Overview

Dataset statistics

Number of variables5
Number of observations36
Missing cells0
Missing cells (%)0.0%
Duplicate rows0
Duplicate rows (%)0.0%
Total size in memory1.6 KiB
Average record size in memory45.7 B

Variable types

Numeric2
Text3

Dataset

Description국토의 계획 및 이용에 관한 연차보고서를 각 연도, 제목, 파일명 및 다운로드 URL로 구성하여 연도별 데이터로 제공합니다.
Author국토교통부
URLhttps://www.data.go.kr/data/15122709/fileData.do

Alerts

순번 is highly overall correlated with 연도High correlation
연도 is highly overall correlated with 순번High correlation
순번 has unique valuesUnique
연도 has unique valuesUnique
자료명 has unique valuesUnique
자료경로 has unique valuesUnique
자료파일명 has unique valuesUnique

Reproduction

Analysis started2023-12-12 10:20:50.675593
Analysis finished2023-12-12 10:20:51.413893
Duration0.74 seconds
Software versionydata-profiling vv4.5.1
Download configurationconfig.json

Variables

순번
Real number (ℝ)

HIGH CORRELATION  UNIQUE 

Distinct36
Distinct (%)100.0%
Missing0
Missing (%)0.0%
Infinite0
Infinite (%)0.0%
Mean18.5
Minimum1
Maximum36
Zeros0
Zeros (%)0.0%
Negative0
Negative (%)0.0%
Memory size456.0 B
2023-12-12T19:20:51.488945image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/

Quantile statistics

Minimum1
5-th percentile2.75
Q19.75
median18.5
Q327.25
95-th percentile34.25
Maximum36
Range35
Interquartile range (IQR)17.5

Descriptive statistics

Standard deviation10.535654
Coefficient of variation (CV)0.5694948
Kurtosis-1.2
Mean18.5
Median Absolute Deviation (MAD)9
Skewness0
Sum666
Variance111
MonotonicityStrictly increasing
2023-12-12T19:20:51.620945image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/
Histogram with fixed size bins (bins=36)
ValueCountFrequency (%)
1 1
 
2.8%
20 1
 
2.8%
22 1
 
2.8%
23 1
 
2.8%
24 1
 
2.8%
25 1
 
2.8%
26 1
 
2.8%
27 1
 
2.8%
28 1
 
2.8%
29 1
 
2.8%
Other values (26) 26
72.2%
ValueCountFrequency (%)
1 1
2.8%
2 1
2.8%
3 1
2.8%
4 1
2.8%
5 1
2.8%
6 1
2.8%
7 1
2.8%
8 1
2.8%
9 1
2.8%
10 1
2.8%
ValueCountFrequency (%)
36 1
2.8%
35 1
2.8%
34 1
2.8%
33 1
2.8%
32 1
2.8%
31 1
2.8%
30 1
2.8%
29 1
2.8%
28 1
2.8%
27 1
2.8%

연도
Real number (ℝ)

HIGH CORRELATION  UNIQUE 

Distinct36
Distinct (%)100.0%
Missing0
Missing (%)0.0%
Infinite0
Infinite (%)0.0%
Mean2003.9167
Minimum1985
Maximum2022
Zeros0
Zeros (%)0.0%
Negative0
Negative (%)0.0%
Memory size456.0 B
2023-12-12T19:20:51.762752image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/

Quantile statistics

Minimum1985
5-th percentile1987.5
Q11994.75
median2003.5
Q32013.25
95-th percentile2020.25
Maximum2022
Range37
Interquartile range (IQR)18.5

Descriptive statistics

Standard deviation11.069585
Coefficient of variation (CV)0.0055239748
Kurtosis-1.2174017
Mean2003.9167
Median Absolute Deviation (MAD)9.5
Skewness-0.019510399
Sum72141
Variance122.53571
MonotonicityStrictly increasing
2023-12-12T19:20:51.888342image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/
Histogram with fixed size bins (bins=36)
ValueCountFrequency (%)
1985 1
 
