375.0
3    Adelie     Dream      3987.5    3400.0
4    Chinstrap  Dream      3950.0    3550.0
5    Gentoo     Biscoe     5500.0    4700.0

Pivotering med flera kolumner som kolumner

# Using multiple columns as columns
unstack(penguins, :sex, [:species, :island], :body_mass_g, combine = sum)

MethodError: no method matching 
unstack(::DataFrame, ::Symbol, ::Vector{Symbol}, ::Symbol; combine = sum)

Saknade värden

# Missing values for certain combinations
unstack(penguins_missing, :species, :sex, :body_mass_g, combine = median)

3×3 DataFrame
Row  species   MALE     FEMALE
     String15  Float64  Float64?
_____________________________________
1    Adelie    4000.0   3400.0
2    Chinstrap 3950.0   3550.0
3    Gentoo    5500.0   missing

Ersätta saknade värden

# Missing values for certain combinations
unstack(penguins_missing, :species, :sex, :body_mass_g, combine = median, fill = -1)

3×3 DataFrame
Row  species   MALE     FEMALE
     String15  Float64  Float64
_____________________________________
1    Adelie    4000.0    3400.0
2    Chinstrap 3950.0    3550.0
3    Gentoo    5500.0    -1

Pivottabeller är DataFrames

# Saving the pivot table
pivot_penguins = unstack(penguins_missing, :species, :sex, :body_mass_g, combine = median)

# Select only female penguins
select(pivot_penguins, :species, :FEMALE)

3×2 DataFrame
Row  species    FEMALE
     String15   Float64?
_______________________________
1    Adelie      3400.0
...

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Datamanipulering i Julia