The filterFeatures methods enables users to filter features
based on a variable in their rowData. The features matching the
filter will be returned as a new object of class QFeatures. The
filters can be provided as instances of class AnnotationFilter
(see below) or as formulas.
VariableFilter(field, value, condition = "==", not = FALSE)
# S4 method for QFeatures,AnnotationFilter
filterFeatures(object, filter, na.rm = FALSE, ...)
# S4 method for QFeatures,formula
filterFeatures(object, filter, na.rm = FALSE, ...)character(1) refering to the name of the variable
to apply the filter on.
character() or integer() value for the
CharacterVariableFilter and NumericVariableFilter filters
respectively.
character(1) defining the condition to be used in
the filter. For NumericVariableFilter, one of "==",
"!=", ">", "<", ">=" or "<=". For
CharacterVariableFilter, one of "==", "!=",
"startsWith", "endsWith" or "contains". Default
condition is "==".
logical(1) indicating whether the filtering should be negated
or not. TRUE indicates is negated (!). FALSE indicates not negated.
Default not is FALSE, so no negation.
An instance of class QFeatures.
Either an instance of class AnnotationFilter or a formula.
logical(1) indicating whether missing values should
be removed. Default is FALSE.
Additional parameters. Currently ignored.
An filtered QFeature object.
The variable filters are filters as defined in the
AnnotationFilter package. In addition to the pre-defined filter,
users can arbitrarily set a field on which to operate. These
arbitrary filters operate either on a character variables (as
CharacterVariableFilter objects) or numerics (as
NumericVariableFilters objects), which can be created with the
VariableFilter constructor.
The QFeatures man page for subsetting and the QFeatures
vignette provides an extended example.
## ----------------------------------------
## Creating character and numberic
## variable filters
## ----------------------------------------
VariableFilter(field = "my_var",
value = "value_to_keep",
condition = "==")
#> class: CharacterVariableFilter
#> condition: ==
#> value: value_to_keep
VariableFilter(field = "my_num_var",
value = 0.05,
condition = "<=")
#> class: NumericVariableFilter
#> condition: <=
#> value: 0.05
example(aggregateFeatures)
#>
#> aggrgF> ## ---------------------------------------
#> aggrgF> ## An example QFeatures with PSM-level data
#> aggrgF> ## ---------------------------------------
#> aggrgF> data(feat1)
#>
#> aggrgF> feat1
#> An instance of class QFeatures containing 1 assays:
#> [1] psms: SummarizedExperiment with 10 rows and 2 columns
#>
#> aggrgF> ## Aggregate PSMs into peptides
#> aggrgF> feat1 <- aggregateFeatures(feat1, "psms", "Sequence", name = "peptides")
#>
#> aggrgF> feat1
#> An instance of class QFeatures containing 2 assays:
#> [1] psms: SummarizedExperiment with 10 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 3 rows and 2 columns
#>
#> aggrgF> ## Aggregate peptides into proteins
#> aggrgF> feat1 <- aggregateFeatures(feat1, "peptides", "Protein", name = "proteins")
#>
#> aggrgF> feat1
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 10 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 3 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 2 rows and 2 columns
#>
#> aggrgF> assay(feat1[[1]])
#> S1 S2
#> PSM1 1 11
#> PSM2 2 12
#> PSM3 3 13
#> PSM4 4 14
#> PSM5 5 15
#> PSM6 6 16
#> PSM7 7 17
#> PSM8 8 18
#> PSM9 9 19
#> PSM10 10 20
#>
#> aggrgF> assay(feat1[[2]])
#> S1 S2
#> ELGNDAYK 5.0 15.0
#> IAEESNFPFIK 8.5 18.5
#> SYGFNAAR 2.0 12.0
#>
#> aggrgF> aggcounts(feat1[[2]])
#> S1 S2
#> ELGNDAYK 3 3
#> IAEESNFPFIK 4 4
#> SYGFNAAR 3 3
#>
#> aggrgF> assay(feat1[[3]])
#> S1 S2
#> ProtA 3.5 13.5
#> ProtB 8.5 18.5
#>
#> aggrgF> aggcounts(feat1[[3]])
#> S1 S2
#> ProtA 2 2
#> ProtB 1 1
#>
#> aggrgF> ## --------------------------------------------
#> aggrgF> ## Aggregation with missing quantitative values
#> aggrgF> ## --------------------------------------------
#> aggrgF> data(ft_na)
#>
#> aggrgF> ft_na
#> An instance of class QFeatures containing 1 assays:
#> [1] na: SummarizedExperiment with 4 rows and 3 columns
#>
#> aggrgF> assay(ft_na[[1]])
#> A B C
#> a NA 5 9
#> b 2 6 10
#> c 3 NA 11
#> d NA 8 12
#>
#> aggrgF> rowData(ft_na[[1]])
#> DataFrame with 4 rows and 2 columns
#> X Y
#> <integer> <character>
#> a 1 A
#> b 2 B
#> c 1 A
#> d 2 B
#>
#> aggrgF> ## By default, missing values are propagated
#> aggrgF> ft2 <- aggregateFeatures(ft_na, 1, fcol = "X", fun = colSums)
#> Your quantitative data contain missing values. Please read the relevant
#> section(s) in the aggregateFeatures manual page regarding the effects
#> of missing values on data aggregation.