2.8%
2006 1
 
2.8%
2008 1
 
2.8%
2009 1
 
2.8%
2010 1
 
2.8%
2011 1
 
2.8%
2012 1
 
2.8%
2013 1
 
2.8%
2014 1
 
2.8%
2015 1
 
2.8%
Other values (26) 26
72.2%
ValueCountFrequency (%)
1985 1
2.8%
1986 1
2.8%
1988 1
2.8%
1989 1
2.8%
1990 1
2.8%
1991 1
2.8%
1992 1
2.8%
1993 1
2.8%
1994 1
2.8%
1995 1
2.8%
ValueCountFrequency (%)
2022 1
2.8%
2021 1
2.8%
2020 1
2.8%
2019 1
2.8%
2018 1
2.8%
2017 1
2.8%
2016 1
2.8%
2015 1
2.8%
2014 1
2.8%
2013 1
2.8%

자료명
Text

UNIQUE 

Distinct36
Distinct (%)100.0%
Missing0
Missing (%)0.0%
Memory size420.0 B
2023-12-12T19:20:52.165000image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/

Length

Max length34
Median length27
Mean length27.194444
Min length27

Characters and Unicode

Total characters979
Distinct characters29
Distinct categories4 ?
Distinct scripts2 ?
Distinct blocks2 ?
The Unicode Standard assigns character properties to each code point, which can be used to analyse textual variables.

Unique

Unique36 ?
Unique (%)100.0%

Sample

1st row1985년 국토의 계획 및 이용에 관한 연차보고서
2nd row1986년 국토의 계획 및 이용에 관한 연차보고서
3rd row1988년 국토의 계획 및 이용에 관한 연차보고서
4th row1989년 국토의 계획 및 이용에 관한 연차보고서
5th row1990년 국토의 계획 및 이용에 관한 연차보고서
ValueCountFrequency (%)
계획 36
14.2%
및 36
14.2%
이용에 36
14.2%
관한 36
14.2%
연차보고서 36
14.2%
국토의 36
14.2%
1985년 1
 
0.4%
2012년 1
 
0.4%
2006년 1
 
0.4%
2013년 1
 
0.4%
Other values (34) 34
13.4%
2023-12-12T19:20:52.590328image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/

Most occurring characters

ValueCountFrequency (%)
218
22.3%
0 37
 
3.8%
에 36
 
3.7%
및 36
 
3.7%
차 36
 
3.7%
연 36
 
3.7%
한 36
 
3.7%
관 36
 
3.7%
서 36
 
3.7%
용 36
 
3.7%
Other values (19) 436
44.5%

Most occurring categories

ValueCountFrequency (%)
Other Letter 612
62.5%
Space Separator 218
 
22.3%
Decimal Number 148
 
15.1%
Math Symbol 1
 
0.1%

Most frequent character per category

Other Letter
ValueCountFrequency (%)
에 36
 
5.9%
및 36
 
5.9%
차 36
 
5.9%
연 36
 
5.9%
한 36
 
5.9%
관 36
 
5.9%
서 36
 
5.9%
용 36
 
5.9%
이 36
 
5.9%
획 36
 
5.9%
Other values (7) 252
41.2%
Decimal Number
ValueCountFrequency (%)
0 37
25.0%
2 30
20.3%
1 28
18.9%
9 28
18.9%
8 8
 
5.4%
6 4
 
2.7%
5 4
 
2.7%
4 3
 
2.0%
3 3
 
2.0%
7 3
 
2.0%
Space Separator
ValueCountFrequency (%)
218
100.0%
Math Symbol
ValueCountFrequency (%)
~ 1
100.0%

Most occurring scripts

ValueCountFrequency (%)
Hangul 612
62.5%
Common 367
37.5%

Most frequent character per script

Hangul
ValueCountFrequency (%)
에 36
 
5.9%
및 36
 
5.9%
차 36
 
5.9%
연 36
 
5.9%
한 36
 
5.9%
관 36
 
5.9%
서 36
 
5.9%
용 36
 
5.9%
이 36
 
5.9%
획 36
 
5.9%
Other values (7) 252
41.2%
Common
ValueCountFrequency (%)
218
59.4%
0 37
 
10.1%
2 30
 
8.2%
1 28
 
7.6%
9 28
 
7.6%
8 8
 
2.2%
6 4
 
1.1%
5 4
 
1.1%
4 3
 
0.8%
3 3
 
0.8%
Other values (2) 4
 
1.1%

Most occurring blocks

ValueCountFrequency (%)
Hangul 612
62.5%
ASCII 367
37.5%

Most frequent character per block

ASCII
ValueCountFrequency (%)
218
59.4%
0 37
 
10.1%
2 30
 
8.2%
1 28
 
7.6%
9 28
 
7.6%
8 8
 
2.2%
6 4
 
1.1%
5 4
 
1.1%
4 3
 
0.8%
3 3
 
0.8%
Other values (2) 4
 
1.1%
Hangul
ValueCountFrequency (%)
에 36
 
5.9%
및 36
 
5.9%
차 36
 
5.9%
연 36
 
5.9%
한 36
 
5.9%
관 36
 
5.9%
서 36
 
5.9%
용 36
 
5.9%
이 36
 
5.9%
획 36
 
5.9%
Other values (7) 252
41.2%

자료경로
Text

UNIQUE 

Distinct36
Distinct (%)100.0%
Missing0
Missing (%)0.0%
Memory size420.0 B
2023-12-12T19:20:52.928403image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/

Length

Max length106
Median length101
Mean length101.13889
Min length101

Characters and Unicode

Total characters3641
Distinct characters42
Distinct categories6 ?
Distinct scripts2 ?
Distinct blocks1 ?
The Unicode Standard assigns character properties to each code point, which can be used to analyse textual variables.

Unique

Unique36 ?
Unique (%)100.0%

Sample

1st rowhttps://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1985.pdf
2nd rowhttps://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1986.pdf
3rd rowhttps://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1988.pdf
4th rowhttps://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1989.pdf
5th rowhttps://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1990.pdf
ValueCountFrequency (%)
https://www.eum.go.kr/web/filedownload.do?file=/20201021/sysmanage/upis/upyearreportform.jsp/1985.pdf 1
 
2.8%
https://www.eum.go.kr/web/filedownload.do?file=/20201021/sysmanage/upis/upyearreportform.jsp/1986.pdf 1
 
2.8%
https://www.eum.go.kr/web/filedownload.do?file=/20201021/sysmanage/upis/upyearreportform.jsp/2013.pdf 1
 
2.8%
https://www.eum.go.kr/web/filedownload.do?file=/20201021/sysmanage/upis/upyearreportform.jsp/2007.pdf 1
 
2.8%
https://www.eum.go.kr/web/filedownload.do?file=/20201021/sysmanage/upis/upyearreportform.jsp/2008.pdf 1
 
2.8%
https://www.eum.go.kr/web/filedownload.do?file=/20201021/sysmanage/upis/upyearreportform.jsp/2009.pdf 1
 
2.8%
https://www.eum.go.kr/web/filedownload.do?file=/20201021/sysmanage/upis/upyearreportform.jsp/2010.pdf 1
 
2.8%
https://www.eum.go.kr/web/filedownload.do?file=/20201021/sysmanage/upis/upyearreportform.jsp/2011.pdf 1
 
2.8%
https://www.eum.go.kr/web/filedownload.do?file=/20201021/sysmanage/upis/upyearreportform.jsp/2012.pdf 1
 
2.8%
https://www.eum.go.kr/web/filedownload.do?file=/20201021/sysmanage/upis/upyearreportform.jsp/2014.pdf 1
 
2.8%
Other values (26) 26
72.2%
2023-12-12T19:20:53.411170image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/

Most occurring characters

ValueCountFrequency (%)
/ 324
 
8.9%
e 252
 
6.9%
o 216
 
5.9%
p 216
 
5.9%
. 216
 
5.9%
s 180
 
4.9%
w 180
 
4.9%
a 144
 
4.0%
r 144
 
4.0%
0 140
 
3.8%
Other values (32) 1629
44.7%

Most occurring categories

ValueCountFrequency (%)
Lowercase Letter 2340
64.3%
Other Punctuation 612
 
16.8%
Decimal Number 436
 
12.0%
Uppercase Letter 216
 
5.9%
Math Symbol 36
 
1.0%
Connector Punctuation 1
 
< 0.1%

Most frequent character per category

Lowercase Letter
ValueCountFrequency (%)
e 252
 
10.8%
o 216
 
9.2%
p 216
 
9.2%
s 180
 
7.7%
w 180
 
7.7%
a 144
 
6.2%
r 144
 
6.2%
m 108
 
4.6%
i 108
 
4.6%
l 108
 
4.6%
Other values (11) 684
29.2%
Decimal Number
ValueCountFrequency (%)
0 140
32.1%
2 135
31.0%
1 103
23.6%
9 28
 