#>
#> aggrgF> assay(ft2[[2]])
#> A B C
#> 1 NA NA 20
#> 2 NA 14 22
#>
#> aggrgF> aggcounts(ft2[[2]])
#> A B C
#> 1 1 1 2
#> 2 1 2 2
#>
#> aggrgF> ## The rowData .n variable tallies number of initial rows that
#> aggrgF> ## were aggregated (irrespective of NAs) for all the samples.
#> aggrgF> rowData(ft2[[2]])
#> DataFrame with 2 rows and 3 columns
#> X Y .n
#> <integer> <character> <integer>
#> 1 1 A 2
#> 2 2 B 2
#>
#> aggrgF> ## Ignored when setting na.rm = TRUE
#> aggrgF> ft3 <- aggregateFeatures(ft_na, 1, fcol = "X", fun = colSums, na.rm = TRUE)
#> Your quantitative data contain missing values. Please read the relevant
#> section(s) in the aggregateFeatures manual page regarding the effects
#> of missing values on data aggregation.
#>
#> aggrgF> assay(ft3[[2]])
#> A B C
#> 1 3 5 20
#> 2 2 14 22
#>
#> aggrgF> aggcounts(ft3[[2]])
#> A B C
#> 1 1 1 2
#> 2 1 2 2
#>
#> aggrgF> ## -----------------------------------------------
#> aggrgF> ## Aggregation with missing values in the row data
#> aggrgF> ## -----------------------------------------------
#> aggrgF> ## Row data results without any NAs, which includes the
#> aggrgF> ## Y variables
#> aggrgF> rowData(ft2[[2]])
#> DataFrame with 2 rows and 3 columns
#> X Y .n
#> <integer> <character> <integer>
#> 1 1 A 2
#> 2 2 B 2
#>
#> aggrgF> ## Missing value in the Y feature variable
#> aggrgF> rowData(ft_na[[1]])[1, "Y"] <- NA
#>
#> aggrgF> rowData(ft_na[[1]])
#> DataFrame with 4 rows and 2 columns
#> X Y
#> <integer> <character>
#> a 1 NA
#> b 2 B
#> c 1 A
#> d 2 B
#>
#> aggrgF> ft3 <- aggregateFeatures(ft_na, 1, fcol = "X", fun = colSums)
#> Your quantitative and row data contain missing values. Please read the
#> relevant section(s) in the aggregateFeatures manual page regarding the
#> effects of missing values on data aggregation.
#>
#> aggrgF> ## The Y feature variable has been dropped!
#> aggrgF> assay(ft3[[2]])
#> A B C
#> 1 NA NA 20
#> 2 NA 14 22
#>
#> aggrgF> rowData(ft3[[2]])
#> DataFrame with 2 rows and 2 columns
#> X .n
#> <integer> <integer>
#> 1 1 2
#> 2 2 2
#>
#> aggrgF> ## --------------------------------------------
#> aggrgF> ## Using a peptide-by-proteins adjacency matrix
#> aggrgF> ## --------------------------------------------
#> aggrgF>
#> aggrgF> ## Let's use assay peptides from object feat1 and
#> aggrgF> ## define that peptide SYGFNAAR maps to proteins
#> aggrgF> ## Prot A and B
#> aggrgF>
#> aggrgF> se <- feat1[["peptides"]]
#>
#> aggrgF> rowData(se)$Protein[3] <- c("ProtA;ProtB")
#>
#> aggrgF> rowData(se)
#> DataFrame with 3 rows and 4 columns
#> Sequence Protein location .n
#> <character> <character> <character> <integer>
#> ELGNDAYK ELGNDAYK ProtA Mitochondr... 3
#> IAEESNFPFIK IAEESNFPFI... ProtB unknown 4
#> SYGFNAAR SYGFNAAR ProtA;Prot... Mitochondr... 3
#>
#> aggrgF> ## Manual encoding of the adjacency matrix
#> aggrgF> adj <- matrix(0, nrow = 3, ncol = 2,
#> aggrgF+ dimnames = list(rownames(se),
#> aggrgF+ c("ProtA", "ProtB")))
#>
#> aggrgF> adj[1, 1] <- adj[2, 2] <- adj[3, 1:2] <- 1
#>
#> aggrgF> adj
#> ProtA ProtB
#> ELGNDAYK 1 0
#> IAEESNFPFIK 0 1
#> SYGFNAAR 1 1
#>
#> aggrgF> rowData(se)$adjacencyMatrix <- adj
#>
#> aggrgF> rowData(se)
#> DataFrame with 3 rows and 5 columns
#> Sequence Protein location .n adjacencyMatrix
#> <character> <character> <character> <integer> <matrix>
#> ELGNDAYK ELGNDAYK ProtA Mitochondr... 3 1:0
#> IAEESNFPFIK IAEESNFPFI... ProtB unknown 4 0:1
#> SYGFNAAR SYGFNAAR ProtA;Prot... Mitochondr... 3 1:1
#>
#> aggrgF> adjacencyMatrix(se)