6.4%
8 8
 
1.8%
5 5
 
1.1%
6 5
 
1.1%
7 5
 
1.1%
3 4
 
0.9%
4 3
 
0.7%
Uppercase Letter
ValueCountFrequency (%)
F 72
33.3%
Y 36
16.7%
U 36
16.7%
R 36
16.7%
D 36
16.7%
Other Punctuation
ValueCountFrequency (%)
/ 324
52.9%
. 216
35.3%
? 36
 
5.9%
: 36
 
5.9%
Math Symbol
ValueCountFrequency (%)
= 36
100.0%
Connector Punctuation
ValueCountFrequency (%)
_ 1
100.0%

Most occurring scripts

ValueCountFrequency (%)
Latin 2556
70.2%
Common 1085
29.8%

Most frequent character per script

Latin
ValueCountFrequency (%)
e 252
 
9.9%
o 216
 
8.5%
p 216
 
8.5%
s 180
 
7.0%
w 180
 
7.0%
a 144
 
5.6%
r 144
 
5.6%
m 108
 
4.2%
i 108
 
4.2%
l 108
 
4.2%
Other values (16) 900
35.2%
Common
ValueCountFrequency (%)
/ 324
29.9%
. 216
19.9%
0 140
12.9%
2 135
12.4%
1 103
 
9.5%
= 36
 
3.3%
? 36
 
3.3%
: 36
 
3.3%
9 28
 
2.6%
8 8
 
0.7%
Other values (6) 23
 
2.1%

Most occurring blocks

ValueCountFrequency (%)
ASCII 3641
100.0%

Most frequent character per block

ASCII
ValueCountFrequency (%)
/ 324
 
8.9%
e 252
 
6.9%
o 216
 
5.9%
p 216
 
5.9%
. 216
 
5.9%
s 180
 
4.9%
w 180
 
4.9%
a 144
 
4.0%
r 144
 
4.0%
0 140
 
3.8%
Other values (32) 1629
44.7%

자료파일명
Text

UNIQUE 

Distinct36
Distinct (%)100.0%
Missing0
Missing (%)0.0%
Memory size420.0 B
2023-12-12T19:20:53.654895image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/

Length

Max length13
Median length8
Mean length8.1388889
Min length8

Characters and Unicode

Total characters293
Distinct characters15
Distinct categories4 ?
Distinct scripts2 ?
Distinct blocks1 ?
The Unicode Standard assigns character properties to each code point, which can be used to analyse textual variables.

Unique

Unique36 ?
Unique (%)100.0%

Sample

1st row1985.pdf
2nd row1986.pdf
3rd row1988.pdf
4th row1989.pdf
5th row1990.pdf
ValueCountFrequency (%)
1985.pdf 1
 
2.8%
1986.pdf 1
 
2.8%
2013.pdf 1
 
2.8%
2007.pdf 1
 
2.8%
2008.pdf 1
 
2.8%
2009.pdf 1
 
2.8%
2010.pdf 1
 
2.8%
2011.pdf 1
 
2.8%
2012.pdf 1
 
2.8%
2014.pdf 1
 
2.8%
Other values (26) 26
72.2%
2023-12-12T19:20:54.020743image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/

Most occurring characters

ValueCountFrequency (%)
0 37
12.6%
. 36
12.3%
p 36
12.3%
d 36
12.3%
f 36
12.3%
2 30
10.2%
1 28
9.6%
9 28
9.6%
8 8
 
2.7%
5 4
 
1.4%
Other values (5) 14
 
4.8%

Most occurring categories

ValueCountFrequency (%)
Decimal Number 148
50.5%
Lowercase Letter 108
36.9%
Other Punctuation 36
 
12.3%
Connector Punctuation 1
 
0.3%

Most frequent character per category

Decimal Number
ValueCountFrequency (%)
0 37
25.0%
2 30
20.3%
1 28
18.9%
9 28
18.9%
8 8
 
5.4%
5 4
 
2.7%
6 4
 
2.7%
4 3
 
2.0%
3 3
 
2.0%
7 3
 
2.0%
Lowercase Letter
ValueCountFrequency (%)
p 36
33.3%
d 36
33.3%
f 36
33.3%
Other Punctuation
ValueCountFrequency (%)
. 36
100.0%
Connector Punctuation
ValueCountFrequency (%)
_ 1
100.0%

Most occurring scripts

ValueCountFrequency (%)
Common 185
63.1%
Latin 108
36.9%

Most frequent character per script

Common
ValueCountFrequency (%)
0 37
20.0%
. 36
19.5%
2 30
16.2%
1 28
15.1%
9 28
15.1%
8 8
 
4.3%
5 4
 
2.2%
6 4
 
2.2%
4 3
 
1.6%
3 3
 
1.6%
Other values (2) 4
 
2.2%
Latin
ValueCountFrequency (%)
p 36
33.3%
d 36
33.3%
f 36
33.3%

Most occurring blocks

ValueCountFrequency (%)
ASCII 293
100.0%

Most frequent character per block

ASCII
ValueCountFrequency (%)
0 37
12.6%
. 36
12.3%
p 36
12.3%
d 36
12.3%
f 36
12.3%
2 30
10.2%
1 28
9.6%
9 28
9.6%
8 8
 
2.7%
5 4
 
1.4%
Other values (5) 14
 
4.8%

Interactions

2023-12-12T19:20:51.079964image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/
2023-12-12T19:20:50.890726image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/
2023-12-12T19:20:51.166024image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/
2023-12-12T19:20:50.979123image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/

Correlations

2023-12-12T19:20:54.121865image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/
순번연도자료명자료경로자료파일명
순번1.0000.9981.0001.0001.000
연도0.9981.0001.0001.0001.000
자료명1.0001.0001.0001.0001.000
자료경로1.0001.0001.0001.0001.000
자료파일명1.0001.0001.0001.0001.000
2023-12-12T19:20:54.216139image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/
순번연도
순번1.0001.000
연도1.0001.000

Missing values

2023-12-12T19:20:51.275150image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/
A simple visualization of nullity by column.
2023-12-12T19:20:51.374609image/svg+xmlMatplotlib v3.7.2, https://matplotlib.org/
Nullity matrix is a data-dense display which lets you quickly visually pick out patterns in data completion.

Sample

순번연도자료명자료경로자료파일명
0119851985년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1985.pdf1985.pdf
1219861986년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1986.pdf1986.pdf
2319881988년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1988.pdf1988.pdf
3419891989년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1989.pdf1989.pdf
4519901990년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1990.pdf1990.pdf
5619911991년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1991.pdf1991.pdf
6719921992년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1992.pdf1992.pdf
7819931993년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1993.pdf1993.pdf
8919941994년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1994.pdf1994.pdf
91019951995년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/1995.pdf1995.pdf
순번연도자료명자료경로자료파일명
262720132013년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/2013.pdf2013.pdf
272820142014년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/2014.pdf2014.pdf
282920152015년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/2015.pdf2015.pdf
293020162016년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/2016.pdf2016.pdf
303120172017년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20210106/sysmanage/upis/UpYearReportForm.jsp/2017.pdf2017.pdf
313220182018년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/2018.pdf2018.pdf
323320192019년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20201021/sysmanage/upis/UpYearReportForm.jsp/2019.pdf2019.pdf
333420202020년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20211117/sysmanage/upis/UpYearReportForm.jsp/2020.pdf2020.pdf
343520212021년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20211117/sysmanage/upis/UpYearReportForm.jsp/2021.pdf2021.pdf
353620222022년 국토의 계획 및 이용에 관한 연차보고서https://www.eum.go.kr/web/FileDownload.do?file=/20230215/sysmanage/upis/UpYearReportForm.jsp/2022.pdf2022.pdf