#> ProtA ProtB
#> ELGNDAYK 1 0
#> IAEESNFPFIK 0 1
#> SYGFNAAR 1 1
## ----------------------------------------------------------------
## Filter all features that are associated to the Mitochondrion in
## the location feature variable. This variable is present in all
## assays.
## ----------------------------------------------------------------
## using the forumla interface, exact mathc
filterFeatures(feat1, ~ location == "Mitochondrion")
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 6 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 2 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 1 rows and 2 columns
## using the forumula intefrace, martial match
filterFeatures(feat1, ~startsWith(location, "Mito"))
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 6 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 2 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 1 rows and 2 columns
## using a user-defined character filter
filterFeatures(feat1, VariableFilter("location", "Mitochondrion"))
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 6 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 2 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 1 rows and 2 columns
## using a user-defined character filter with partial match
filterFeatures(feat1, VariableFilter("location", "Mito", "startsWith"))
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 6 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 2 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 1 rows and 2 columns
filterFeatures(feat1, VariableFilter("location", "itochon", "contains"))
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 6 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 2 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 1 rows and 2 columns
## ----------------------------------------------------------------
## Filter all features that aren't marked as unknown (sub-cellular
## location) in the feature variable
## ----------------------------------------------------------------
## using a user-defined character filter
filterFeatures(feat1, VariableFilter("location", "unknown", condition = "!="))
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 6 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 2 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 1 rows and 2 columns
## using the forumula interface
filterFeatures(feat1, ~ location != "unknown")
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 6 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 2 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 1 rows and 2 columns
## ----------------------------------------------------------------
## Filter features that have a p-values lower or equal to 0.03
## ----------------------------------------------------------------
## using a user-defined numeric filter
filterFeatures(feat1, VariableFilter("pval", 0.03, "<="))
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 3 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 0 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 0 rows and 2 columns
## using the formula interface
filterFeatures(feat1, ~ pval <= 0.03)
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 3 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 0 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 0 rows and 2 columns
## you can also remove all p-values that are NA (if any)
filterFeatures(feat1, ~ !is.na(pval))
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 10 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 0 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 0 rows and 2 columns
## ----------------------------------------------------------------
## Negative control - filtering for an non-existing markers value
## or a missing feature variable, returning empty results
## ----------------------------------------------------------------
filterFeatures(feat1, VariableFilter("location", "not"))
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 0 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 0 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 0 rows and 2 columns
filterFeatures(feat1, ~ location == "not")
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 0 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 0 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 0 rows and 2 columns
filterFeatures(feat1, VariableFilter("foo", "bar"))
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 0 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 0 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 0 rows and 2 columns
filterFeatures(feat1, ~ foo == "bar")
#> An instance of class QFeatures containing 3 assays:
#> [1] psms: SummarizedExperiment with 0 rows and 2 columns
#> [2] peptides: SummarizedExperiment with 0 rows and 2 columns
#> [3] proteins: SummarizedExperiment with 0 rows and 2 columns
## ----------------------------------------------------------------
## Example with missing values
## ----------------------------------------------------------------
data(feat1)
rowData(feat1[[1]])[1, "location"] <- NA
rowData(feat1[[1]])
#> DataFrame with 10 rows and 5 columns
#> Sequence Protein Var location pval
#> <character> <character> <integer> <character> <numeric>
#> PSM1 SYGFNAAR ProtA 1 NA 0.084
#> PSM2 SYGFNAAR ProtA 2 Mitochondr... 0.077
#> PSM3 SYGFNAAR ProtA 3 Mitochondr... 0.063
#> PSM4 ELGNDAYK ProtA 4 Mitochondr... 0.073
#> PSM5 ELGNDAYK ProtA 5 Mitochondr... 0.012
#> PSM6 ELGNDAYK ProtA 6 Mitochondr... 0.011
#> PSM7 IAEESNFPFI... ProtB 7 unknown 0.075
#> PSM8 IAEESNFPFI... ProtB 8 unknown 0.038
#> PSM9 IAEESNFPFI... ProtB 9 unknown 0.028
#> PSM10 IAEESNFPFI... ProtB 10 unknown 0.097
## The row with the NA is not removed
rowData(filterFeatures(feat1, ~ location == "Mitochondrion")[[1]])
#> DataFrame with 6 rows and 5 columns
#> Sequence Protein Var location pval
#> <character> <character> <integer> <character> <numeric>
#> PSM1 SYGFNAAR ProtA 1 NA 0.084
#> PSM2 SYGFNAAR ProtA 2 Mitochondr... 0.077
#> PSM3 SYGFNAAR ProtA 3 Mitochondr... 0.063
#> PSM4 ELGNDAYK ProtA 4 Mitochondr... 0.073
#> PSM5 ELGNDAYK ProtA 5 Mitochondr... 0.012
#> PSM6 ELGNDAYK ProtA 6 Mitochondr... 0.011
rowData(filterFeatures(feat1, ~ location == "Mitochondrion", na.rm = FALSE)[[1]])
#> DataFrame with 6 rows and 5 columns
#> Sequence Protein Var location pval
#> <character> <character> <integer> <character> <numeric>
#> PSM1 SYGFNAAR ProtA 1 NA 0.084
#> PSM2 SYGFNAAR ProtA 2 Mitochondr... 0.077
#> PSM3 SYGFNAAR ProtA 3 Mitochondr... 0.063
#> PSM4 ELGNDAYK ProtA 4 Mitochondr... 0.073
#> PSM5 ELGNDAYK ProtA 5 Mitochondr... 0.012
#> PSM6 ELGNDAYK ProtA 6 Mitochondr... 0.011
## The row with the NA is removed
rowData(filterFeatures(feat1, ~ location == "Mitochondrion", na.rm = TRUE)[[1]])
#> DataFrame with 5 rows and 5 columns
#> Sequence Protein Var location pval
#> <character> <character> <integer> <character> <numeric>
#> PSM2 SYGFNAAR ProtA 2 Mitochondr... 0.077
#> PSM3 SYGFNAAR ProtA 3 Mitochondr... 0.063
#> PSM4 ELGNDAYK ProtA 4 Mitochondr... 0.073
#> PSM5 ELGNDAYK ProtA 5 Mitochondr... 0.012
#> PSM6 ELGNDAYK ProtA 6 Mitochondr... 0.011
## Note that in situations with missing values, it is possible to
## use the `%in%` operator or filter missing values out
## explicitly.
rowData(filterFeatures(feat1, ~ location %in% "Mitochondrion")[[1]])
#> DataFrame with 5 rows and 5 columns
#> Sequence Protein Var location pval
#> <character> <character> <integer> <character> <numeric>
#> PSM2 SYGFNAAR ProtA 2 Mitochondr... 0.077
#> PSM3 SYGFNAAR ProtA 3 Mitochondr... 0.063
#> PSM4 ELGNDAYK ProtA 4 Mitochondr... 0.073
#> PSM5 ELGNDAYK ProtA 5 Mitochondr... 0.012
#> PSM6 ELGNDAYK ProtA 6 Mitochondr... 0.011
rowData(filterFeatures(feat1, ~ location %in% c(NA, "Mitochondrion"))[[1]])
#> DataFrame with 6 rows and 5 columns
#> Sequence Protein Var location pval
#> <character> <character> <integer> <character> <numeric>
#> PSM1 SYGFNAAR ProtA 1 NA 0.084
#> PSM2 SYGFNAAR ProtA 2 Mitochondr... 0.077
#> PSM3 SYGFNAAR ProtA 3 Mitochondr... 0.063
#> PSM4 ELGNDAYK ProtA 4 Mitochondr... 0.073
#> PSM5 ELGNDAYK ProtA 5 Mitochondr... 0.012
#> PSM6 ELGNDAYK ProtA 6 Mitochondr... 0.011
## Explicit handling
filterFeatures(feat1, ~ !is.na(location) & location == "Mitochondrion")
#> An instance of class QFeatures containing 1 assays:
#> [1] psms: SummarizedExperiment with 5 rows and 2 columns
## Using the pipe operator
library("magrittr")
feat1 %>%
filterFeatures( ~ !is.na(location)) %>%
filterFeatures( ~ location == "Mitochondrion")
#> An instance of class QFeatures containing 1 assays:
#> [1] psms: SummarizedExperiment with 5 rows and 2 columns